The ecology and conservation of the Aldabran brush warbler Nesillas aldabranus

The Aldabran brush warbler, Nesillas aldabranus, is one of the world’s rarest birds. Studies conducted over the course of 2 years indicate that its distribution is probably restricted to one small area of Aldabra Atoll. Within this area it inhabits only one vegetation community, dense ‘mixed scrub’, and even within this it is very patchily distributed. Only five separate individuals were definitely identified during the study, but these included two pairs which held contiguous territories. Aspects of the ecology and behaviour of the species are described. The extremely rough and densely vegetated habitat in which the brush warblers live prohibits an accurate estimate of total population size, but it is probably below 25 individuals. Possible conservation measures are discussed in the light of the information collected.