Previously a coconut plantation, Cousin Island was purchased by the International Council for Bird Protection (now BirdLife) in 1968, for the immediate purpose of saving the endemic Seychelles Warbler Acrocephalus sechellensis. 26 warblers had been found in the mangroves of the island clinging perilously to life, with much of its original habitat converted to coconut plantations. A campaign was started to rescue these birds and they became the flagship species for the island.
To save the warbler, a habitat restoration programme was implemented: Cousin’s coconuts were cut back and native vegetation encouraged to regenerate, which allowed the warbler to flourish. Its numbers increased. Soon over 300 birds could be heard singing on Cousin. From here the warbler was re-introduced to other islands in the Seychelles to boost its population and the bird now occurs on five other islands in the Seychelles.
The aim of the recovery plan for the Seychelles Warbler was to have 5000 individuals flourishing on five islands and to have it down-listed in the Red Data list.
The transformation of the island from an ecologically impoverished coconut plantation into a thriving indigenous forest also benefitted other species notably the Seychelles Magpie Robin, Copsychus sechellarum. The first step in the rescue of the this bird, also once on the brink of extinction and clinging to life on Fregate Island, was the establishment of a population on Cousin. Other bird transfers to and from islands have been carried out and it now survives on six islands.
Cousin is a huge conservation success. The previous coconut plantation is now mainly a native forest dominated by Pisonia grandis, Morinda citrifolia and Ochrosia oppositifolia. There are wetlands where fresh water attracts dragonflies and moorhens; the hill creates ideal nesting sites for shearwaters and bridled terns; on the seashore, crabs and shorebirds abound. It is home to a number of reptiles such as giant tortoises and five endemic lizards, giant millipedes and hermit crabs. Seven species of nesting seabirds, in numbers exceeding 300,000 individuals call Cousin home.
The island is recognized as one of the most important breeding sites in the Western Indian Ocean for Hawksbill turtles, and the monitoring programme for this species was put in place in 1972. Since then an eight-fold increase in nesting turtles has been recorded.
Five of Seychelles’ eleven endemic land birds – Seychelles magpie robin, Seychelles sunbird, Seychelles fody, Seychelles blue pigeon and the Seychelles warbler – are found on Cousin.
Of the nesting seabirds, Fairy terns Gygis alba and White-tailed tropicbirds Phaethon lepturus nest all year round, whilst Lesser noddies Anous tenuirostris, Brown noddies Anous stolidus and Bridled terns Sterna anaethetus have different breeding seasons. Two varieties of shearwaters, Audubon’s shearwater Puffinis lherminieri and the Wedge-tailed shearwater Puffinus pacificus are found. The former breeds all year round whilst the wedgetailed shearwater breeds from May to October. 300 or more species of fish are found in the marine area and prior to the coral bleaching of 1998 it had the largest fish biomass of any reserve in the granitic Seychelles.
Since 1998, Cousin is managed by Nature Seychelles, a national nonprofit organization (NGO) and BirdLife Partner.