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RESTORATION OF WESTERN INDIAN OCEAN ISLANDS CONTINUES APACE

Front cover - Tropical Island Recovery: Cousine Island, Seychelles

Tropical island species and ecosystems are threatened worldwide as a result of increasing human pressure. Yet some of these islands also lend themselves to restoration, as they are physically defined units that can be given focused attention. Cousine Island, Seychelles, is a tropical island that has received such intensive restoration. From a highly degraded island in the 1960s, the island has now been restored to what is believed to be a resemblance of the natural state. All alien vertebrates have been eradicated, as have 25 invasive alien plants. Cultivated plants are now confined to one small section of the island.

With the successful restoration of Cousine Island, Seychelles, well underway there has been a surge of interest in restoring other islands in the Seychelles. Some of the initiatives have been very successful, with both North and Frégate Islands having eradicated rats, a major predator of seabirds, skinks and many invertebrates. C·I·B core team member, Michael Samways, recently set up a restoration protocol for Desroches Island in the Amirantes group of islands in the Seychelles. The Amirantes are sandy cays and geologically recent (only a few thousands of years old), which presents different challenges to restoration in comparison with the granitic islands of the Seychelles, such as Cousine, which are of Gondwanan origin. These granitics are rich in endemics, and it is crucial to establish the historic condition before restoration can begin. Sandy cays, in contrast, are more forgiving in the approach that is taken, and can be used as an ark to maintain populations of species which are severely threatened in the granitics.

Desroches traditionally has been used extensively for copra (south pacific name for dried sections of the meaty inner lining of the coconut palm) production from coconut palms and for timber production from casuarina trees. With a move to high value ecotourism, away from more traditional low-income agriculture, there is a need to replace the coconut palms and casuarinas in the central areas of the island with what is considered the natural vegetation, consisting of Hernandia, Guettarda, Cordia and Pisonia trees. A nursery is now being set up to propagate these and some other indigenous tree species. With recovery of the native vegetation, it is likely that more seabirds will be present on the island as the vegetation matures towards good roosting and nesting sites. Significant challenges remain, especially eradication of rats. Consideration is also being given to introductions of various rare birds and invertebrates of the Seychelles, with Desroches then playing a role in their long-term survival.

For further information see Samways M.J. et al. 2010 Tropical Island Recovery: Cousine Island, Seychelles, Wiley-Blackwell, Oxford, UK. ISBN: 978-1-4443-3309-1.