Population monitoring for the flightless rail Dryolimnas cuvieri aldabranus

Abstract

The last flightless bird of the western Indian Ocean, Dryolimnas cuvieri aldabranus survives only on Aldabra. Its population numbered some 8,000 in 1973–1976. Surveys suggest numbers remained roughly constant between 1968 and 1988 (with a fluctuation of only 4% in responses to call playback between 1983 and 1988), but distribution continued to contract. Longevity can reach over 8.5 years (but is probably lower on average), and some birds remain within 100 m of the site of ringing for at least five years. Feral predators remain a threat, and captive populations are recommended. The monitoring procedure may have value for other Gruiformes. © 1993, Birdlife International. All rights reserved.