Bird Island is a sandy cay rising only a few metres high, situated on the northern edge of Seychelles Bank about c.100 km north-west of Mahé. It is very young, perhaps having emerged no more than 4,000 years ago. The island was sparsely vegetated and supported large numbers of seabirds until the end of the nineteenth century. Coconut-palms Cocos nucifera were then planted over most of the island, but were partly cleared after 1967 to encourage the breeding of Sterna fuscata. About 70% of the island is now covered with mixed woodland. This includes the remaining coconut plantation, areas planted with Casuarina equisetifolia and Pisonia grandis forest that has been allowed to regenerate in the centre of the island. Main human activities are tourism (there is a small hotel served by plane from Mahé), small-scale fisheries and aquaculture.
See Box for key species. The island supports a huge and increasing breeding colony of Sterna fuscata. More than one million are present during the breeding season between April and October; the species is rare or absent the rest of the year. There is also a large colony of Anous stolidus. Other breeding species include Puffinus pacificus (uncommon), Gygis alba (720 pairs), Anous tenuirostris (300 pairs, increasing) and Phaethonlepturus (10–20 pairs). A population of Streptopelia picturata (30–60 individuals) is also present, with many individuals showing characteristics of rostrata. Non-breeding visitors include more than 250 Sterna saundersi and 5,000 S. anaethetus.
Non-bird biodiversity: The island hosts one species of skink and one species of gecko endemic to Seychelles. Green turtles Chelonia mydas (EN) nest in larger numbers than elsewhere in the granitic islands and hawksbill turtles Eretmochelys imbricata (CR) also breed; numbers of both are monitored. A small number of the giant tortoise Dipsochelys dussumieri have been introduced.
Pressure/threats to key biodiversity
The island was declared a wildlife sanctuary by the owner in 1986, but it does not have any legal protected status. Its management is oriented towards both conservation and tourism. Grass is burnt every year in March–April to improve nesting habitat for Sterna fuscata. The colony is not now exploited for commercial egg production, although some egg-collection by residents for personal consumption occurs. A long-term research programme on Sterna fuscata colony began since 1972 and a study of Anous stolidus was completed recently. Rats were eradicated in 1996 and it has been suggested the island is potentially suitable for the translocation of threatened endemics sensitive to rat predation. Unfortunately, in 1998 the island suffered an invasion of introduced crazy ants Anoplolepis gracilipes, which infested the Sterna fuscata colony. Programmes to eradicate the ants are being conducted. Because of its isolation, Bird Island may be the best place to maintain a population of Streptopelia picturata of the endemic race rostrata before it completely disappears. Beach erosion is a cause for concern.
BirdLife International (2019) Important Bird Areas factsheet: Bird Island (Ile aux Vaches). Downloaded from
http://www.birdlife.org on 14/12/2019.