Developing with Nature guidance

Careful selection of plant species to support wildlife is one of the simplest changes that can be made for biodiversity.  Gardens and landscaped areas are provided in many developments, and planters can be provided in hard landscaped spaces.  Climbing plants can grow up shrubs and trees, or use walls and structures for support, providing additional niches for wildlife by allowing plants and animals to utilise vertical space.

There does not have to be a trade-off between attractive, functioning gardens and landscaped grounds, and benefitting biodiversity.  We have a huge variety of native species that are often long flowering.  With careful species selection not only does this create attractive spaces, but these species often require less maintenance and have a higher level of survival than non-natives.

Benefits to Nature

The plants in themselves will enhance biodiversity, but the biggest group of species to benefit will be the pollinators (that the plants are themselves dependent upon).  Plants can support a diverse group of insects, including their larval stage (when they feed on the plant’s roots or leaves), as well as several mammal and bird species that predate on them.  Native plants usually support the most species, and the larger the variety of plant species the more pollinator species are likely to benefit from the range of different shaped and sized flowers. 

Most plants from bulbs are early flowering and can be an important resource for early season pollinators, particularly those that have come out of hibernation.  Spring flowering trees and shrubs are vital nectar and pollen sources for pollinators in early spring, and late flowering species and those providing edible seeds and berries are crucial at the end of the year.

Ensuring habitat connectivity can be of particular benefit to pollinators and their predators as fragmentation is a leading cause of decline, which is accentuated by climate change.  Areas identified for planting should consider how wildlife can use them to move across and beyond the site.

Other benefits of pollinator planting can include providing shade and cooling, water control, carbon storage, crop pollination and pest control, and recreational use and well-being.

Key Requirements

Any scale of development can incorporate planting for pollinators, from the use of small planters and containers, pocket and large gardens, to extensive landscaped grounds.  Plants should be selected that are suited to the location and the site’s soil and environmental conditions, and intended use of the area. 

Selected species should not be potentially invasive native species, particularly when planted near to vulnerable habitats, or invasive non-native species (see Annex B).  A diverse species choice should consider the time of year and for how long the plants are flowering (to provide for pollinators throughout the year), the opportunities they provide for shelter (especially all year round shelter), the seed, fruit, pollen and nectar source they provide, and encourage diversity.

Bulbs can be planted and provide a resource in areas where other plants and trees cast too much shade later in the year.  Areas of amenity grassland can be planted with early flowering bulbs that can be cut once the leaves arising from the bulbs have died back.  Bulbs can also be planted into some meadow areas where they will not out-compete the meadow species or become invasive.

Future Management

Plants after planting may require some fertilisation and watering until they are established.  Future management will depend on the species planted, with some needing no or little on-going effort while others require regular cutting back, pruning, watering, mulching and protecting to maintain them in good condition.  Plants should be monitored to ensure they have established and are in good health, and management adapted to their needs.  Dead or dying plants should be removed and disposed of appropriately.  Plants should be replaced and if a species is found to struggle a more suitable species should be considered.  Replacements should be planted as soon as the planting season allows, so as not to degrade the biodiversity provision afforded.

Management should not be onerous for small areas, but for more extensive areas a simple planting and management plan may be appropriate to ensure the necessary management is undertaken in the future.  The plan should include instructions on how its content will be conveyed to site factors and operators, both now and in the future.

Complementary Measures 

Plants for pollinators can be incorporated into living roofs, walls and screens (measures 5 and 6), wildlife walls (measure 12), rain gardens (measure 19), and the setting of biodiverse SuDS ponds (measure 21).

Nature Notes

Different pollinators have a variety of distinct body forms that enable them to access specific flower shapes.  Many pollinators (especially bees) need both pollen and nectar, requiring a variety of plants, and not all flowers provide similar resources.  Some will have less nectar and pollen, while other flowers that have been bred for aesthetic characteristics (for example extra petals), can block access to pollen and nectar.  These should be avoided, along with species that could have negative effects if they were to seed or sucker into surrounding habitats.

Further Information

• On making development pollinator friendly see NatureScot’s Guidance – pollinators in planning and construction guide
• On selecting plant species that are not invasive see the Non-native Species Secretariat (NNSS) guidance on Gardening without harmful invasive plants
• On the selection of plants see the Royal Horticultural Society’s Find a plant database (to produce a filtered list of native wildlife and pollinator friendly species) and the RHS plants for pollinators guide
• On plants for wildlife see the RSPB’s All about the plants guide and the North East Scotland Biodiversity Partnership’s Wildlife gardening
• On plants for bees see the Bumblebee Conservation Trust’s Gardening for bumblebees, and The Wildlife Trusts’ How to attract bumblebees to your garden and The best plants for bees and pollinators
• On plants for butterflies see Butterfly Conservation’s guides for Caterpillar food plants and Nectar plants for butterflies, and the Wildlife Trusts’ How to attract butterflies to your garden
• On plants for moths see the Wildlife Trusts’ How to attract moths and bats to your garden and the RSPB’s Grow food for moths

A wildflower meadow consists of a variety of wild grasses and wildflowers growing generally on unimproved and ungrazed land in conditions suitable for less vigorous and more easily outcompeted species.  Meadows can be large, enhancing the biodiversity value of a public greenspace, or small, occupying a small corner of a garden or established as part of another measure (such as a bee bank or buffer strip to a swale).  They include a range of different forms:

• Short flowering lawn – in place of the common monoculture grass lawn using seed mixes or wildflower turves favouring low growing and ground hugging species, which require less cutting than amenity grass.
• Wet meadow – in areas with damp or wet conditions that may periodically flood, meadow species can thrive so long as water flows do not improve the nutrient poor conditions.
• Hedgerow borders – seed mixes specifically for hedgerows can tolerate a degree of shading, supplementing the range of wildflowers already present when the cutting regime allows for the growth of woody species through the hedge.
• Woodland and shrub understorey – wildflower seeding or using plug plants to enhance existing ground cover, with management of the woody plants to ensure it does not become too shaded.
• Verges beside roads and paths - creating linear meadows where shading, fertile soils and small plots do not constrain.
• Pollinator meadow – using a mix favouring high nectar value species that would not naturally be together nor found within the local area, possibly including non-invasive garden species.
• Beetle banks – incorporated within the meadow these low mounds, seeded with tussock forming native grasses that are cut irregularly, provide important overwintering habitat for invertebrates, small mammals and reptiles.

Benefits to Nature

Wildflower meadows benefit a large number of species. The vegetation supports a diverse range of invertebrate species that depend on these as their food plants (for example caterpillars of moths and butterflies), and their flowers support a number of pollinator species.  Small mammals (especially hedgehogs and bats), birds and other invertebrates will be supported by the seeds and fruits produced by the plants and presence of prey species.  Areas of long grass allowed to die back are valuable for nesting and shelter, and areas of bare ground can be basking areas for reptiles and many invertebrates.  Birds of prey, including owls, will also forage across meadows to feed on small mammals.

With appropriate management other plant species will colonise wildflower meadows over time, and these areas can become important reserves for rare plants.  The larger the meadow that is created, the more functionally diverse the habitat that will be established.  Meadows can also provide corridors or steppingstones that facilitate species movement across the site and beyond it.  Meadows can also form important features in other habitats, for example woodland ground cover and under hedgerows, and areas of transitional and buffer habitat (such as at the edge of water, scrub or woodland).

Other benefits of wildflower meadows include water management, crop pollination and pest control, well-being and recreation.

Key Requirements

Any development site with an area of grass can establish a form of wildflower meadow, taking into account the size of the available area, surrounding habitats, soil type and local environmental conditions.  For a large meadow the whole area may not suit a single seed mix, and soil and ground type should be assessed (for example, elevated soil pH and fertility levels associated with past management practices may impede meadow establishment).  Minimising the loss and retaining existing grassland and open habitat mosaic should be the priority.

Where development incorporates undisturbed grassland, by starting an appropriate cutting regime existing species suppressed by past management can grow and produce seed.  Where the ground has been disturbed, or covered with soil from elsewhere on the site or offsite, the seed bank may have been disturbed.  If the area has been previously seeded or high performing amenity grasslands turfs laid then these can outcompete wild species, requiring the area to scarified and seeded with yellow rattle to reduce the grass dominance, or cleared.

When creating a meadow from seed or turves the species selected should be in keeping with those found within the local area, from a local source where possible, and avoiding standard mixes that may not be appropriate for the site’s ground and climatic conditions.  Ground preparation and a maintenance schedule that includes weeding of unwanted species, cutting regime, potentially some reseeding and removing cut material to reduce site nutrients will be key to its success.  Resources for management must be available to manage the meadow and keep it in good condition.

Future Management

Meadows require regular maintenance and this can be higher during their establishment and getting them into good condition.  An appropriate cutting regime is the main requirement once established.

Meadows need to be cut regularly, in many cases twice a year. The first cut is in the autumn, usually around October when the plants have set seed for the next year (checking seed pods have released seeds), the second in the early spring before flowering plants have started to grow tall.  Timings can vary to avoid some species becoming dominant.  Following cutting the vegetation should be left for several days to allow seed to drop, and then removed to maintain the meadow’s low nutrient level.  Any beetle banks are cut more irregularly, and any bare ground patches retained.

For some plants (for example primrose and cowslip) there is always an active part of the plants growing crown above the surface of the ground and the height of the cut needs to avoid damaging this.  When cutting wet meadows care should be taken to ensure the ground does not get rutted or compacted by cutting machinery.

Plants within woodland and shrub areas may not need to be cut as regularly as open grassland, but it needs to be enough to stop unwanted species from becoming dominant while not negatively effecting the plants being encouraged.  Thinning of trees and removing woody vegetation might also be required.  For hedgerows woody species such as bramble can be allowed to establish in some areas so some zones of the hedge might have different management regimes.

The meadow should be regularly inspected for non-native and invasive species that can reduce its diversity over time.  Dominant grass species can also reduce wildflower diversity as it matures, which can be managed by encouraging yellow rattle, scarifying, cutting, use of appropriate plug plants and re-seeding.

Regular surveys can be undertaken to see how well species have established and what species have come in over time.  The management regime may need revising to benefit species that have naturally established or failed to establish well, with reseeding or plug planting into the sward.

Complementary Measures

A number of measures can incorporate mini-wildflower meadows including orchards (measure 3), woodlands (measure 4), living roofs (measure 5), hedgerow (measure 7), hibernacula (measure 9) and bee banks (measure 10).  Wet meadow mix can be used in wildlife ditches and swales (measure 20) if not permanently covered by water, around biodiverse SuDS ponds (measure 21), wildlife ponds (measure 22) and rivers and burns (measure 23).

As wildflower meadows are important habitats for nocturnal insects and foraging bats, where light sources are necessary these should be wildlife friendly (measure 18).

Nature Notes

When the correct seed mix for the area and habitat is chosen and combined with a suitable cutting regime, a wildflower meadow creates a diverse and large number of flowering species, enhancing the landscape and biodiversity.  Mown paths can provide for access.  Where there is concern that a meadow might be perceived as ‘untidy’ and not being maintained, signage or interpretation boards can explain their purpose, wildlife benefit and some of the wildflower species and wildlife to look for. This will increase awareness and help build community buy in, preventing the potential for negative reaction from local users.

Further Information

• On restoring, creating and managing wildflower meadows see the Bumblebee Conservation Trust’s Grassland restoration and creation… for bumblebees, Butterfly Conservation’s Meadow creation and management video, or the RSPB’s Create a wildflower meadow
• Plantlife’s guide on Managing grassland road verges provides information of wider interest for managing wildflower grassland
• On small meadows see the RSPB’s Make a mini-meadow guidance
• On beetle banks see the RSPB’s Beetle banks guidance
• On the selection of plants see the Royal Horticultural Society’s Find a plant database (to produce a filtered list of native wildflowers)

Orchards consist of five or more fruit or nut trees that are planted for the food they produce, often with a mix of different species and variety of fruit trees.  They can be planted in larger gardens or communal green space shared by users of a site, or a community orchard can be established.  Existing traditional or old growth orchards can be found on sites subject to development, and these can be brought back into condition with pruning, taking grafts to establish new trees of the same variety, and reintroducing management.

Orchards are more than the trees, with an understorey that can be sown and managed as a meadow, fallen trees and log piles providing deadwood features, and often enclosed by a hedgerow (containing flowering shrubs such as hawthorn and dog rose) or wall.

Benefits to Nature

Orchards can be exceptionally species rich environments, with the most valuable comprising multiple trees of multiple species.  They provide important floral resources (especially for early season pollinators), and a large number of invertebrate species like this type of habitat or feed directly from the trees.  The fruit borne by the trees in autumn provide an important sugar source for late season insects and food source for birds, with larger fruits lasting in to the winter. 

As orchard trees grow and mature they provide a suitable substrate for many species of lichen and moss to grow on, with many of conservation interest reliant on this type of habitat.  Old growth orchard is of special importance and particularly difficult to replace.  Veteran trees can also contain rot holes and sap runs, providing feeding and nesting habitat for a wide variety of birds and invertebrates.  Many insects and their larvae will feed on the tree’s foliage, and ultimately support their predators, including small mammals and birds.  The ground flora and flowering shrubs in any attached hedgerows also provide important sources of additional nectar for dead wood invertebrates (which are often not very good dispersers).

Other benefits of orchards include absorbing air pollutants, carbon capture, crop pollination and pest control, providing shade and cooling, water management, food provision, well-being and recreation.

Key Requirements

Orchards can be very variable in size, from as few as five fruit trees in a garden or on a small site, to multiple groups of trees on a larger site.  The soil must be of adequate depth and type to support the trees, and avoid frost pockets where possible.  The trees will need to be protected from browsing animals, such as rabbits or deer.  The ability to manage the ground cover and undertake regular pruning is required, which will be greater for old growth orchards.

Future Management

When orchard trees are first established watering may be required until they are well established.  A schedule of yearly pruning will encourage the trees to develop the best form for bearing fruit, and produce strong fruit crops.  Rejuvenating an old growth orchard may require harsher pruning to restore the health of the trees, and more understorey management to remove any weedy or invasive species which have become established.  Any replacement trees should be of similar varieties where possible, with consideration given to taking cuttings from the original trees (to protect historic varieties).

Any other biodiversity measures incorporated into the orchard, such as bird boxes, will need to be maintained as required.

Complementary Measures

A large number of other measures can be incorporated in an orchard, including bee boxes and bricks, and a bee bank (measure 10) where there is a large enough open space with direct sunlight without canopy cover.  Bee species that use these are some of the best pollinators of fruit trees.

Log and leaf piles (measure 8), hibernacula (measure 9), bug hotels and boxes (measure 11) and hedgehog houses (measure 12) will encourage invertebrates, amphibians and small mammals that predate on other invertebrate species that could cause damage to the orchard, providing a natural pest control.  Bird and bat boxes (measures 13 and 15) can be placed on older orchard trees that are able to support their weight, or on trees or structures nearby, with young birds especially preying on potentially damaging caterpillar species.  As orchards can be important habitats for nocturnal insects and foraging bats, where light sources are necessary these should be wildlife friendly (measure 18).

A wildlife wall (measure 16) or hedgerow (measure 7) can be used to establish the orchard’s perimeter and provide shelter.  A wall also provides basking areas for many invertebrate species, and the hedgerow can complement the orchard’s resources for pollinators and predators.  The understorey of the orchard can be sown with a wildflower meadow mix (measure 2).

Nature Notes

Old growth orchards are valuable historic and biodiversity features that usually support a large diversity of wildlife.  However they have been in rapid decline in our landscape, and where neglected their trees can take several years to return to good condition.  Where development includes an old orchard its protection and enhancement should be prioritised where possible. 

New orchards, even small ones, will enhance biodiversity, and can become an important community feature.  Even small orchards will produce fruit that will be well received by the community (leaving some for wildlife), providing an opportunity for promoting the connections between people and nature, supported by interpretative materials where appropriate.

Further Information

• On planting and enhancing an orchard see NatureScot’s Garden for orchards to help local wildlife guide and the Woodland Trust’s Orchards guide

• For a wide range of advice, information and practical management guides see The People’s Trust for Endangered Species Traditional orchards project

Trees take many years to establish and provide good habitat, and retaining and enhancing existing trees, scrub and woodland wherever possible will be of greatest amenity and biodiversity value.  Veteran trees are particularly rich in biodiversity, and should be incorporated within the planned development and protected from damage during construction, especially the root zone.

But planting trees and woodland, or allowing them to regenerate, can provide an important enhancement for biodiversity, and enhance connectivity both on- and off-site.  Native trees appropriate to the area should be prioritised as these will support the most wildlife, but non-natives can benefit biodiversity when their flowers, fruits, berries and seeds can be utilised by wildlife (avoiding any that could self-seed and become invasive). Trees can be incorporated in a variety of forms, including individual trees, rows of trees, a small copse, mini woodland or more extensive woods.

• Street trees can be planted in tree pits along roads or pavements, and within gardens or grounds beside them.  Lining a route provides a corridor for wildlife to move through development, connecting landscape planting, hedgerows, woodland and greenspace on- and off-site.  Feature trees can be planted in groups or corridors, providing benefits for sustainable urban drainage schemes and urban cooling, as well as biodiversity.
• Scrub is formed of low growing woody species and immature trees that will eventually grow into woodland, or planted as a transitional zone on the edge of existing or created woodland.  It can provide shelter for development, and dense scrub can protect habitats from light, noise and air pollution, and discourage public access with thorny species.   
• There are many different types of woodland, depending on the ground type, species and local environment conditions.   This can include riparian or wet woodland species that enjoy wetter conditions (such as alder and willow), planted at the edge of wetland or water features.  The value of the existing habitat that will be replaced by trees, its availability within the area and species using it needs to be considered, and improving connectivity where possible with on- and off-site woodland.

Benefits to Nature

Native tree species support a large number of native species, providing leaves for invertebrates to feed on, floral resources especially for early season pollinators, berry and seeds for birds (particularly important for winter migratory species).  They also provide shelter, roost and nest sites, and can connect habitats within and around development.  Biodiversity generally increases as trees mature and woodland develops a diverse understorey and ground cover, including deadwood, which supports significant populations of invertebrates.

Scrub is very valuable for biodiversity, providing dense areas of early flowers for a range of pollinators, a large amount of fruit for many winter thrush species, and a large number of insects feeding on the scrub that are prey for others.  It also provides a key nesting area for many birds.

Small mammals gain foraging and shelter (and larger mammals in bigger woodlands), including hedgehogs, red squirrel and pine martens.  The tree species themselves and certain woodland types can be a priority for action in Local Biodiversity Action Plan, for example establishing new areas of Aspen.  Riparian woodland is also a key contributor to the aquatic system, as an important source of organic matter supporting invertebrates, providing shade that helps regulate light levels and water temperature, and shelter for emerging semi-aquatic insects, particularly important for the development of chicks fed on flying insects and a prey for bats and fish.

Other benefits of trees, scrub and woodland include absorbing air pollutants and noise, carbon capture, providing shade and cooling, screening light pollution, water management, well-being and recreation.

Key Requirements   

Street and feature trees can be planted where space only allows for a single tree if soil of suitable depth and type is present, with space for growth over time.  A large enough area of living soil around the tree should be left unpaved so that it can properly feed and support the tree, with permeable and semi-permeable surfaces allowing enough water to reach their roots.  Its water requirements will change over its life cycle, and the extent of their roots and impacts on other street infrastructure requires consideration.

A woodland requires an area large enough to include multiple trees of a mix of species, and ideally with scrub around its edge transitioning in to meadow or grassland.  A smaller area may be able to accommodate just scrub planting, or scrub with a few emergent trees.  The trees need to be spaced out to allow enough light to penetrate and sustain ground cover and scrub (requiring less space, ‘Wee Forests ’ are high density, native species pocket sized woodlands).  The soil depth and type must be suitable for the selected tree species.

Tree, scrub and woodland planting require careful species selection to avoid future issues, such as unwanted screening of views or casting of shade.  If there are concerns with heavy leaf litter fall, selecting species with smaller leaves and leaf burdens and a faster rate of leaf decomposition can mitigate this.  Locally grown trees of local provenance should be used where possible to protect the local genetics of native species and reduce the risk of pests and diseases being accidently transported into the area.

Future Management

Street and feature trees may require watering when first established (especially in dry weather), weeded and any tree stakes and guards regularly checked and adjusted.  Tree guards (preferably biodegradable to reduce plastic waste), should only be used when there is a risk of herbivore grazing damage, and removed once the risk of browsing damage has been passed.  Trees should be regularly checked to ensure they remain healthy and disease free, and any trees that die replaced and damaged limbs removed.

Woodland planting trees will need to be checked to ensure they are established, losses replaced, tree tubes or supports adjusted and eventually removed.  Where there is high grazing pressure either from wild or domestic herbivores, fencing (appropriately marked where there is a high risk of bird collision) and its maintenance may be required.  As trees become established it may be necessary to thin them or prune branches to ensure adequate spacing and enough light reaches ground cover plants.  Deadwood is a key component of the woodland ecosystem, and cut or fallen wood should be retained to create dead wood features such as log piles.

Seeding, planting of plug plants and selective cutting may be required to help the ground storey establish.  A healthy woodland should develop several levels of understory within its structure.  The woodland edge should not be heavily managed, as it will be more valuable if shrubs are allowed to flower and fruit freely, without being cut back.  Regular inspections should be made of the planted and surrounding area to locate and remove any non-native invasive species.

A woodland management plan should be prepared addressing the protection of existing trees and scrub, natural regeneration and encouraging a diverse understory, retaining open glades, management of standing and fallen deadwood and any invasive non-native species, and maintenance of other measures such as bird or bat boxes.   The plan should include a protocol for ensuring any future factor or grounds manager is aware of the plan.

Complementary Measures

Street trees if large enough can hold bird and bat boxes (measures 13 and 15), but only on quiet roads and where the entrance and main movements to nearby trees and other foraging habitat will avoid the road when entering and leaving the box.

As it will take some years for woodland to mature, other measures should be considered for enhancing biodiversity while the trees are young.  Log and leaf piles (measure 8), hibernacula (measure 9), and bug hotels and boxes (measure 11) can increase the niches available in newly created or existing areas of scrub and woodland.  Hedgehog houses (measure 12) can be used where there is sufficient shelter, or placed within a log and leaf pile.  Woodland and scrub provides foraging habitat for hedgehogs and other small mammals, and should be connected with other habitats by incorporating in to a hedgehog highway.  Woodland can be planted with a wildflower meadow understory (measure 2).

Planted trees will not initially support bird, owl or bat boxes (measures 13, 14 and 15), but these could be placed on structures or poles within or near to the area.  A future woodland pond (measure 22) can be created around which the woodland will grow, creating an additional rich habitat, and riparian woodland established with rivers and burns (measure 23).

Nature Notes

Trees and woodland form a complex ecosystem, providing forage, shelter, roost and nest sites for a wide variety of species.  The understorey and deadwood are important components, and deadwood alone provides an essential resource for over 2,000 invertebrate species.

Woodland and scrub habitat can provide a range of nature-based solutions, including blocking light pollution, absorbing noise pollution, providing shelter for development, capturing air pollutants and soaking up excess water.  Woodland is also highly valued for the fruit, berries and amenity it provides to people, and where appropriate public access with interpretation can be planned from the outset.

Further Information

• For information on native tree species and value to wildlife see the Woodland Trust’s A – Z of British trees, and the Royal Horticultural Society’s Find a plant database (to produce a filtered list of native trees suitable for different conditions)
• On establishing a small woodland or scrub see The Wildlife Trusts’ How to make a woodland edge garden for wildlife and How to make a shrub garden for wildlife
• For general advice and information on street trees see Forest Research’s Resources Street trees
• For guidance on incorporating trees into development see The Woodland Trust’s Residential developments and trees A guide for developers and planners

Living roofs come in a number of different forms, but all incorporate a growing medium that supports plants and possibly other habitat features.  They can be included on residential, commercial or public buildings, and minor structures such as bus stops, maintenance sheds, bike stores and bin sheds.  Living roof types are distinguished by the level of management they require, which reflects the depth of substrate and species growing.

Extensive Green Roofs: Sedum, Wildflower and Biodiverse

Extensive green roofs have a shallow substrate (6 – 15 cm deep), require limited maintenance, no irrigation system and usually do not provide for general access.  Their installation on a building generally includes, in order, a thermal insulation layer, waterproof liner with protective layer sealing the roof, water retention mat that allows rain water to be stored with a filter fleece preventing soil contamination and drain for excess water, covered by a soil layer.  Utility structures such as bike and bin sheds have a simpler construction, often with bee, bug and bird boxes fixed to their sides.

A sedum roof is one of the simplest and lightest green roofs, incorporating 6 - 8 cm of soil.  A sedum ‘carpet’ can be laid on the soil layer or plug plants used, and other shallow rooted species introduced amongst the sedums to enhance biodiversity.  A wildflower roof incorporates a deeper 8 – 15 cm soil layer to provide suitable rooting depth for taller wildflower species (from seed, plug plants or wildflower turf).  A short lawn mix or other drought tolerant seed mix could be used where occasional drought is likely to be an issue.

A biodiverse roof is similar to a wildflower roof, but instead of a uniform substrate it varies in depth between 8 – 15 cm to form small dips and hummocks, and incorporates gravel, stones and dead wood.  Dips can be lined with stones and rocks to form small temporary pools during heavy rain, and hummocks planted with deeper rooted species. This can be sown with seed, planted with plug plants or laid with wildflower turfs.  When the soil is unplanted to allow colonisation from windblown seed and seeds in bird droppings, these are known as brown roofs.

A solar biodiverse roof is similar to the above but with the addition of rows of angled solar panels upon metal frames.  A deeper substrate of 10 – 20 cm can help sustain deeper rooted and less drought tolerant wildflower species, and the shade from the solar panels creates sheltered microclimates and damper areas for invertebrates.  Where drought is a particular threat then more drought resilient species can be planted.  The plants on this form of green roof help cool the solar panels, making them up to 8% more efficient.

Intensive and Semi Intensive Green Roofs

A semi intensive green roof has a soil layer of 12 – 25 cm, allowing larger perennial and woody species as well as small scrub species to be planted, or drought tolerant plants if needed.  An intensive green roof has a much deeper soil layer of up to 1 metre, and can support almost any size of vegetation including appropriate tree species.  Blue green roof elements can be included to store water and lessen the need of larger plants for additional watering.  These roofs can be used for creating semi-formal garden, food growing and connected leisure spaces if they are accessible.

Blue Green Roofs

These roofs provide for additional rainwater retention by incorporating a void to retain water between the waterproof liner and standard reservoir layer above, with an overflow to prevent the soil layer from being flooded.  The soil depth will vary depending on the wildflower, shrub and tree species desired, and more drought tolerant plants may still be required in dry areas.   Areas of open water can also be formed with small ponds fed by the rainwater store.

Benefits to Nature

While not confined to urban areas, these features can act as important stepping stones that enhance connectivity in towns and cities for a wide variety of species, especially invertebrates and pollinators.  The use of stones can provide invertebrate basking areas, and dead wood more shelter.  Green roofs can also provide important habitat for many bird species, including some waders that will use them for nesting.  

Planting with a wide range of native species to support the greatest diversity of species will maximise a green roof’s biodiversity potential.  Native wild plants can be selected to support local priority species, providing an important haven and helping their spread through the local area.

Other benefits of green roofs include slowing water runoff, controlling excess water, moderating building temperature, urban cooling and absorbing air pollutants (especially from road traffic).

Key Requirements

Living roofs can be incorporated on any size of roof space where its additional weight can be taken by the structure and the roof remains impervious, which requires specialist design and structural advice.   As they are designed to retain water on the roof its water proofing must be appropriate for the conditions under a green roof. 

Access to water during dry periods, and for the intensive roofs an irrigation system, will be required other than for the more drought tolerant species and those that are allowed to die back and reseed.  The more complex the vegetation the more irrigation will be needed.  Access for managing vegetation will be required, particularly for intensive green roofs.

Small utility structures may be able to add an extensive green roof more easily as long as its structural strength is adequate.  These will be lighter, incorporating a sedum, wildflower meadow or brown roof, with less water retaining capacity.

Future Management

Plants on a living roof will require annual management that should be set out in a maintenance plan.  This includes the cutting and pruning of planted species, weeding unwanted and thinning dominant species, removal of any inappropriate woody or deep rooted species to prevent damage, and monitoring and eradication of any invasive species (especially on roofs where self-seeding is encouraged).  If planted or seeded species fail or plant diversity declines replacement species more suited can be introduced.  Intensive roofs will require greater effort, and solar biodiverse roofs will need to be managed to ensure vegetation does not interfere with the solar panels.

In dry periods irrigation will be required depending on the type of vegetation and species planted.  Extensive roofs where dieback is of concern may require occasional irrigation, but intensive roofs with deep soil and larger plants will require more regular irrigation.  Green roofs on utility structures with their thin soil may require regular watering during a dry period.  Where an irrigation system is built in this needs to be maintained and monitored to ensure it is functioning.

Complementary Measures

Log piles (measure 8), bee bricks, boxes and banks (measure 10) and bug hotels and boxes (measure 11) can be placed in sheltered areas and preferably fixed to the roof where they cannot be knocked or blown off.  Bird and bat boxes (measures 13 and 15) can be placed upon the roof or structures that are on the roof.  It might also be possible to build structures as part of the green roof to secure these.

Living roofs can support many of the plants for pollinators (measure 1) and species found in wildflower meadows (measure 2), where they can adapt to a thin soil.

Nature Notes

Butterfly Conservation Scotland have run a project encouraging the planting of Common rock-rose across Edinburgh to support the rare butterfly Northern Brown Argus found on nearby Arthur’s Seat.  This food plant has been included on green roofs across Edinburgh including the Scottish Parliament building, providing habitat stepping stones across the capital.  A similar approach could encourage dispersal of other wildlife with the selection of appropriate plants.

Further Information

• On their design, installation and maintenance see The Green Roof Organisation’s Green Roof Code 2021
• On designing and managing green roofs for bugs see Buglife’s Creating green roofs for invertebrates
• For more background and case studies see The Scottish Green Roof Forum’s Green roofs part of Scotland’s sustainable future, Livingroofs.org website, NatureScot’s commissioned Meadowbank development green roof options appraisal, and the Greater London Authority’s Living roofs and walls from policy to practice

Green / Living Wall

These consist of a structure on the outer wall of a building supporting containers, shelves or pockets with plants, usually with a hidden irrigation system to ensure the vegetation remains watered. The plants can be selected to include flowers for pollinators and seed and fruit for birds, and absorb pollutants from busy roads, taking care to avoid potentially invasive species.  Bee, bug, bird and bat boxes can be incorporated in the green wall.

Green Screen / Facade

These are a fence or trellis like structure supporting climbing plants and tall shrubs planted in the ground.  Flowering and fruit bearing plants will support pollinators, taking care to avoid potentially invasive species that may have negative effects upon the surrounding habitat.  Green screens can be used to hide unattractive areas (for example bin sheds), and absorb pollutants from roads next to a development.  Bee, bug, bird and bat boxes can be incorporated in the green screen.

Benefits to Nature

Depending on the plant species selected, their number and diversity, green walls and screens can benefit a range of species.  This includes providing important resources for pollinators and where fruit producing species are planted, food for birds.  The vegetation also provides food for invertebrates and shelter and breeding space that can be limited in urban areas for a range of species.  As green walls and screens in urban areas provide areas of vegetation where there is usually none, they enhance connectivity by providing essential stepping stones for species.

Other benefits of green walls and screens include absorbing air pollutants (especially from road traffic), managing excess water (if using a recycling system), moderating building temperature and contributing to urban cooling. 

Key Requirements

Green walls require a wall substantial enough to take the weight of the structure, growing medium and plants, and access to water for the irrigation system. Where the wall covers multiple storeys, specialist engineering will be needed to waterproof the structure and take the weight.  Access to erect the green wall and undertake future management will be essential.  At a smaller scale, green walls can be incorporated into small boundary and feature walls where suitable irrigation can be provided.

Green screens are easier to put in place as a much less substantial structure is required.  They can be used on many developments, but cannot be as tall as a green wall.  Plants must be suited to the site’s soil type and conditions.  Some types of wall may be damaged by certain climbing species so careful consideration of species used and the wall’s finish must be considered.

Future Management

A green wall on a building is a specialist structure whose components will require maintenance as specified by its designer.  The irrigation system will require inspection to ensure it is both functional and delivering an adequate water supply to all plants.  Vegetation will also require checking during maintenance inspections, with struggling, diseased or dead plants replaced, and any unwanted self-seeded species removed.  Other biodiversity measures on the wall such as bee, bug and bird boxes will also require checking.

A green screen needs regular checking to ensure it remains stable, secure and in good condition.  Plants can be inspected as required from ground level, and any struggling, diseased or dead plants replaced, and unwanted species removed.  Pruning may be required to avoid interference with guttering or windows.  Other biodiversity measures incorporated on the screen such as bee, bug and bird boxes will also require checking.

Complementary Measures

Bee bricks and boxes (measure 10), bug boxes (measure 11), bird boxes (measure 13) and bat boxes (measure 15) can all be incorporated into green walls and screens to provide additional habitat niches.  A wildlife wall (measure 16) can be added at the base of a ground level green wall or incorporated into a green screen by growing climbing plants up the wall or planting plants into the wall.

Nature Notes

Where ground space is limited on a development site, by utilising vertical space green walls and screens can increase the amount of planted space considerably.  While there can be concerns with climbing plants on buildings, in practice this is not an issue if the wall is sound and selected species are appropriate.

Further Information

• On creating a green screen and selecting climbing plants see the RSPB’s Cloak your walls with climbing plants, and the Royal Horticultural Society’s Find a plant database (to produce a filtered list of native wildlife and pollinator friendly climbing plants that can be used in creating green screens)
• For general advice and information see The Scottish Green Infrastructure Forum guidance on creating green walls and the Livingroofs.org website

Hedges can be used to demarcate the internal and external boundaries of a development, screen light and noise pollution, and contribute to access management.  Existing species-rich hedgerows are extremely valuable for biodiversity, and given the time required to mature they should be protected and retained within the development where possible, even if in poor condition.

Native Hedge

A native hedge comprises hedge species that are native to the area in which it is planted, including its understorey and emergent trees.  The species will vary dependent on site conditions, but can be selected to support particular wildlife.  This includes multiple flowering species to benefit pollinators, encouraging climbing species like dog rose and brambles to create additional shelter (as well as flowers and fruit), and planting a wildflower margin either side of the hedgerow (providing a necessary buffer between paths and other uses).  

Creating a dense structure to the hedge is important for providing nest sites within it, and understorey planting can create shelter for many ground nesting species.  Establishing a hedge on a raised bank, and in association with a ditch provides more diverse habitats for invertebrates.

Amenity Hedge

Amenity hedges may include native and non-native species, of one or more species.  Beech and hornbeam are commonly planted, but do not provide flowers for pollinators, produce no berries, few species are able to eat the foliage and ground flora can be limited.  Species like Rosa rugosa, cotoneaster and laurel do support wildlife but can be invasive in some habitats and particularly damaging.  Other non-native and native species can be used to achieve high biodiversity value while avoiding these risks.

Benefits to Nature

Hedgerows can benefit a very large number of species but this will vary depending on its species composition and siting.  In general the use of native species and greater diversity will tend to be of more biodiversity benefit, which can be enhanced where trees are allowed to emerge from the hedge (further supporting insects and providing nest sites when mature).  They can also provide important corridors for wildlife to move around a development site and connect existing and new areas of habitat within the development and with adjacent areas.

Native hedgerows are important habitats for invertebrates, pollinators, mammals and birds, providing shelter, food, roost and nest sites, and corridors for movement.  They can provide hunting for bats and birds of prey, and their fruit can be an important food source for winter migratory birds.  They also act as large reservoirs of invertebrates (over 1500 insect species have been recorded on hedgerows), and large mammals like fox and badger will use hedges for movement and for constructing setts.

Amenity hedgerows can support a range of wildlife with careful choice of hedging species, especially for pollinators (from bees, wasps and hoverflies to moths, butterflies and beetles), and will provide shelter and corridors for movement (such as hedgehogs).  Evergreen hedges provide shelter throughout the year.  The commonly planted monoculture beech hedge provides good shelter (as it retains its leaves over winter), but toxins in the leaves limit the undergrowth and the insects that can be supported. Of greater benefit are hedgerows with a wider variety of amenity species with vegetation more palatable to insects (particularly important for many insect larvae), have flowers which can support pollinators, produce fruit for wildlife and encourage an understorey attractive to wildlife.

Other benefits of hedges include absorbing air pollutants and noise, carbon capture, providing shade and cooling, screening light pollution, managing access (utilising thorny species), water management, and well-being and recreation.

Key Requirements

Hedgerows can be used to establish external boundaries or create internal divisions of whatever length that is required.  The site requires suitable soil type and depth to sustain the hedgerow species selected, although the large range of potential native and amenity species means this is unlikely to be a constraint.  Established hedgerows require protection during the construction phase from machinery and materials storage compacting their root zone. 

Hedgerows require some management to keep them in the best condition for biodiversity, but heavy management (especially harsh cutting) can reduce flowering and fruiting. Native hedges require more space but less disturbance for management.

Locally grown stock of local provenance should be used where possible to protect the local genetics of native species and reduce the risk of pests and diseases being accidently transported into the area.

Future Management

Regular inspections of the hedge to remove litter and check for invasive species that can lead to a loss of structure and species diversity are required.  Pesticide use and digging within the vicinity of the root zone should be avoided.  Pre-existing but poor quality hedges may require planting of new shrubs to fill gaps and seeding a hedge meadow mix at its base.

Once established, hedges benefit from careful cutting and pruning to retain a dense vegetation structure, and avoid thinning over-time.  They do not need to have a uniform shape or height, and varying the location and frequency of cutting by leaving different sections uncut each year to flower and fruit will support greater biodiversity.  Cutting should be carried out in winter and avoid March to August to prevent disturbance of nesting birds.  Mature hedges require laying to maintain their structure and enhance biodiversity. 

Where meadow species comprise the hedgerow understorey they may require cutting (in autumn after seed sets and in spring before growth starts), ensuring shrub and tree species are not damaged.  Any other complementary measures incorporated in the hedgerow will also require maintenance.

For larger developments a long term management plan that takes account of the need for changes in management as the hedgerow matures is advised.

Complementary Measures

Log and leaf piles (measure 8), bug boxes and hotels (measure 11) and hedgehog homes (measure 12) can be placed in sheltered positions in existing or newly established hedgerows, or added later as the hedgerow matures.  Hibernacula (measure 9) can be placed along the base of the hedge outside of the root protection zone to avoid disturbing its roots.  These add structures and niches within the hedgerow, and provide more overwintering shelter.

Hedgerows can be a component of hedgehog highways (measure 12).  Wildlife friendly lighting (measure 18) should be used as hedgerows provide a valuable foraging and transit corridor for many nocturnal insects and small mammals, including bats.  Wildlife ditches and swales (measure 20) can also complement hedgerows, ensuring that it is dug outside the root protection zone of an existing hedge.  Meadow wildflowers (measure 2) can be sown in a strip alongside hedges, as well as under them to create an understorey layer with a tailored hedgerow mix, providing an additional food source for a wide variety of species.

Many types of small bird box (measure 13) other than swift, swallow and house martin boxes can be placed within the hedge or on emergent trees, as long as there is access to the box entrance for the birds and maintenance.  Open fronted nest boxes particularly benefit from the additional shelter provided within the hedgerow.  Barn owl boxes (measure 14) and bat boxes (measure 15) can be fixed to mature emergent trees or a pole within the hedgerow.

Orchards (measure 3) can have a native hedgerow boundary around them, providing shelter for young fruit trees and additional resources for pollinators after they have flowered in the spring.  They also provide over wintering shelter for pollinators and insects that can control damaging herbivore outbreaks in the orchard.

Nature Notes

Hedgerows are in serious decline within the landscape as a result of removal and poor management.  They are often cut and pruned regularly, but this can result in dead and less dense areas, reducing the shelter they provide.  Cutting can remove seed and berries as well as flowers of the coming season, and many invertebrates lay their eggs on new buds.  Mechanical flailing often removes emergent hedgerow trees.  Regular cutting can also damage flower and fruit production if undertaken at the wrong time of year, and careful consideration of the cutting regime is required.

Further Information

• For a wide range of advice on creating and managing hedgerows see Buglife’s Ancient and species-rich hedgerow guidance, and Hedgelink’s Resources
• On creating and managing garden hedgerows see the RSPB’s Best hedges for wildlife
• On the selection of plants see the Royal Horticultural Society’s Find a plant database (to produce a filtered list of native wildlife and pollinator friendly hedgerow species)

These features are loosely organised pile of logs and / or leaves that create a habitat of slowly decaying wood and leaf litter.  The material should be sourced on site (or from as close as possible), for example using cut material from pruning, thinning or felling of trees for safety reasons, to reduce the risk of spreading pests and pathogens.  Where existing habitats (especially hedgerows, scrub and woodland) contain deadwood, these are already important biodiversity features and both standing and fallen deadwood should be retained.  Standing deadwood that has to be felled for safety reasons should be created into deadwood features on the ground.

Log Pile

A shallow scrape is dug in the ground which is lined with leaf litter or wood chips.  Logs of varying sizes are arranged irregularly on top of this to create a wide range of different sized voids and entrances.  Smaller logs and twigs can be placed in gaps, and leaf litter or bark chips added over the top.

Leaf Mulch Cage

An open-top cage is created from wood posts and chicken wire and filled with leaf litter or other mulch materials.  On one or two sides of the cage a 13 cm gap is left between the ground and side wall to provide access to the decayed leaf mulch for small mammals and amphibians, and for extracting garden mulch if required.

Leaf Litter Pile

An area is designated for the leaf pile and then fallen leaves are continuously added. More structure can be provided by incorporating this with a log pile. The difference from the leaf cage is the pile is less contained and not developed to allow harvesting of leaf litter mulch for gardens.

Benefits to Nature

These provide food and shelter for a very large range of invertebrate species, small mammals, birds and amphibians.  They can be particularly important for hedgehog and reptile hibernation, and amphibian species.  Many insectivorous bird species will use these as foraging habitat, and reptiles can use exposed logs for basking.

The invertebrates supported include species that help to recycle decaying mater and predators controlling the outbreak of pest species.  They can also be important for pollinator species, especially moth and butterflies, with some using them to hibernate and pupate in.

Key Requirements

Requiring 1 – 2 meters squared, several log piles, leaf mulch cage and litter piles can be easily established across a site depending on the scale of the development.  No specialist skills are required for their construction or maintenance.  Each requires a site with minimal disturbance and at least partial shading to reduce drying out and restricting the invertebrate habitat (for log piles bark chips and leaf litter can help contain moisture).  Siting in different habitats with different levels of shade will support more biodiversity.

Leaf piles and mulch cages similarly require a shaded site with minimal disturbance. As leaf mulch rots down (or is sensitively harvested from the base), new leaf material must be added to the top.

Future Management

Upon handover of the development to owner / factor, the location, purpose and maintenance of these features should be clearly documented.  Deadwood management should be built into any management plans to ensure such features are not removed by future management actions.

All three features will require new wood or leaf material to be added as the original material decays, using material collected on site (avoid the addition of grass clippings as they can result in anaerobic conditions and reduce diversity).  Leaf piles may require additional leaf litter added more regularly or built up in the autumn as it will decay faster.  If mulch is to be harvested for gardens from leaf mulch cages this needs to be done carefully so as not to disrupt the habitat and should avoid hedgehog breeding and hibernation periods.

Complementary Measures

All three features can be incorporated in to hedgerows (measure 7), woodland and scrub (measure 4) and orchards (measure 3), enhancing the habitat niches available to support a wider range of species.  These features can also provide shelter along hedgehog highways and near to hedgehog houses (measure 12), especially for over wintering.

Log or leaf piles can be created on top of buried hibernacula features (measure 9), or incorporated around ponds (measures 21 and 22) to provide year round shelter for amphibians and other invertebrate species (especially to over-winter in).  They can also be placed in rain gardens (measure 19) and alongside swales and ditches, rivers and burns (measures 20 and 23) to shelter over-wintering species and damp loving species during dry weather.

Log piles can be placed on to living roofs (measure 5) where it is safe to place these.

Nature Notes

There can be some worry about these features encouraging large number of rats and mice, but their appropriate management should avoid this.  Food waste must not be added to any of the piles, as these are not to act as traditional compost heaps and this extra food resource can increase small mammal numbers to a high level.  Similarly these should not be placed in an area where litter could accumulate, near bins, waste disposal or traditional compost areas.

It is also key to remember that small mammals (especially mice and shrews) can be valuable in controlling pest insects by preying on the species causing the issue. They are also a critical food source themselves for owls and other birds of prey.

Further Information

• On creating a log pile see RSPB’s Create a log pile for wildlife and The Wildlife Trusts’ How to make a log shelter
• On creating a leaf mulch cage see RSPB’s Create a leaf-mould cage

On creating a leaf pile see People’s Trust for Endangered Species’ How to make a leaf pile or leaf mould and How to make a mulch pile

A very wide range of features can be used as hibernacula (a winter shelter for hibernating animals), such as log and leaf piles (measure 8), but the features listed here are those which are buried in part or full.

Underground Hibernacula and Rock Pile

A hole is dug in the ground and a layer of stones placed on the floor, followed by logs and twigs (and possibly more rocks), to create a chamber within the hole.  This can be built up to ground level or higher to form a mound (which could provide a bee bank), and covered with soil but leaving access to the covered chamber (access can be achieved by including short sections of pipe).  A rock pile is a variation, filling the hole with a range of rocks and stones to provide different sized voids, and left uncovered.

Beetle Bucket

A miniature version of the underground hibernacula uses a bucket.  Holes are made in the side of the bucket to give ground dwelling insects access, and drainage holes are made in the base. The bucket is then filled with stones in the base and logs stood on their ends, with the gaps in between filled with twigs and stones. The bucket is buried in a hole with a thin layer of soil over the top.

Benefits to Nature

These provide habitat and shelter for a wide range of invertebrates, small mammals, amphibians and reptiles, and can be particularly important for the latter two when placed near ponds and water courses.  They can be especially important for providing over-wintering hibernation sites for pollinator and predatory species.  Other benefits include pollination and pest control.

Key Requirements

Requiring as little as 1 metre squared, a number of hibernacula can be easily established across a site.  No specialist skills are required for their construction or maintenance, which can often utilise site or otherwise unused construction materials.  Each requires an area of ground that will remain undisturbed and not be driven over by machinery for access, and avoid areas at risk of flooding, as hibernating animals could potentially drown.

Hibernation sites tend to be on south-facing slopes, and should avoid disturbing tree root systems and crevices in banks that may support reptiles,  An area with some shade and ground cover is best suited to avoid drying out (this is of less concern where a bee bank is constructed on top).  For rock piles particularly some direct sunlight can help it act as a basking area for insects.  Siting in different habitats with different amounts of shade will support more biodiversity.

Future Management

As these features are largely buried and unobtrusive it is particularly important to ensure at handover of the development to the owner / factor that the location, purpose and maintenance of these features is clearly documented.  This should ensure that they are kept free of both vehicle and foot traffic, as their weight could collapse the hibernacula beneath.

Only a low level of management is required, to ensure entrances into the hibernacula are kept clear of blockages to allow access.  Rock piles need to be kept free of encroaching vegetation to leave the area clear, and allow sunlight to penetrate.

Complementary Measures

Buried hibernacula and beetle buckets can have log or leaf piles placed on top of them (measure 8), and if built into a mound this can be turned into a bee bank (measure 10).  They can be built into hedgerows (measure 7), and placed within scrub and woodland (measure 4) to provide further structure within the habitat to support small mammals and invertebrates.  Where new scrub and woodland habitat are being planted time is needed for these niches to develop naturally, and introducing hibernacula can therefore speed this up.

Swales and ditches, biodiverse SuDs ponds, wildlife ponds, rivers and burns (measures 20, 21, 22 and 23) can have these features incorporated around their edges, far enough from the water features to make sure they do not flood. These can act as year round shelter for amphibians, reptiles and invertebrate species.

Rock piles can also be established in open areas as many species can use these as basking areas as well as for shelter. These can be incorporated particularly into wildflower meadows (measure 2) to allow basking.  Small rock piles can be incorporated into bee banks (measure 10), though care has to be taken to leave enough areas of wildflowers and still provide areas of bare ground.

Nature Notes

These features will support small mammals such as mice and shrews, which feed on invertebrates including those that can become pests.  Small mammal species are themselves important prey for many other species, including birds of prey such as owls.  While there can be some concern that larger hibernacula features could lead to large numbers of small mammals like mice or rats, with appropriate placement and management this is unlikely to be the case.  However they should not be placed near compost heaps containing waste food, near bins or where litter is likely to accumulate.

Further Information

• On creating a hibernaculum see the RSPB’s Make a house for frogs and toads
• On creating a rock Pile see the RSPB’s Make a rock pile
• On creating a beetle bucket see The Wildlife Trusts’ Make a beetle bucket and the RSPB’s Make a beetle bucket

These features provide small tube like tunnels, 2 – 6 mm in diameter and around 15 cm long, that solitary bee and wasp species require for nests. These bee species do not have ‘worker bees’ serving the nests like social bees, meaning nests are small and contained within the feature.

Bee Bricks

A bee brick is a pre-cast brick containing a number of tube like tunnels.  The bricks, which are available in a range of shapes, sizes and colours, can be used in the walls of buildings, boundary walls or other structures.

Bee Boxes

A bee box is a wooden box similar to a bird box but with no front, that can be attached to a building, structure or tree. The inside of the box is filled with cut bamboo canes and blocks of wood with holes drilled in them to create tunnels.

Bee Bank

A bee bank is a simple bank or mound of earth that has ledges cut into it that are covered in sandy soil. These ledges are kept clear of vegetation to provide the bare ground required by tunnel nesting insects such as solitary bee species. The rest of the mound can be seeded with a wildflower mix, providing a local food source. Their size can vary, with large mounds incorporating vertical ‘cliffs’ of bare ground.

Benefits to Nature

These support tunnel nesting insects, particularly solitary bees and species of hunting wasps, and a large number of invertebrate species requiring bare ground, or using tunnels for shelter and hibernation.  When established with wildflowers, these can provide pollen and nectar for bees, wasps and other invertebrates, and provide pollination more widely.  The specialist bees using these types of nest are good pollinators of fruit and berry producing plants, and hunting wasps are key predators of many pest species.

Key Requirements

Multiple bee bricks, boxes and banks can be established across a site, depending on the scale of the development. 

Bee bricks should be considered at the design stage and incorporated during construction.   Bee boxes can be installed at any stage and placed on a range of structures, but require regular inspection for maintenance and potential replacement.  Both require placing around 1 meter above the ground where the entrance will be unobstructed, in an open unshaded area with a south or south-east facing aspect.

Bee banks are simple to construct and require no specialist skills.  They can be incorporated in to site landscape works, requiring ground space (the smallest mounds being around 2 x 2 meters), exposed to direct sunlight for at least half of the day, and the capacity to manage vegetation and maintain bare ground.

Future Management 

On handover of the development to the owner / factor, the location, purpose and maintenance of these features should be clearly documented.

Bee bricks and bee boxes require vegetation in front of them to be managed to ensure entrances are not covered or shaded. Bee boxes are more vulnerable to damage and water ingress over time and require regular inspection, with repairs and replacements undertaken only when unoccupied (remembering that during winter the next generation of bees will still be developing in occupied tubes).

Bee banks require regular but low level management.  Areas of bare ground must be kept vegetation free, and areas with wildflowers should be cut twice a year in line with normal wildflower meadow management practice.  For some ground nesting bees it is important to leave clumps of grass and tufty edges un-mown for the bees to use. 

Complementary Measures

Bee bricks and boxes can be incorporated into several other features, including bug hotels (measure 11), green walls and screens (measure 6), wildlife walls (measure 16), the living roofs and walls of utility green roofed structures (measure 5) and wildlife towers (measure 14).  Bee banks can have a hibernacula (measure 9) built under the mound, and the top of the mound seeded with a wildflower meadow mix (measure 2).

It is essential that there is adequate pollinator resource available for bees, with consideration given to use of pollinator plants (measure 1), wildflower meadows (measure 2) and hedgerows (measure 7).  Solitary bee species are some of the best pollinators of fruit crops, and incorporating these features into orchards (measure 3) provides important food source for the bees.

Nature Notes

The solitary bee species supported by these features nest singularly and not in colonies. This is similar for wasp species which may utilise the nests, as well as parasitoid wasp species which attack the nesting species to lay their eggs within them.  Many of these species do not sting, or those that might are less aggressive than social species protecting a large well-resourced nest.  Instead they will often move to a new nest hole rather than risk injury in defence.

As the species nest singularly they do not pose a risk of the nests expanding outside of the confines of the measure into the wider structure.

Further Information

• On using bee bricks see the Falmouth University guidance
• On creating a bee hotel see the RSPB’s Build a Bee Hotel, NatureScot’s Promoting pollination with bee houses, and Buglife’s Establishing a bee hotel
• On creating a bee bank see Buglife’s How to create a Bee Bank

These features provide shelter for a range of species including invertebrates and mammals.

Bug Hotel

Wooden frames or pallets are securely stacked on top of each other and their voids filled with a variety of materials.  The base is usually packed with leaves and logs to support damp loving species, and higher levels packed with wood, straw filled plant pots and similar items to create crevices and gaps for insects to live in.  This can include bee bricks and boxes, and wood blocks or logs with drilled holes (measure 10).  The hotels can be roofed to reduce damp in upper levels and enhance their attraction for insects like solitary bees.  The lower levels especially can also be set up to attract small mammals and amphibians.

Bug Box

Coming in a variety of shapes and sizes, wooden bug boxes appear similar to a bird box with the front missing.  The box is stuffed with twigs, wood blocks and similar to provide a range of cracks and crevices for insects.  Boxes can be mounted individually or in groups on suitable features, providing a habitat similar to part of a bug hotel.

Benefits to Nature

These features provide essential shelter and living habitat for a wide range of species.  This includes space for some invertebrates to hibernate, pupate and establish nests. Small mammals and amphibians can also use bug hotels for shelter, and the residents of both hotels and boxes provide a food source for these and bird species.  Other benefits include nutrient recycling, pollination and pest control.

Key Requirements

A number of bug hotels and boxes can be easily established across a site depending on the scale of the development. No specialist skills are required for their construction or maintenance, which can utilise pallets, off cuts and other unwanted material from the construction process.  To avoid potential pests and diseases building up in the hotels and boxes, they should be constructed to allow the elements to clear them out naturally on occasion.

Bug hotels require a ‘pallet sized’ patch of shaded ground, although if looking to encourage solitary bees and sun loving species the upper levels should be in sun light for at least part of the day.  Bug boxes can be included on the smallest of sites and mounted on almost any feature with full or partial shade.  Unlike bee boxes (measure 10), most invertebrates utilising these will require some shade and moisture.

Future Management

Bug hotels and boxes should be inspected annually and where replacement is required this should take place outside of the hibernation period and small mammal main breeding period.  Bug hotels can require leaf litter and rotted logs to be topped up (avoiding the use of any potentially invasive plant material), and the structural pallets will eventually require replacing.  Bug boxes should be checked regularly to ensure they are still securely fixed in their position.

Upon handover of development from developer to the owner / factor, the location, purpose and maintenance of these features should be clearly documented.

Complementary Measures

Bee bricks can be included in bug hotels and bug boxes can incorporate similar elements to bee boxes for solitary bees (measure 10).

Both bug hotels and boxes can be placed in various habitats, including woodland and scrub (measure 4) and along hedgerows (measure 7), to provide additional niches within these habitats (especially within urban areas).  Within orchards (measure 3) they can sustain invertebrate predators to help naturally suppress damaging pest species.  Bug hotels with a cavity in the base large enough for a hedgehog can be placed on a hedgehog highways (measure 12).

Swales and ditches, biodiverse SuDS and ponds (measures 20, 21 and 22) can have bug hotels placed close by but away from the risk of flooding, providing shelter especially during dry periods and for over wintering of the semiaquatic species.  If there are suitable structures, bug boxes can be mounted.

Wildlife walls, wildlife towers and green walls / screens (measures 16, 17 and 6) can have bug boxes fixed to them.  Living roofs (measure 5) can have bug hotels and boxes where their weight can be supported and securely fixed.

Nature Notes

Encouraging bugs in the garden and landscaped areas is unlikely to result in them becoming ‘pests’, as bug hotels and boxes also help boost their predators (invertebrate, small mammal and amphibian species).  Their damp environment can provide a refuge over winter not only for bugs but also their predators.  These features can therefore help restore a more functional ecosystem, especially in new habitats.

Further Information

• On creating a bug hotel see the guidance by the RSPB and Buglife, and The Wildlife Trusts’ How to build a bug mansion
• On creating a bug box see the Scottish Wildlife Trust’s Build an insect hotel

Hedgehog highways and houses are complementary features providing safe shelter, movement and foraging opportunities.

Hedgehog Highway

Hedgehog Highways enable free movement in and around new development to access suitable foraging habitat and discourage access to areas that pose risks (such as road crossings, industrial areas and water features).  It involves: 

• improving permeability of fences and walls by including a 13cm by 13cm gap at their base
• improving connectivity of existing and new habitats both on site and with surrounding habitat, to create corridors enabling movement
• promoting the management of gardens to encourage hedgehog foraging
• reducing dangers to hedgehogs by providing escape routes from ponds and ditches and removing obstacles that may trap them 

Hedgehog Houses

Hedgehog houses provide shelter for hedgehogs during the day, and space for raising young and for hibernation. They comprise a large wooden box with a roof and a long corridor like entrance that can be sited within scrub, under bushes or a hedgerow, in a leaf pile or in a log pile.

Benefits to Nature

The primary focus is supporting hedgehogs, whose numbers have declined rapidly despite the otherwise suitability of many urban gardens.  But many other amphibians and mammals species can also benefit from gaps in fences and walls enabling movement, and the shelter provided by boxes.  Planted corridors and foraging habitat will benefit a broad range of species, especially once it has matured.  Other benefits include pest control.

Key Requirements

The larger the development the greater the extent of these features should be expected.  Most development with undeveloped grounds will be able to include some, if not all, of these features.  A small development with a garden can include hedgehog houses and gaps in boundaries to allow movement between the garden and surrounding habitat.  Larger developments can plan to create highways with planting and boundary gaps to connect foraging habitat within the site and with surrounding habitat.  Developments with open space can also include foraging and habitat corridors to enhance connectivity.

Hedgehog houses are simple and cheap to construct (or can be purchased).  They need to be placed amongst shrubs or other cover that provides shelter, in an area accessible to hedgehogs and not encouraging movement near to roads or other hazards.

Future Management

For hedgehog highways to retain connectivity, property owners and site managers will need to be aware of the purpose of gaps in walls and fences, and regular but minimal maintenance undertaken.  This includes regularly checking routes for litter and dumped material, and gaps in walls and fences, to ensure they have not become blocked.  Fences discouraging access for hedgehog safety need to be maintained and any gaps closed, and areas of habitat created for foraging and connectivity managed appropriately.

Hedgehog houses require occasional inspection for maintenance and eventual replacement (avoiding the main breeding and hibernation seasons).

Complementary Measures

Hedgehog highways can incorporate hedgerows (measure 7), woodland (measure 4) and meadows (measure 2) to connect hedgehog habitat and provide foraging areas.  Swales (measure 20) can create a corridor through open ground, and log piles and hibernacula (measures 8 and 9) can enhance foraging.

Hedgehog houses can be placed within a number of other measures that provide additional shelter. This includes log and leaf piles (measure 8), the base of bug hotels (measure 11), hedgerows (measure 7), woodland and shrub (measure 4) and orchards (measure 3).  Hedgerows often provide key routes for movement of hedgehogs, and in orchards they can be important in controlling some pest species.

Nature Notes

Hedgehogs are one of our fastest declining mammal species in the UK.  They are vulnerable to road collisions and can become trapped in narrow spaces, trenches and ponds.  Hedgehogs can struggle to negotiate even low obstacles and can seek to avoid them, extending travel routes and potentially putting them in to more danger.

Hedgehogs are a natural predator of many garden ‘pests’ (such as slugs and snails), and can play an important role in biological control.

Further Information

• On creating corridors for movement see the British Hedgehog Preservation Society and People’s Trust for Endangered Species Hedgehogs and development guidance, the RSPB’s guidance on Creating nature highways and byways, and The Wildlife Trusts’ How to create a hedgehog hole guidance
• On constructing a hedgehog house see the British Hedgehog Preservation Society and People’s Trust for Endangered Species’ Give a ‘hog a home guidance, RSPB’s Build a hedgehog house or The Wildlife Trusts How to build a hedgehog home
• On creating natural homes for hedgehogs see the British Hedgehog Preservation Society’s Hedgehog-friendly garden features
• For general advice and information see the British Hedgehog Preservation Society and People’s Trust for Endangered Species’ Hedgehog ecology and land management and Your A-Z of helping hedgehogs

Nests and nest boxes can be fixed to buildings, structures and trees, or incorporated in the wall of the building itself.  Different species of bird nest in different sized and shaped boxes. 

General Nest Box

The standard nest box, commonly constructed from wood, is suitable for multiple bird species dependent on the diameter of the nesting hole, or alternatively providing an open front rather than a hole as an entrance.  For some species the standard box is larger (such as for starlings), or placed in groups to encourage breeding success (such as for sparrows).

Swift Brick and Box

A swift brick is a long rectangular hollow brick that replaces a standard brick in the wall under the eaves.  The brick has a ‘letter box’ like slit for swifts to enter, and separate access for maintenance.  A swift box is a wooden box of similar specification to the brick, but is fixed to the outside of the structure.

Swallow and House Martin Nests

Swallows and house martins use similar bowl shaped nests, with an open top for swallows or a side entrance for house martins.  Made from plaster or concrete to reflect natural mud and grass nests, they are affixed under the eaves of a structure.

Benefits to Nature

These offer immediate nesting opportunities for a range of bird species, providing new niches that can support the species wider dispersal.  General nest boxes can support a wide range of cavity nesting species of conservation interest, with careful sizing of the entrance hole or open front allowing for targeting of specific species.  These are more likely to be successful if the targeted bird species are already present in the vicinity.

Swifts are in rapid decline and where conditions are suitable new nesting areas can help. The boxes are often utilised by house sparrows and starlings which are also of high conservation priority. House martin nests can also be used by other species like house sparrow, but swallow nests are likely to be used by swallows only.

Key Requirements

All types of bird box are available to buy or can be easily built (possibly with materials left over from construction).  The larger the development the more boxes would be expected to be installed, and of a greater variety.  To be successful there will need to be adequate foraging habitat available for the species provided for.

General nest boxes require a structure or tree of reasonable size to be securely mounted on, with a north east to north west aspect to avoid overheating from direct sunlight.  They require some shelter from the prevailing weather and an unimpeded flight entrance.  They should be placed at least 2 meters off the ground and avoiding access from predators (like cats), but allow access for maintenance and cleaning out.  House martin and swallow boxes require similar checks, but mounted under eaves or similar structure to provide shelter.

Swift bricks and boxes need to be sited at least two stories off the ground, with a wide open area in front to allow easy passage for their residents.  A north east to north west aspect is preferred but overheating is less of an issue in Scotland and shaded south facing aspects are feasible. 

Future Management

General nest boxes will need checking and cleaning annually (between October and January), to remove nests from the past year and any abandoned wasp or tree bumble bee nests.  Any signs of damage or decay will need repairing or boxes replaced, and the mounting point to trees or structures checked to ensure it is secure and will remain so for the year ahead.

Swift bricks and boxes need annual cleaning, particularly if used by house sparrows and starlings that can bring in bits of plastic waste as nesting material, which swifts are especially likely to get trapped in.  The mounting point of boxes require checking annually, and any decay repaired. 

House martin and swallow nests don’t usually need annual cleaning.  They should still be inspected yearly in case other bird species have dragged in plastic waste or other debris that could trap swallows or martins, and the bowl and mounting on the building checked for decay.

Complementary Measures

General nest boxes can be incorporated into many other measures, including orchards (measure 3) and scrub and woodland (measure 4) when the trees are mature enough to support their weight.  They can also be placed within hedgerows (measure 7), providing additional shelter for more open boxes (the species that use these often being associated with hedgerows). 

All of the boxes and nests can be placed on wildlife towers (measure 17) and incorporated into green walls and screens (measure 6), where the site and habitat are appropriate for the type of box.  Similarly for living roofs (measure 5), where there are appropriate mounting points on the roof or its sides, although open fronted nest box may need more shelter.

Nature Notes

Birds can be fussy when choosing whether a nest box is suitable to nest in or not, and this is difficult to predict so placing as many boxes as possible can help.  The more types of bird box placed in a development, the more species that will be supported.  Most bird species which utilise nest boxes feed on a large number of invertebrates (especially when feeding chicks), and therefore play an important role in ’pest’ control.  Access to suitable foraging habitat is therefore essential.

Further Information

• On making general nest boxes with a hole or open fronted see the RSPB’s Making and placing a bird box and Scottish Wildlife Trust’s Build a nest box for birds
• For a range of advice on swift bricks and boxes see the Tayside Biodiversity Partnership Swifts page, and the RSPB’s Create a high home for swifts
• On encouraging swallows see the RSPB’s Attracting swallows to nest
• On making a house martin nest see the RSPB’s How to attract house martins

Owl boxes are sizable bird boxes, much larger than those for other bird species.

A barn owl box often has a pitched roof with an entrance hole at its peak and landing platform on the outside. The box is very large, with a floor area as much as 1 m², 50 cm deep and a 13 cm square entrance.  Tawny owl boxes are rectangular boxes nearly a metre in length, with at least a 20 cm square entrance.

Benefits to Nature

Owls require large cavities to nest within, which only occur naturally in trees of considerable age. Owls, especially barn owls, have benefited from barns in the past but many of these structures are being lost to development.  Barn conversions, modifications and modern structures often no longer offer suitable nesting spaces.

Owl boxes provide nesting and roosting opportunities, primarily for barn and tawny owls.  Tawny owls are more likely to use boxes in urban or peri-urban areas.  Other cavity nesting birds (for example jackdaws) can also use these boxes, and other birds of prey (for example kestrels) may use barn owl boxes on trees.

Key Requirements

Barn owl boxes can be mounted inside a roof structure, or on the outside of a suitable building under the eaves.  They do not like large amounts of human activity, therefore installation on dwelling structures should be avoided.  However barn conversions, agricultural and abandoned buildings can be suitable if disturbance can be minimised. 

Where there is no suitable building or structure, barn owl boxes can be tree mounted. However their size requires a large mature tree for support.  Where suitable trees are lacking a large wooden pole can be erected for a box to be mounted at the top.  The pole needs to be stable and well secured, sited where possible near trees or at least in a sheltered position (especially from high winds and bad weather).

Tawny owl boxes are mounted under a sturdy branch on a mature tree to replicate the crevices in trees that provide natural nest sites.  Trees must be strong enough to support and shelter the box.  Tawny owls are more susceptible to disturbance than barn owls and this should be considered in siting.

For any of these features to be successful there must be suitable habitat nearby.  Rough grassland habitats supporting small mammal populations are important sources of prey, as well as woodland, hedgerows, hibernacula (a space suitable for hibernation) and log piles.

Future Management

Boxes require cleaning before every nesting season even if owls have not occupied them as other species may have nested.  Care must be taken to ensure that there is not a roosting bird within, even outside of the breeding season.  The flight path and entrance into the box should remain clear, and the mounting points of boxes checked yearly to ensure they remain secure and not at risk of falling (especially in bad weather).  Barn owls have additional legal protection from disturbance. 

Site maintenance plans must have the boxes marked on them and all maintenance, ground and operations staff should be aware of their positions to ensure works or general ground and building maintenance does not disturb or cause any impact on the boxes.  Foraging and shelter habitat requires maintaining to encourage suitable prey densities.

Boxes mounted in buildings require regular inspection to ensure access remains clear, especially where there is a risk of entrances becoming blocked by stored materials.  Where buildings remain in use, care must be taken to avoid disturbance especially during the breeding season and users aware of box location.  Where mounted on unused structures these should be regularly inspected to ensure they remain secure for both the owls and person maintaining the box.

Tree and pole mounted boxes require annual inspections to check they are secure and stable, and the tree, branch or pole on which they are mounted are in good health.  Trees providing shelter for pole mounted boxes should be checked as remaining in place.

Complementary Measures

To complement nest boxes provide meadows (measure 2) for owls to forage within, and measures supporting small mammal prey (mice and voles are the main basis of their diet).  These include log and leaf piles (measure 8), hibernacula (measure 9), wildlife swales and ditches (measure 20), rivers and burns (measure 23) and wildlife walls (measure 16) which can also provide a perch to hunt from for Tawny owls.

Hedgerows (measure 7) provide corridors for owls to move along as well as for their prey, with taller emergent trees providing hunting perches.  Woodland and scrub (measure 4) will provide shelter and day roosting for owls and also their prey, with tawny owls using trees along the woodland edge as a hunting perch.

A wildlife tower can also provide nesting space, especially for barn owls (measure 17).

Nature Notes

Barn owls are a protected species and cannot be disturbed, especially when breeding. The repair and cleaning of boxes should be done in winter and only if the box is not used as a winter roost.  Other works may require a licenced ecologist.

Barn owls eat a large number of small mammals and can contribute significantly to pest control.  Where barn owls are present or being encouraged the use of poisons for rodent control should be avoided as through the food chain these chemicals can accumulate in barn owls to their detriment.

Further Information

• The Barn Owl Trust provides advice on Where’s the best place for your Barn Owl nestbox?, and guidance on Barn owl nest boxes for inside buildings, Barn owl boxes for trees, and Pole mounted nest box for barn owls
• The Barn Owl Trust provides designs for other owl box types, including Tawny owl nestboxes

Different species of bat require access to different types of roost site.  Bat boxes and access tiles / slates and bricks can provide these when incorporated in to a building or added to a structure or tree.

Internal bat boxes

Bat boxes come in a range of different forms for incorporating in the walls and structure of buildings.  Larger bat boxes can be built in to a roof void or a cavity wall.  These boxes have a sheltered entrance slit to allow entry, with the bats being contained within the box and do not enter the structure itself. 

External bat boxes

External bat boxes can be placed on buildings, structures or trees, or a specifically designed bat box can be mounted on top of a pole. The most common type of box is similar to a wooden bird box but with the front panel sloping in towards a longer back panel that includes a landing area at the bottom, with a narrow gap at the box’s base for entry.  Assembled wooden and concrete cast boxes can be purchased, as well as larger maternity and heated boxes.

Bat access tile / slate and bricks

Hollow bat bricks and roof tiles / slates are incorporated in the wall and roof covering of buildings and structures.  These do not themselves constrain bats, allowing access to the roof space or other voids in the structure that are reachable from the entry point. 

Benefits to Nature

Bats require suitable cavities for shelter, providing day roosts, maternity roosts and for overwintering.  Some species will use small cavities and under roofing material, while others prefer a much larger roof void.  These can be found within older large trees, buildings and structures, but many have been lost to development or following a building’s conversion.  New structures rarely provide suitable spaces.  A broad range of bat species can benefit when a number of boxes, bricks and tiles / slates of different sizes and type are used.

Key Requirements

Bat boxes, tiles / slates and bricks are available to buy, and external boxes are simple to construct, possibly with materials left over from construction.  The larger the development the more boxes and greater variety would be expected to be installed, and should reflect that different species of bats have different requirements.

Bat boxes must be placed at least 3 meters above the ground, with an open route to its entrance and avoiding overhangs or perches where predators could mount easy attacks. Pole mounted boxes should be close to a woodland or hedge and away from areas likely to be disturbed, with open space around them.  Boxes can be orientated in any direction, although a south facing box in direct sunlight will be least suitable.  Installing several in different positions with varying temperatures will provide a wider range of suitable roost options.

Bat tiles / slates and bricks should only be used where the roost space will not come in to conflict with other uses (such as storage of potentially harmful materials), and avoid potential human disturbance by utilising used voids.  Any openings in to other parts of the building should be closed off.

Accessible foraging habitats such as woodland, scrub, grassland, wetlands and water features, and hedgerow and tree corridors providing safe transit routes, should be in the local area.

Future Management

Bat boxes require minimal management, external wooden boxes requiring most maintenance.  If any repair, replacement or maintenance work requires opening or disturbing a box this must be done by a licenced bat worker.  Bat boxes should be marked on all landscape plans and maintenance staff made aware so that they are not disturbed during any works undertaken.

Internal bat boxes which are heated should be checked in line with manufacturer’s instructions to make sure they are functional.  Periodic removal of droppings is likely to be required and needs to be done by a licensed bat worker.  External bat boxes mounted on trees or buildings should be visually inspected at a distance to make sure they are still secure and functional.

Complementary Measures

External bat boxes can be fixed to trees able to support them in orchards (measure 3), emergent trees in hedgerows (measure 7) and scrub and woodland (measure 4).  Where trees are young, pole mounted boxes can be used, or their future placement recognised in the management plan.

Dependent on the design and suitable fixing points either internal and / or external bat boxes can be included in wildlife towers (measure 17), living roofs (measure 5), green walls and screens (measure 6).  These also provide foraging habitat, and act as ‘stepping stones’ in support of movement across developed habitats.  Hedgerows (measure 7) also provide important foraging and commuting routes.

Various measures can provide bat foraging habitat, including plants for pollinators (measure 1), wildflower meadows (measure 2), orchards (measure 3), woodland and scrub (measure 4) and ponds and biodiverse SuDs ponds (measures 21 and 22). Where lighting is essential, bat friendly lighting (measure 18) should be used near boxes and travel routes.

Nature Notes

All bats are protected by law and subject to certain safeguards to ensure they are not disturbed.  Any disturbance of bats or damage to roosts must be licenced and undertaken by a qualified licenced ecologist.

Further Information

• On the construction and siting of all types of bat boxes see the Bat Conservation Trust’s Bat boxes guidance
• On enhancing habitat for bats see The Fresh Water Habitats Trust Creating ponds for bats, The Wildlife Trusts’ How to attract moths and bats to your garden, and Hedgelink’s How to manage your hedge for bats
• On landscape and urban design and designing for biodiversity see the Bat Conservation Trust’s Guidance for professionals

A wildlife wall is a dry stone wall containing a large number of gaps, crevices and internal voids within it to allow a range of invertebrate, small mammal and amphibian species to shelter and hibernate.

Benefits to Nature

Drystone walls have been disappearing from our landscape, resulting in the loss of shelter for amphibians, reptiles and invertebrates, and nesting space for birds and small mammals.  Its surfaces also provide amphibians and reptile basking sites, and the stone itself will be colonised by a range of lichen and moss species which provide a food source for other invertebrates.

Key Requirements

A wildlife wall can be included in any size of development, either as a freestanding structure or demarcating a boundary.  Even a small length of wall can create an important habitat feature, although it should not replace or be preferred to keeping or creating a native hedgerow.  Wildlife walls should be marked on ground management plans to ensure future management retains their function (to ensure their voids and crevices are not filled in during maintenance).

Future Management

If walls are constructed well, minimal future management is required.  Regular inspection should check that the wall remains sound and any lose rocks posing a risk of falling are secured.  Gaps, cracks and crevices provided for wildlife should be checked to ensure they have not been filled in or otherwise lost through maintenance.

Complementary Measures

Solitary bee boxes (measure 10) and bug boxes (measure 11) can be mounted upon wildlife walls. A wildlife wall can also have spaces left in it for wildlife and pollinator friendly plants to be planted into the wall, or similar climbing plants grown up it (measure 1).

Nature Notes

There is sometimes concern that these structures need to be in a poor state of repair if they are to provide the crevices that support wildlife.  However a stable and safe wildlife wall can be created either with or without mortar securing its stones, with suitable gaps left for wildlife.

Further Information

• On creating a wildlife wall see The Wildlife Trusts’ How to build a mini stone wall

A wildlife tower is a small structure resembling a tower that has bat roosting and barn owl nest spaces built into it.  Other bird boxes and bug boxes can be added to support additional species.

Benefits to Nature

Many older rural structures can provide suitable roost and nesting sites that can be lost during restoration and rarely found in modern structures.  The species benefitting will depend on the features within the tower. Most will include a nesting space for barn owls and bat roosting boxes, which may be used by other cavity nesting species.  On the outside nest and bug boxes can support a variety of bird species and insects.

Key Requirements

A development needs to include grounds for siting the tower, with suitable foraging habitat such as hedgerows, grasslands, wetlands and water features found nearby, ideally linked by connecting habitat.  The species supported require limited disturbance so cannot be near dwellings or well used areas.  The tower should have some shelter from direct sun light or the elements.

Future Management

The structure should be checked annually to make sure it is secure and in good condition with foraging habitat supporting its species maintained to a high quality.  The internal barn owl spaces within the tower will need to be cleaned out once a year before breeding season commences, making sure not to disturb any owls that may be roosting in the tower during the day.

Any features like bird boxes affixed to the outside should be maintained as described in measure 9.  If bat roosts are built into the tower any repair, replacement or maintenance work must be done by a licenced bat worker.

Complementary Measures

A wildlife tower is usually created with a roost for barn owls, but if this is not the case an owl box (measure 14) can be placed in or on to the structure.  Multiple bird boxes (measure 13) and internal or external bat boxes (measure 15) can be placed on the tower, along with bee boxes (measure 10) and bug boxes (measure 11).  A living roof, green wall or screen (measures 5 and 6) can also be incorporated.

Nature Notes

Both barn owls and bats, the target species for a wildlife tower, are scheduled protected species subject to certain safeguards.  Assistance in designing, placing and maintenance from a licenced ecologist may be needed. Undertaking maintenance when these species may have taken up residence and therefore could be disturbed, will require a licenced ecologist.  Some local wildlife and NGO groups may have members with the appropriate skills and licences that could assist.

Further Information

On constructing a wildlife tower see the Barn Owl Trust’s How to build a wildlife tower

Some of the biodiversity measures enhancing wildlife will themselves benefit from additional measures to safeguard the animals supported.

Well planned wildlife friendly lighting will minimise its use and seek to avoid lighting natural habitats (especially woodland, grassland, ponds and bat foraging territories), with light shields or buffer zones of bushes, hedges and green screens used to keep light from these sensitive environments.  Lighting duration can also be limited to necessary times (through use of sensors and timers), and LED bulbs specified that utilise light wavelengths that are less disruptive to wildlife (especially bats) and less attractive to night time invertebrates.

Benefits to Nature

Artificial lighting, whether from outdoor lights or cast from lights within buildings, can negatively impact a large number of species either through attracting species or displacing natural movement to their detriment.  Nocturnal mammals and bats in particular are known to be affected by artificial light that disrupts movement and foraging behaviour.  Ongoing research on nocturnal insects such as moths has shown artificial lighting, including modern LED lights are affecting foraging behaviour and predation of a number of different invertebrate groups. 

Key Requirements

The consideration of wildlife friendly lighting is appropriate for most development, but particularly those larger developments incorporating external lights.  Where lighting is necessary, lights should be shielded away from important habitat areas.  This requires assessing lighting from both external and internal light sources, and modelling the fall of lighting on to any areas supporting biodiversity.

Plan the placement of screens, barriers, light shields and LED lights with wildlife friendly wave lengths, and consider the placement of lights in buildings and fittings and shades that will lesson light cast out of windows. Sensors to dim or switch off external and internal lights when not necessary can be considered where security concerns allow.

A plan with a clear statement recording the lighting actions taken is required so that future site managers can maintain and keep these features in place, and consider mitigating any changed or new lighting in the future.  An overall site plan showing areas that are badly effected by light should identify future priorities for mitigation.

Future Management

Lighting must be regularly inspected along with the mitigation measures to ensure that light pollution is minimised and that lights are functional with repairs carried out promptly.  Where vegetation is used to screen areas from artificial light this needs to be maintained to remain effective, and dead or diseased vegetation replaced.  The details of the lighting plan and principles to be followed must be kept up to date, the installed system maintained to manufacturer’s specifications, and owner or site factor aware of these requirements.

Complementary Measures 

Wildlife friendly lighting can complement most of the measures benefiting wildlife, but will be particularly important where some vulnerable species such as bats are found.  This includes wildlife ditches and swales (measure 20), biodiverse SuDs ponds (measure 21), ponds for wildlife (measure 22) and rivers and burns (measure 23).  These are prime foraging areas for bats, particularly species like Daubenton's bat that rely heavily on feeding on semiaquatic insects.

Log piles (measure 8), hibernacula (measure 9), hedgehog homes (measure 12), bird, owl and bat boxes (measures 13 to 15) and wildlife towers (measure 17) should be shielded from artificial light as this can reduce the likelihood of their use and disrupt movement, foraging, hunting ability and behaviour of their prey.

Orchards (measure 3), hedgerows (measure 7), wildflower meadows (measure 2) and woodland and scrub (measure 4) can support many nocturnal invertebrates and their nocturnal predators, and are all sensitive to artificial light.  Pollinator friendly plants (measure 1) and living roofs seeking to encourage pollinators (measure 5) can all benefit from wildlife friendly lighting to encourage nocturnal pollinators.  Green screens and walls (measure 6) can be used to create screens to block artificial light and protect more sensitive habitats.

Nature Notes

Our understanding of the effects of artificial light on a wide range of species is still growing, with research on invertebrates showing serious impacts on populations in illuminated areas.  The significance of impacts is still to be fully understood, but it is important to ensure the enhancements achieved by other measures are not undone through poorly designed lighting.  Where biodiversity interests are already present, artificial lighting used during the construction phase should also adhere to the same wildlife friendly principles.

Further Information

• On considering and mitigating the effects of artificial lighting see the Bat Conservation Trust’s website and Buglife’s advice on light pollution.

These features channel rain water for the purpose of water control but are designed and managed in a way to provide for wildlife.

Rain and Bog Gardens for Buildings

Rain gardens consist of planters and low lying garden areas, planted with wet loving or tolerant plants that temporarily retain water for slow release into the surrounding area.  The bog garden is similar, lined to increase water retention if necessary, and planted with water loving wetland species.  Rain water is channelled from a swale, down pipe or water butt overflow to the rain or bog garden, to increase attenuation by slowing runoff and reduce potential flood risk.

Rain Gardens for Streets

Street rain gardens incorporate swales and road kerbs to channel runoff from roads, parking areas and paths.  Designed to absorb larger volumes of water they are usually planted with trees and shrubs for greater take up of water, that are more tolerant of pollutants.  Some include deep hidden wells dug along the street edge with a tree planted on top.

Benefits to Nature

The damp or wet habitat areas created support many invertebrate and amphibian species.  These areas can be especially beneficial to pollinators as the availability of water in dry weather can help increase nectar production.  With their enhanced water storage capacity the plants and trees planted in the rain garden can remain healthier, providing more shelter and a better food source for invertebrates.

Other benefits include water control and improving water quality by encouraging pollutant filtration, and promoting cooling.

Key Requirements

Rain and bog gardens can be relatively small areas, incorporated in to any scale of development as long as any excess water can be safely diverted away.  The area needs to be of a gradient that allows water to sit or slowly pass through and not run off immediately (a Bog Garden requires a dip in the landscape), with soil not so free draining to allow some accumulation of water.  A bog garden may require a liner if the ground is very permeable.

Rain gardens for streets can be accommodated in developments with a paved street or communal area from where water can be channelled.  Careful consideration of the volume of water that the landscaped area can absorb is required, with a suitable overflow into further features in case the volume of water exceeds its capacity. 

Future Management

Regular but low level maintenance is required to ensure the feature and vegetation within in it are functioning correctly.

• Ensure water can flow freely in to the rain garden and also from the outflow, without eroding the soil.  Debris can be easily washed in and should be regularly ‘litter’ picked. 
• Trees and plants within the rain garden require checking to ensure the wet conditions are suitable, and regular weeding to prevent any invasives becoming established or other species dominating.

Complementary Measures

Rain gardens can be planted with a range of suitable wildlife and pollinator friendly plants (measure 1). Wildlife swales and ditches (measure 20) can be used to channel water into a rain garden, and provide for its overflow, and can link to SuDS ponds (measure 21). 

Bug hotels and log and leaf piles (measures 11 and 8) can be placed in rain gardens, providing a damper environment that is particularly beneficial to invertebrates and amphibians in dry weather.

Nature Notes

By retaining water these features reduce the risk of flooding both on site and downstream of the development.  These areas will remain damper for longer periods than the surrounding area which can be important for invertebrate species, especially amphibians during periods of exceptional dry weather.  As with all vegetated areas they contribute to urban cooling.

Further Information

• On creating a rain garden see the Rain garden guide, Green Action Trust’s 10,000 raingardens for Scotland campaign and The Royal Horticultural Society website
• On creating a bog garden see The Wildlife Trusts’ How to make a bog garden

These features channel water for the purpose of water control but are designed and managed in a way to provide for wildlife.  They are strongly preferred over grey infrastructure such as buried pipes for their wider benefits.

Swale or Rill

In gardens this is a shallow ditch of around 30cm depth and 60 cm width, that channels water from a water butt, patio or similar towards a pond, bog garden or rain garden. The excavated earth is usually mounded on one side.  Swales are wet intermittently, but deeper and flatter sections can be included to create more varied conditions.  The swale and adjacent earth mound can be seeded with wildflowers such as a wetland meadow mix.  These features can be created on a larger scale in areas of public greenspace, or placed as a feature for wildlife on its own even if there is no need to channel water.

Wildlife Ditch

Wildlife ditches can be created new (with soil mounded to one side), or existing ditches modified to increase diversity by reducing the slope angle of their banks, profiling sides to create shallow benches with different water depths, and establishing pools of water.  Bare sediment as well as aquatic, emergent and wetland vegetation is encouraged along ditch edges.

Benefits to Nature

These features benefit a large range of aquatic and terrestrial flora and fauna, providing a source of food and water and facilitating species movement.  Their linear nature can help semiaquatic insects especially to move through the landscape.  When dry they act as wildlife corridors, especially through open areas. They remain cooler and damper than surrounding land, providing shelter in dry weather for amphibians and invertebrates especially.  Damper areas and permanently water filled edges provide habitat for a range of aquatic fauna and flora.

Other benefits include water control and improving water quality by encouraging pollutant filtration.

Key Requirements

Both ditches and swales need to be planned to avoid facilitating the movement of contaminated water or pollutants to different parts of the site or to water courses, and increasing the risk of flooding.

Swales can be installed in medium and larger sized gardens and areas of greenspace, often as part of a sustainable drainage system (such as connecting to a rain garden).  Small swales can be easily dug by hand, larger ones requiring machinery.

Ditches can require more planning to ensure profiling to encourage water retention does not cause local flooding, and they continue to provide necessary drainage.

Future Management

Ditches and swales require annual management.  Sown wildflowers should be cut once a year, with cuttings removed from the swale and avoiding cut material falling in the ditch.  Any hedgerows over shadowing the ditch should also be trimmed back and their material removed.

As ditches vegetate and collect silt, these and any blockages should be removed in late summer (avoiding the main breeding time) to maintain water management.  This should be done in sections over time, leaving undisturbed parts to allow wildlife to recolonise cleared areas (cleared material should be left beside the ditch to allow animals within to return).  Ditches can be vulnerable to invasive plant species, whose management and control may require ecological expertise.

Complementary Measures

Swales can channel water into rain gardens (measure 19), connect habitats as part of a hedgehog highway (measure 12), and be sown as a wildflower meadow (measure 2).

Log and leaf piles (measure 8), hibernacula (measure 9) and bug hotels and boxes (measure 11) will provide damp places for semiaquatic species including amphibians to shelter during dry weather and to over-winter in.  Wildlife ditches can run beside hedgerows (measure 7), that will provide additional niches to support biodiversity.

Where ditches are near suitable foraging or hibernation areas and nearby gully pot drainage systems, drain escapes should be considered (measure 24).

Nature Notes

By allowing water to be retained and the flow slowed, a wildlife ditch can help to reduce flooding downstream.  Ditches that are only wet for part of the year and go through dry spells can be a valuable type of habitat on their own right.  For many aquatic and semiaquatic insects as well as amphibians, ditches with permanent water can be key for breeding. Semiaquatic insects spend their larval stage in water and then emerge as flying adults. These insects are a key resources as prey, especially for many bird species.

Further Information

• On creating a swale see the RSPB’s Dig a damp ditch for diversity
• On managing ditches see the RSPB’s Drainage channels, Buglife’s Grazing marsh ditches – Sheet 3 Management for invertebrates, and Hedgelink’s How to manage your hedge ditches for invertebrates

Sustainable Drainage System (SuDS) ponds are designed primarily to aid water management (its quantity and quality), but can be designed and planted to enhance their wildlife and amenity value.  The pond is connected to the development’s rainwater drainage system, with either an emergency overflow or a slow release system for water to leave. They can be planted with aquatic and emergent plants and bordered with wet grassland vegetation.  The SuDS pond should not be directly connected in hydrological terms to existing wetland features if there may be water pollution issues, such as from road runoff.

Benefits to Nature

Ponds are a major feature in the landscape for biodiversity, supporting a large range of species, but their number has been steadily declining as a result of land use changes.  SuDS ponds have greater biodiversity than swales or detention basins, provide an important habitat for all Scottish amphibian species, and will also support a wide range of aquatic and semiaquatic species which are a key food source for many bird species (especially for their young). Many wildfowl including species like moorhen can also benefit from these ponds.

Other benefits include managing water flows and improving water quality by encouraging pollutant dilution and filtration, pest control and people’s health and wellbeing.

Key Requirements

SuDS ponds are most applicable for larger developments, with space to accommodate an area of emergent edge and wet grassland and of sufficient area that will retain water through a spell of dry weather.  For small developments shedding runoff to adjacent landscaped areas with a rain garden may be more appropriate.  

Any pollutants from site drainage must be at a low enough concentration to allow filtration by pond edge vegetation, with sufficient water flow to wash through pollution and nutrients.  The careful use of tall emergent vegetation around pond edges, patches of trees and scrub and the placement of boulders, can discourage people from approaching the water and improve safety, as well as reduce wildlife disturbance.  Safe viewing platforms can be provided where required.  Access for machinery to maintain the pond, vegetation and water flows will be required.

Future Management

The pond should be monitored for sediment and pollutants entering it, and action taken to reduce and remove sources if found.  High levels of nutrients entering the pond can also lead to algae blooms, and careful use of any fertilisers on site is required.   Regular checks for invasive plants is required as these can establish easily in wetland areas and invasive aquatic plants can quickly take over open water.

Both wet meadows and emergent vegetation in ponds may require cutting.  Without cutting the wet grassland can become dominated by certain species, and emergent vegetation (especially water reed) can take over open water.  Ponds can act as ‘litter traps’, requiring the area around the pond and where necessary the pond itself to be litter picked to prevent litter blowing into and building up within the pond.

Complementary Measures

Log and leaf piles (measure 8), hibernacula (measure 9) and bug hotels (measure 11) placed above the high water line can provide shelter and hibernation for many semiaquatic invertebrates and amphibians.  Leaf piles and cages will mulch down and should be placed to avoid nutrients running into the pond.  Wildlife walls (measure 16) sited near to a SuDS pond can also provide well sheltered cavities for overwintering amphibians.

Areas of hedgerow (measure 7), wildflower meadow (measure 2) and scrub and woodland areas (measure 4) all provide important foraging habitats and potentially over wintering habitats, especially for amphibian species.

Drain escapes (measure 24) and wildlife friendly lighting (measure 18) will both be important to reduce the risks to the wildlife that SuDS ponds will support.

Nature Notes

Ponds are one of the fastest declining biodiversity features in our landscape, yet they are essential for many aquatic and semiaquatic species.  Semiaquatic emerging species such as flying insects are crucial for the development of insectivorous bird chicks.  As climate change alters conditions it is essential that species are able to move to more suitable habitat, and biodiverse SuDS ponds in development can enable this by acting as stepping stones.  Attractive SuDS ponds can also benefit the health and well-being of local residents, particularly when combined with a safe viewing platform and interpretation.

Further Information

• For a range of resources, case studies and guides to creating SuDs for wildlife see the Susdrain website
• On creating, enhancing and managing SuDS for wildlife see the RSPB and WWT’s guide for local authorities and developers, Sustainable drainage systems - maximising the potential for people and wildlife
• On the use of native plants in ponds see Plantlife’s Alternative plants guide, or use the Royal Horticultural Society’s Find a plant database (to produce a filtered list of native aquatics)

Wildlife ponds come in all shapes and sizes to fit the available site, and provide an important resource for wildlife.  Where existing ponds are present their restoration and on-going management can enhance their biodiversity value.

Scrape

A scrape is a shallow pond, often found in grassland and farmland or other open habitats, that can partially dry out in the summer.  These provide important foraging habitat for waders during the breeding season and in winter if there is limited shelter for potential predators.

Mini rain pond

These can be self-contained and collect rainwater from the sky, or positioned to hold runoff from a swale or rainwater down pipe as part of a rain garden (measure 19).  They can be as small as a sink, using a container or basin sitting on or dug into the ground.  The base of the container is lined with gravel to provide substrate, with containerised water plants, aquatic and floating plants placed in the pond.  A ramp into the pond can provide access (or escape) for invertebrates and amphibians, with a log or stone pile built against the side of the container if it stands above the ground for amphibians to climb for access.

Wildlife pond

A wildlife pond provides diverse conditions to encourage a wide range of species, and can vary in size from a small garden pond to one as large as the site allows.  The pond edge allows for easy access and exit for animals (including any that fall in by accident), with shallow margins and sides that slope gradually to the deepest point.  Benches at varying depths provide a range of shallow and deeper areas, and larger ponds may include an island. 

The base of the pond includes areas of bare sediment, gravel and stones, and aquatic and emergent plants.  Native plants should be chosen to plant the pond and its surroundings, or it can be left to colonise naturally from nearby seed sources (if available).  The ground around the pond may flood intermittently, with wet grassland and riparian scrub species providing cover and foraging for amphibians.  Creating shelter and hibernacula features around the pond can provide important overwintering areas for amphibians and semiaquatic invertebrates.

Wildlife ponds in certain settings may additionally require other considerations.

• Ponds with public access should incorporate more extensive shallow margins to reduce the risk of people falling into deep water.  Where public access is of concern a combination of wet grassland, boulders or log piles and emergent vegetation can discourage people from approaching the water and improve safety.
• Ponds within an airport bird strike risk zone can reduce their attraction to large numbers of water fowl and gulls if they are kept small and shallow (perhaps a network of smaller shallow ponds), with emergent vegetation.  Extensive reed beds that can provide roosting habitat for large flocks of starling and open semi-improved grassland (which provides grazing for wildfowl) should be avoided, and sheltered areas with tree cover can discourage large wildfowl.
• Ponds in woodland require an open area of the forest or at the edge of a ride or track to allow sunlight through, with trees set back from the edge to allow space for emergent vegetation, wet grassland and riparian vegetation.  The build-up of leaf litter can be mitigated by creating bars and small hummocks on the pond bottom for plants to grow on, the deep areas in between accumulating leaf litter.
• Ponds in wetlands should avoid disrupting existing hydrology and valued habitats, and not be directly connected to ditches which can increase siltation and encroaching vegetation.  Shallow ponds can quickly be dominated by reeds, but deeper ponds with steep sides can slow or prevent this.
• Ponds on floodplains can be hotspots for plant species, but can also quickly be infilled with debris and sediment from flooding.  Creating a number of separate ponds at varying distances from the river can ensure greater availability to wildlife in this dynamic landscape.

Benefits to Nature

Ponds have been in rapid decline, but their retention and creation can provide significant biodiversity improvements even when ponds are small.  This will be enhanced where a network of new ponds fill gaps in an area with no ponds, supporting species that depend on them to move through the landscape, reducing population isolation and facilitating range expansion.  A network of unconnected but close together ponds are often particularly rich in biodiversity.

Ponds support a very large amount of biodiversity and can benefit a very large range and number of species depending on the pond’s environment.  This includes many species of wetland, semiaquatic and aquatic plants, many mammals (especially where there are populations of water voles), invertebrates and amphibians for whom they are the key habitat.

Aquatic and semiaquatic invertebrate species provide an important food source for many species including insectivorous birds when feeding chicks (which have more success in raising young when these insects are abundant).  Islands and areas with shorter vegetation are attractive to waders and waterfowl without the risk of predation.  Waders and waterfowl can be supported on scrapes and medium sized ponds or larger, while moorhens in particular can utilise even quite small ponds. 

Other benefits include managing water flows and improving water quality by encouraging pollutant dilution and filtration, pest control and people’s health and wellbeing.

Key Requirements

Where grounds are limited a mini or small garden pond can be created that will still provide an important refuge and breeding site for many species.  Greater space allows for a larger pond, or several ponds across a site, to be created.  Adequate resources for future management will be essential

There must be an adequate supply of water that can collect in the pond and replenish it. Some ponds can be seasonal and dry out at least partially, but these can still be extremely valuable to wildlife. 

Areas at risk from pollution, or activities containing pollutants that may attract wildlife from the pond to its detriment (such as settling ponds), should be avoided.  Other hazards, such as drains, require measures to avoid significant losses to amphibian populations (see measure 24).

Future Management

All ponds generally require regular management to ensure their long term continuance, with some needing additional actions dependent on their particular circumstances.  Smaller ponds may require topping up during dry weather, preferably from a water butt as chlorinated tap water can affect microbe species within the pond, and may need attention during the autumn to prevent the build-up of leaf litter.  The most common needs for larger wildlife ponds are:

• monitoring for any pollution entering the water, requiring its removal and remediation as soon as possible
• monitoring for damaging invasive non-native species, which ponds are particularly vulnerable to as aquatic plant species can be introduced via visiting waterfowl
• control of dominant vegetation, including reeds and scrub that can reduce the area of open water, decrease water oxygen levels and lead to drying out
• litter picking around the pond to prevent rubbish blowing into and accumulating in the pond with detrimental impact on biodiversity and its wider appreciation
• checking of any wildlife ramps and escapes, and for people maintaining any access and safety equipment in place.

Complementary Measures

Many semiaquatic and amphibian species as well as terrestrial animals that utilise ponds will benefit from measures providing shelter and hibernation nearby.  Areas of hedgerow (measure 7), wildflower meadow (measure 2) and scrub and woodland areas (measure 4) all provide important foraging habitats and potentially over wintering habitats, especially for amphibian species.  Log and leaf piles (measure 8 - placed to avoid nutrients running into the pond), hibernacula (measure 9), and bug hotels and boxes (measure 11) need to be above the winter high water level.  Mounting bird and bat boxes (measures 13 and 15) around ponds to feed on semiaquatic flying insects can also provide important breeding sites for these species, with wildlife friendly lighting (measure 18) if lighting is required.

The area around ponds provide important feeding areas for many mammal species, including hedgehogs which are particularly vulnerable to getting trapped in ponds, and safe access routes can be created by hedgehog highways (measure 12).  Amphibian species will move to ponds to breed and then disperse for foraging and shelter, and the risk of entrapment in road drains and gully pots can be mitigated by drain escapes (measure 24), without which populations can be significantly depleted.

Nature Notes

Ponds can be established easily, creating a valuable additional habitat that increases biodiversity in an area.   Invasive non-native plant species can be a particular risk to ponds, introduced by visiting animals (especially waterfowl) transferring seeds and other plant material caught on their feathers between ponds.  Invasive floating plants can easily be spread in this way, growing across a pond, shading out other plant species and reducing oxygen levels.  Some native species such as water reed can also be invasive, and often require management to maintain a mix of habitats.

Further Information

• On creating a mini pond see the Scottish Wildlife Trust’s Build a mini wildlife pond or The Wildlife Trusts’ How to create a mini pond
• On creating and managing a small or large wildlife pond see the Freshwater Habitats Trust’s website
• For enhancing ponds for individual species many wildlife organisations publish specific guidance, such as the Freshwater Habitats Trust and Froglife
• On the use of native plants in ponds see Plantlife’s Alternative plants guide and the Royal Horticultural Society’s Find a plant database (to produce a filtered list of native aquatics)

Development sites that include or are adjacent to a river or burn can enhance the watercourse’s biodiversity through safeguarding and restoring the natural river channel and its processes, and improve habitat condition along their banks.  Actions include:

• reconnecting and reconstructing channels, and providing space for the watercourse to temporarily flood
• placing trees and large wood material in-channel   
• applying natural flood management techniques, such as cushioning river banks from the force of the river by using living or dead tree stems, root wads, or branches
• restoring riparian habitats and establishing natural ‘buffer’ strips alongside the watercourse to reduce disturbance and bank erosion, protecting the water environment and providing a corridor for wildlife movement

Benefits to Nature

A natural watercourse provides a range of diverse and inter-connected habitats, such as fast and slow flowing water, vegetated and eroding banks, overhanging bank-side trees with exposed tree roots, tall grasses and rocky shores.  These support hundreds of different species, both in the channel and along its margins, such as invertebrates, birds, water voles, fish, waterfowl and otters.  They also provide an important corridor for wildlife movement, especially through more built-up areas, connecting up habitats within and outwith the site.

Other benefits include managing water flows and providing natural flood management, improving water quality through vegetation casting shade and encouraging pollutant dilution and filtration, and supporting people’s health and wellbeing.

Key Requirements

Understanding natural catchment and river processes, and giving space back to rivers in combination with the right river restoration techniques where required, is key.  Buffer zones of riparian scrub and wet grassland habitats of 15 to 30 metres should be included around any water features where possible, providing benefits for water quality, habitat and biodiversity.

Restoration of watercourses, involving works in the water environment, are of greater complexity and likely to require authorisation from SEPA and hydromorphological expertise to consider any flood risk.

Future Management

If implemented well, future management needs should be limited.  The watercourse should be left to its natural processes.  Control of vegetation can be done infrequently, with simple tree management techniques such as coppicing and pollarding extending the lifespan of trees and retaining their root system’s stabilisation of the bank.  Instead of felling trees to keep a watercourse clear, consider cutting back branches to just above flood level.

A watch should be kept for invasive non-native plants, for example giant hogweed, Japanese knotweed and Himalayan balsam, as these can spread readily along watercourses.  Litter can also accumulate in watercourses and should be removed to avoid dangers to wildlife.

Complementary Measures

River and burn habitats complement wet grassland (measure 2) and riparian woodland (measure 4).  Log piles and hibernacula (measures 8 and 9) can provide for over-wintering semi-aquatic species, and bird and bat boxes (measures 13 and 15) shelter for their predators.  Wildlife friendly lighting and drain escapes (measures 18 and 24) should be considered.

Nature Notes

Many of our more urban watercourses, in particular, have been degraded.  Their beds have been dredged and reinforced, obstacles to fish migration such as weirs and long culverts created, channels straightened or diverted, lined with concrete and steel and confined within high flood embankments or culverted, and banks shorn of vegetation and riparian trees removed.  New approaches and engineering techniques now seek to work with nature rather than fight against it, and can rectify this past damage.  These nature-based solutions are likely to be cheaper, require less maintenance, be more sustainable and provide a wider range of benefits than maintaining traditional engineering approaches.

Further Information

• For advice and best practice guidance on undertaking activities on or near watercourses see SEPA’s website and guidance on Sustainable riverbank protection
• For guidance and examples of river restoration see the River Restoration Centre’s Manual of river restoration techniques and IUCN River restoration and biodiversity report

Development can unwittingly introduce dangers to the wildlife that it is seeking to encourage.  Small mammals and amphibians naturally follow raised road kerbs and are in danger of falling through drain grating and into gullypots, with a significant impact on local populations of these species.  Simple measures can reduce this risk, and where they are used in connection with other measures supporting these species (beyond mitigating the development’s impact on existing wildlife), can enhance biodiversity.

Wildlife Kerbs

Wildlife kerbs can be substituted for standard British Standard kerbs next to gully pots.  They have a small recess on their front face that creates a safe pathway for animals following the vertical face of the kerb to avoid falling into drains.  Lowered sections of kerb can also be used to break up extensive lengths of otherwise unclimbable kerb in areas where amphibians will want to cross roads between ponds and wetland and good hibernating habitat like scrub and woodland.

Toad Ladders

These are small rectangular ramps, usually of metal with a textured surface to facilitate climbing, placed inside the gully pots of drains.  They enable amphibians, other small mammals and invertebrates that fall into drains to escape by climbing up the ramp’s rough surface and out through the grate. They do not impact on drainage or drain maintenance.

Benefits to Nature

Drains placed near to ponds, water features and SuDs, particularly when illuminated by nearby artificial light, can catch large numbers of amphibians and cause rapid population decline.  Frogs, toads and newts can all benefit, as well as small mammals, reptiles such as common lizard, and many invertebrates.  These will be at risk when attracted to migrate into an area of new habitat.

Other benefits include reducing the cleaning of gully pots.

Key Requirements

Wildlife kerbs and toad ladders complement each other and should be installed together.  All drains pose a risk to wildlife but priority should be given to those within 500 meters of a SuDs feature, water feature or suitable amphibian foraging or hibernation habitat (especially woodland areas). 

Appropriate kerbs should be installed during construction, but ladders can easily be retrofitted to drain gully pots.

Future Management

Wildlife and lowered kerbs require minimal maintenance.  Along with toad ladders they should be marked on site plans and the factor and maintenance staff made aware of their placement to ensure they are not removed over time.

Toad ladders can be damaged by debris washed down the drain, or become so silted up to restrict access.  Annual inspections prior to the main amphibian breeding times (in early spring), to clear debris and check mounting points remain secure, is required.  Any drains being cleaned out without ladders should be checked for trapped or dead wildlife and if found new ladders should be installed. 

Complementary Measures

These will complement other measures enhancing habitats that support amphibians, especially where preferred lines of movement will cross areas with drains.  This includes rain gardens (measure 19), swales and ditches (measure 20), SuDs and wildlife ponds (measures 21 and 22), rivers and burns (measure 23) and measures supporting hibernation (measures 8 and 9).

Nature Notes

There is limited awareness of the dangers that road drains place on wildlife, and the relatively simple solutions available.  A Perth & Kinross Council study surveyed 1500 gully pots over a three year period and found approximately 3000 trapped animals.  Some 60 to 70% of drain gully pots checked contained dead wildlife, the majority being amphibians.  Gully pots in effect act as giant pitfall traps, from which there is limited chance of escape.

Further Information

• On fixing amphibian ladders see the Amphibian and Reptile Groups of the UK’s Saving amphibians in drains
• For information on the risk of drains to amphibians and small mammals and effect of measures see the Amphibians in drains project 2014 report