Translocation of Seychelles warbler Acrocephalus sechellensis to establish a new population on Denis Island, Seychelles.

In December 2011, 59 adult Seychelles warblers Acrocephalus sechellensis were translocated between two islands in the Seychelles. Birds were captured on Cousin Island and translocated to Fregate Island using a hard release method, with minimum time in captivity. Fregate had been previously identified as a suitable host for a substantial population of Seychelles warblers, although the presence of the species had never been confirmed on this island. It was estimated that Fregate currently has the potential to support about 500 Seychelles warblers, rising to over 2,000 after habitat regeneration. All birds survived the translocation and were released unharmed at the new site within 24 hours of capture. Close monitoring of both the new and source population was undertaken over a period of 18 months. By June 2013, the Fregate population had increased to 80 individuals, which included 38 of the original translocated birds and 42 birds which had hatched on Fregate. There was also evidence that multiple generations had already hatched on the island. This shows that the Seychelles warbler responded well to a hard release translocation, with observed population growth on Fregate comparable to previous warbler translocations. The source population on Cousin recovered to carrying capacity within a single breeding season. This is the fourth translocation of this species, fulfilling the species action plan requirement of five populations of this endemic island passerine.