Back in the 1960s, the Seychelles Warbler or Timerl Dezil was probably the most endangered bird in the world, with only a handful of birds remaining. Cousin Island, the last place it survived, was purchased primarily to save this unspectacular but unique bird. Much has been done by BirdLife International to save the species. Now, Nature Seychelles has been working with our partners on Denis Island and scientists from the University of East Anglia in the UK and Groningen in the Netherlands on a major project to secure the future of the species.
The Seychelles Warbler - once confined to Cousin Island with only 26 birds - now thriving on four islands, and back from the brink of extinction © W. Meinderts
In June 2004, along with our partners we organised for 58 adult birds to be translocated by helicopter from Cousin to Denis. The habitat on Denis had been enhanced by our work in eradicating alien plants and establishing native trees. We were as confident as we could be that, thanks to the hard work of all involved, the restored island was ready for the Warblers. But of course nothing is certain in nature.
Happily, close follow-up of the released birds shows the operation to have been a success. Pairs formed just five hours after release. These first pairs started nest-building within three days of arrival. In total, 20 territories were located, of which 15 had breeding attempts. In January 2005, researchers made a five-day visit to check on the population. Many young birds were observed, some of which were already nesting. Breeding seemed to be continuous. A complete survey has been done between June and September 2005 to see how well the population is faring one year on.
The study also looked at how the Cousin population has been 'filling any gaps' left when the 58 birds were removed. Just five hours after release. These first pairs started nest building within three days of arrival. In total, 20 territories were located, of which 15 had breeding attempts. All but two of the birds were seen again in 2004.
The signs are that the Denis population is continuing to flourish, and the Cousin population from which it originated has recovered to its original level. This is more great news for conservation in Seychelles, and adds to our knowledge of how habitat restoration to re-establish populations of endangered species can work.
The research team has also been looking at the Warbler's cooperative breeding system. Young birds from one brood will often help with the rearing of subsequent broods, by a combination of joint nesting – more than one female laying eggs in the same nest - and helping to feed the young at the nest.
The researchers are also studying the effects of parasites on the health and vitality of the warblers, and at how the birds disperse to occupy new territories.