Flat Holm - Flora and Fauna

Flora and Fauna

Flat Holm was designated a Site of Special Scientific Interest (SSSI) in 1972. The designation covers the maritime grassland which is mainly concentrated around the edges of the island.

There are no endemic plant species but the relative isolation of the island has allowed a number of hardy species such as Bird's-foot Trefoil (Lotus corniculatus) and Biting Stonecrop (Sedum acre) to thrive. There are also a number of relatively rare plants, such as Rock Sea-Lavender (Limonium binervosum), and Wild Leek (Allium ampeloprasum). The leek grows to 6 ft (1.8 m) and Flat Holm is one of only five places in the UK where it is found. Related to the onion, the leek has a bulb that grows for several years producing only leaves, then blooms with large purple flowers that smell of garlic. After flowering the bulb dies and produces up to 150 bulblets.

Others plants may have been introduced by the Augustinian Community for their medicinal uses. These include Dove's-foot Crane's-bill Geranium molle, an anodyne plant claimed by Nicholas Culpeper to have a wide range of medicinal uses and an "excellent good cure for those that have inward wounds, hurts, or bruises, both to stay the bleeding, to dissolve and expel the congealed blood, and to heal the parts, as also to cleanse and heal outward sores, ulcers and fistulas". The Wild Peony (Paeonia mascula) was introduced to the island (and nearby Steep Holm), possibly by monks, and has naturalised. Thirty-seven plants were taken to the island from Steep Holm by Frank Harris, the farmer at the time, in the 1930s, many of which died during the World War II occupation and fortification of the island. One remaining plant was reintroduced by David Worall, the Flat Holm Warden, in 1982 and is protected by fencing near the path to the lighthouse. A few plants grown from seed also survive in the island's farmhouse garden.

The island has a significant breeding colony of over 4,000 pairs of Lesser Black-backed Gulls (Larus fuscus), 400 pairs of Herring Gulls (Larus argentatus), 2 pairs of Great Black-backed Gulls (Larus marinus) and varying numbers of Common Shelduck (Tadorna tadorna) and Eurasian Oystercatchers (Haematopodidae). The feeding habits of Lesser Black-backed Gulls were studied in 1989, and it was shown that smaller clutches were laid than in previous years and that supplementary feeding did not increase egg or clutch size.

The island is also home to slow worms (Anguis fragilis). Flat Holm's slow-worm population has unusually large blue markings.

The island's rabbit population, introduced for farming in the 12th century, suffers from myxomatosis, which effectively contains the numbers. The island has been grazed since 1989, initially by goats, but also by sheep since 1992. In 1997 Soay sheep were introduced and as of 2008 there are 28 sheep grazing wild on the island.