Guidance - Wildcat Survey Methods
Last reviewed: 2014
Some initial considerations to help decide if a survey is required are:
- Are the proposals within the wildcat range?
- Are wildcat habitats1 likely to be affected?
1 Wildcat habitats - Studies of wildcat ecology in Scotland and elsewhere in Europe highlight the need for habitats that provide cover and that support small mammals. Wildcats tend to occupy the woodland edge or a mosaic of habitats incorporating woodland, scrub, rough grassland and moorland. They avoid high mountain areas, areas with intensive agriculture, industrialised and urban areas. In comparison, feral cats (domestic cats living in the wild) appear to be to some extent dependent on human habitation. In Scotland home ranges are larger in the west than in the east due to differences in habitats and prey abundance and can vary from 0.3 to 18 km2 . Rabbits appear to be a particularly important prey species, but wildcat populations can persist on a diet of largely mice and voles.
If the answer to both questions is yes, a survey is recommended as a reasonable check to avoid causing an offence to this rare and threatened protected species.
When deciding what type of survey is required, a hierarchical approach is proposed.
3. A walk-over survey should aim to establish if there are potential dens sites2 present on the site or nearby. Together with desk information, the survey should also inform the extent of wildcat habitats affected by the proposal.
2 Den sites/ resting locations - Detailed information on den sites in Scotland is scarce. They are thought to favour rocky cairns and boulders, tree hollows, under root plates and dense gorse etc., but may also use fox earths, badger setts or rabbit burrows. Studies in mainland Europe have revealed the diversity of locations used by wildcats; including dense and tall vegetation - not all providing shelter from the rain. Hence in Scotland, areas of bracken, tall grasslands and brash in forestry may also be important for at least temporary shelter. Den sites will tend to be close to food sources such as rabbit warrens and woodland edges. South facing slopes may also be favoured. The same animal is likely to use several locations for shelter within its home range, other than when a female has kittens. Recent use may be indicated by the flattening of vegetation, smoothing of bark on branches, hair or prey remains. Scats are not commonly found at den sites.
4. Detailed surveys will likely only be required where evidence of wildcats is found during initial surveys and there is a need to distinguish wildcat signs from those of other species.
Details as follows:
1. Are there local records of wildcat sightings/ is there local knowledge of wildcat presence?
Most recent wildcat sightings are published on the NBN. This includes the records from the NatureScot survey between 2006 and 2008.
Search for the term ‘wildcat’ and select the interactive map. This allows you to zoom in on an area of interest and using the cog on the ‘species’ tab you can select the time period from which you want to examine records. Post 1980 presents the records that illustrate what is considered to be the current wildcat range and includes records from the comprehensive Nature Conservancy Council survey in the late 1980’s. Records from after the year 2000 perhaps reflect more recent records, although there are fewer records for this period and hence more gaps. It is not possible to say if this reduction in records reflects a decline in Scottish wildcat numbers and distributions or is simply a result of differences in survey methods/ effort over the two periods.
If there are wildcat records from the same 10km square or within a 10km radius of a proposed development, it is reasonable to consider that wildcats may be present. NBN records may be supplemented by local knowledge, for example by speaking to local landowners and managers or naturalists and field clubs.
Where wildcats are known to be in an area from one or other sources, the next step is to consider whether the proposed development has the potential to affect wildcat habitats.
2. Will the proposed development affect wildcat habitats?
A risk based approach to survey is suggested based on our knowledge of wildcat habitat preferences. To assist this process NatureScot has developed a Wildcat Habitat Suitability Model. This is intended to help inform where site surveys will be most important and avoid the need for surveys in areas unlikely to support wildcats.
The model is based on selecting suitable ‘cover habitats’ (woodland, scrub and tall vegetation) and ‘prey habitats’ from land cover maps. The model also incorporates a buffer area through which wildcat movements between these habitat patches is most likely (i.e. a cost distance model). For more details please contact Jenny.Bryce.
However, we caution against using such modeling in the absence of other information sources, such as OS maps, aerial photographs and local knowledge to confirm the presence of suitable wildcat habitats. In areas with wildcat records and suitable habitats, we advise you to carry out a walk-over survey at an early stage.
3. Walk-over survey
Surveys will in most cases be looking for evidence of dens or resting sites, but other signs may also be found that indicate use of the site by wildcats. For all EPS, surveys should be carried out prior to planning permissions being granted (where required).
Survey area and timing - A walk-over survey is recommended informed by OS maps, aerial photos and where available, habitat maps. Recognising that some development proposals cover large areas with difficult terrain; a risk based approach is proposed with a focus on the most preferred habitats. Where it is not possible to survey the entire development footprint, survey effort should focus on woodland rides and clearings, burnsides, rocky habitats, rabbit warrens, areas of juniper, bracken, gorse and broom. Surveys should include a 200m buffer around the footprint of the development to account for potential disturbance to nearby dens and resting sites. Surveys are best done in the autumn and winter, after breeding and when vegetation is less likely to obscure den sites; and particularly after snow when footprints can be clearly seen.
Evidence - The walk-over survey should look for potential den sites and any other signs of wildcat presence. You do not need a licence to carry out this sort of survey. If a potential den site is located, it should either be treated as a wildcat den on a precautionary basis, or further survey is likely to be required to determine if it is used by wildcats or another species (noting that different species may use the same den at different times). See section 4 for detailed surveys. If you do discover a den site, you should leave the area with minimal disturbance and seek advice from NatureScot.
The structure of a wildcat den is protected whether or not it is in use at the time. However, the risk of disturbance is greatest when there is evidence that a den site has been in recent use. Strictly the protection relates to the den structure, but extensive changes to the surrounding habitats could render a den site/s nolonger viable.
4. Detailed surveys: trail cameras or genetic testing
If a walk-over survey reveals possible den sites or wildcat signs you should consider whether it is possible to modify your proposals to avoid any negative impacts on wildcats. If this action is not possible, a detailed follow-up survey may be required to determine if the structures or signs are those of a wildcat, feral cat, hybrids or another species.
Where there are signs of den use by a predator, trail cameras can be used to gather evidence of whether this is likely to be a wildcat. A minimum survey period of one month is recommended. Commissioned Report 479 contains advice on how to set up cameras for wildcats. The use of trail cameras at a potential wildcat den requires a survey licence from NatureScot, so please refer to Licensing the conditions of which aim to minimise disturbance.
Any photographs of wild-living cats should be assessed against the pelage classification illustrated on the Highland Tiger website. Any cat that meets the ‘field definition’ should be regarded as a wildcat.
Where there are cat signs that are not associated with a den site, trail cameras could help to indicate whether the site is used by feral cats or wildcats. However, where there is already local knowledge or credible records to indicate there are wildcats present, this may not greatly add to existing knowledge; that the site may occasionally be used by wildcats.
A second detailed method that may help to discriminate between wildcats, feral cats and hybrids is the genetic testing of scats or hair for DNA. A number of laboratories may be able to offer testing services. Scats can be collected during a walk-over survey, focusing on habitat boundaries e.g. woodland edge.
Elsewhere in Europe wildcat hairs are routinely collected using rough wooden scratching posts daubed with a scent lure. Clumps of hair that are snagged can then be tested for their DNA.
Live-trapping could also be used to distinguish wildcats from feral cats. However, this method is unlikely to be licensed solely for the purpose of establishing wildcat presence