Cousine island is situated 5 km south-west of Praslin, 2 km from Cousin. The main part of the island is formed by a ridge of ancient granite rising to 70 m, overlooking a small coastal plateau on the eastern side, fringed by a 1 km long sandy beach. The rest of the island is surrounded by a rugged, rocky coastline. The hill is covered by closed-canopy woodland dominated by Ficus nautarum, F. reflexa and Pisonia grandis. The plateau retains small patches of this woodland, the remainder now being covered with scrub and grassland. The island was formerly exploited for coconuts (Cocos nucifera), planted extensively during the twentieth century, and for seabirds (mainly shearwaters). These activities were abandoned in the 1970s and coconuts are being progressively eliminated. A small orchard and garden has been kept for the few resident staff. The coral reefs around Cousine hold a rich marine life and some traditional fishing takes place. It has a helicopter pad and a small-scale, high class tourist facility.
See Box and Table 2 for key species. This IBA is one of only four major sites in Seychelles with populations of Copsychus sechellarum, (13 birds in 1999, from three pairs introduced in 1995), Acrocephalus sechellensis, (137 birds and 42 territories in 1997, from 29 birds introduced from Cousin in 1990) and Foudia sechellarum (450–670 birds in 1996). In addition, Nectarinia dussumieri, Alectroenas pulcherrima (tens) and Streptopelia picturata x rostrata (c.200 birds) also occur, of which some individuals show the characteristics of rostrata. Other landbirds include Gallinula chloropus (min. 84 birds), Butorides striatus (4–6 birds) and the exotic Geopelia striata and Foudia madagascariensis. Cousine is also important for breeding seabirds, with the large largest colony of Puffinus pacificus in Seychelles. In addition to those listed below, Puffinus lherminieri nicolae (hundreds of pairs), Anous stolidus (c.900 pairs) and Sterna anaethetus (c.50 pairs) also breed. Some 1,300 pairs of Gygis alba were present in July 1999 and it is thought that more than 5,000 pairs probably nest during the course of the year. Non-breeding Fregata ariel and F. minor occur regularly in mixed flocks. Numenius phaeopus and Arenaria interpres and, less frequently, Dromas ardeola can be found throughout the year along the coastline.
Non-bird biodiversity: Two species of skink endemic to Seychelles, Mabuya wrightii and M. seychellensis, occur at extremely high densities. Other abundant endemics include several species of geckos (Phelsuma spp. and Ailuronyx sp.) and invertebrates. A small population of the endemic snake Lycognathopis seychellensis also occurs. Hawksbill turtles Eretmochelys imbricata (CR) nest on the beach.
BirdLife International (2019) Important Bird Areas factsheet: Cousine island. Downloaded from http://www.birdlife.org on 22/04/2019.