Skinks can adapt on bird colony islands, says study |23 May 2005

The Seychelles skink – which is common on most of the granitic islands and has introduced populations on coral islands – has taken over the role of Wright’s skinks where they have gone extinct, according to a report by Dr Justin Gerlach of the Nature Protection Trust of Seychelles.

The report was published in the latest issue of the African Journal of Herpetology.

“For 50 years the identity of the skinks on some small islands has been a puzzle as the skinks appear to be exactly halfway between Seychelles skinks and Wright's skinks,” Dr Gerlach said.

Wright’s skinks are restricted to islands with seabird colonies, where they are able to feed on fallen fish and dead birds during the main tern breeding season.

But on some islands confusion over identification has been caused by the extinction of one species and colonisation by the other.

“This has happened on Marianne and Isle aux Vaches Marines where tern colonies are extinct or have abandoned the island for several years,” Dr Gerlach said. “This led to the extinction of Wright's skinks but Seychelles skinks were able to survive.”

Since terns returned to Isle aux Vaches Marines the Seychelles skinks are now becoming more like Wright’s skinks, he added.

“They are becoming larger and resemble Wright's skinks in order to take advantage of the presence of the breeding terns, but their real identity as Seychelles skinks is given away by obscure features such as their number of scales and the shape of their nostrils,” said Dr Gerlach. “This constant change in the populations of skinks shows both how adaptable nature can be and also how dependent some species are on their environment. In the absence of terns, Wright's skink cannot survive for long, but their decline provides new opportunities for other skinks.”

Seychelles is home to four species of skinks – the burrowing skinks Pamelascincus gardineri and Janetascincus braueri, and the larger Seychelles and Wright's skinks.