The Jewel of the Forth Guidebook - Exploring the Isle of May NNR

Note: Isle of May NNR map and guidelines are available.

Welcome to the Isle of May

The Isle of May National Nature Reserve (NNR) is owned and managed by NatureScot. Lying at the mouth of the Firth of Forth, the island is 1.5km long and 0.5km wide.

This iconic reserve is hugely significant for its thousands of breeding seabirds in the summer and internationally important grey seal nurseries in the autumn. During the spring and autumn, the island is also one of the most important migration stations on the east coast for migrant birds travelling to summer and wintering grounds.  

In 1956 the Isle of May was designated as a National Nature Reserve. It has many other national and international designations; they help to ensure the habitats and species found here are protected. We manage the island sensitively to conserve it for the future and to keep the precious wildlife safe. Please help us keep it that way and enjoy your visit.

The importance of the Isle of May

The island is made up of greenstone (olivine-dolerite), forming the high west cliffs which reach 45 metres in height. These cliffs provide perfect breeding ledges for cliff-nesting birds. It slopes from the west cliffs to shallow rocky shores on the east.

The whole island is covered by a shallow layer of soil and maritime grassland; a perfect place for burrowing puffins and groundnesting birds.

The island is a safe haven for the thousands of seabirds as there are no mammalian predators such as rats and foxes that would predate eggs and young. The nutrient-rich seas are excellent fishing grounds for sprats, herring and sand eels – food sources for the seabirds and seals.

The island has a deep cultural history spanning 1,000 years with early Christianity dating back to the seventh century.

In more modern times, lighthouses played an important role for navigation through the Forth with Scotland’s first ever lighthouse built on the island in 1634.

Cliff nesters

Guillemot

Known as the ‘Northern penguin’, guillemots breed in large colonies laying a single egg on cliff ledges. Adults return to breeding ledges in March and will be there until July when the flightless chicks take a leap of faith from the cliffs, before spending the winter out at sea.

Guillemots, along with their close relatives the razorbill and puffin, are excellent divers. Using their wings as flippers they can dive to depths of 200 metres in search of prey.

Check the west cliff viewing areas to see thousands of guillemots huddled together protecting their eggs and chicks.

Razorbill

Razorbills are shy birds and often breed in individual pairs tucked away in nooks and crannies.

Like the guillemot they lay a single egg directly on to the bare rock. They don’t build a nest as the egg has a hard shell and is pear shaped to minimise the risk of it falling off ledges.

Look for the bright yellow colour on the inside of their bill, which helps adults find chicks in dark nesting crevices.

Above and below

Puffin

The island’s most numerous and iconic seabird, puffins arrive back on land in early April to find their lifelong mate and their burrow.

The female lays a single egg with both parents taking turns to incubate for 40 days. It will be a further 40 days before the chick leaves the safety of the burrow and makes its way to the sea, where it instinctively knows how to dive and catch fish on its own.

Puffins are able to carry more than one fish at a time, an efficient way to feed hungry chicks. Some have been known to hold over 60 fish in their bill at once. Having small barbs in the roof of their mouth enables them to hold onto their catch whilst hunting for more.

Puffin lifecycle

• Return in late March
• Egg laying mid-April
• First chicks hatch late May
• First chick fledge in early July
• Last chicks depart early August
• Mid-August all adults gone and do not return until next March

It is important to stay to marked paths and boardwalks to avoid damaging underground puffin burrows and their inhabitants.   

Large gulls

The Isle of May has three different large gull species breeding: herring, lesser black-backed and the larger great black-backed gull.

All build a nest on the ground from vegetation and seaweed as well as any rubbish they find that looks good for nest material. They lay between one and three eggs.

Both adults will incubate and feed the young, bringing back both fish and scraps from landfill sites 30-40km away on the mainland.

Terns

Arctic and common terns breed here every year. Sandwich and roseate terns only breed occasionally but can often be seen flying over. Terns are the last of the breeding birds to arrive as they have the furthest to travel from their wintering grounds.

Arctic terns have the longest annual migration of any creature on earth, wintering in the Antarctic before flying back to the Northern hemisphere to breed in our summer. One tracked bird clocked up 100,00km in one year!

Adult terns protect their nests by dive-bombing any animal or human that gets too close so beware when walking past the colony. Watch your feet as eggs and chicks are highly camouflaged.

Eider

Male and female eiders have different plumages. Colourful males display to females, throwing their heads back and making a ‘wooo’ call to attract a mate.

The well-camouflaged female makes a cosy nest lined with down. Once the chicks hatch the female walks them to the water to start feeding, forming crèches with many females looking after a number of ducklings.

The loch on the west of the island is a great place to see male eiders displaying to females in April/May and the crèches in June.

Along the coast

Shag

A close relative of the cormorant, shags have a green iridescence to their feathers, displaying their shaggy crest during the breeding season. They are comical to watch when nest building, carrying a variety of materials from seaweed and grass to old rope and rubbish that is found around the shore. They often steal material from their neighbours.

Fulmar

Fulmars spend long periods soaring low over the sea in search of food, feeding on fish, plankton and carrion. They have a great sense of smell and can locate rotting flesh up to three miles away. They nest on ledges and crevices at the tops of cliffs.

Fulmars are almost gull-like but are related to the albatrosses. They have specialist tube noses and fly with very stiff wings, with shallow wingbeats, gliding and banking over the cliffs. 

Kittiwake

Kittiwakes are the true ‘sea-gull’ of Britain spending all their life around coastal waters, venturing as far as Greenland and Canada during winter. They arrive at the island in early spring, pair bonding on ledges and calling their name “kittiwake” loudly. Their nests are made of dead grass and mud, just a small bowl stuck precariously on cliff ledges.

Under the sea

Grey seals

Grey seals can be seen around the island throughout the year especially at low tide at the Maidens and Rona. Numbers increase dramatically in early autumn when females prepare for the pupping season.

The first pup is usually in late September. Over 2,200 will then be born between October and December.

Females move up the island spending three weeks with the pup feeding and protecting them. Males will follow and defend a small harem from other males, mating with the females when ready.

After three weeks suckling rich fatty milk, the pup triples in weight and moults its white coat revealing its darker waterproof coat. It is now independent, ready to learn how to find fish and feed itself.

The UK holds over 40% of the world’s population of grey seals with the island having a high proportion of that total.