The destruction of source and sink habitats in the decline of the Mauritius Fody, Foudia rubra, an island-endemic bird

The population of the Mauritius Fody, Foudia rubra, a rare island-endemic bird, was structured as five subpopulations. The largest comprised small source areas contiguous with larger sink areas. The remainder were relicts, left by habitat destruction, from a time when the distribution was far more extensive. No evidence was found for a classical metapopulation structure. Destruction of source areas would have severe effects on population viability; their creation is the key to enhancing it. Following habitat destruction (1950-1975), fodies unexpectedly disappeared from habitat areas that were not destroyed; this probably occurred because the area destroyed contained source areas upon which adjacent, intact sink areas depended. The suggestion that introduced nest predators are likely only to affect native animal populations soon after their arrival is strongly rejected.