MOrtality of captive-raised malleefowl, Leipoa ocellata, released into a mallee remnant within the wheat-belt of New South Wales

Abstract

Loss, fragmentation and degradation of mallee habitat within the New South Wales wheat-belt have caused a marked decline in the range and local abundance of malleefowl, Leipoa ocellata. Small disjunct populations of malleefowl now occupy small isolated remnants of suitable habitat. and several of these populations have become locally extinct in recent times. Young captive-reared malleefowl(8-184 days old) were experimentally released in March and June 1988 into a 558-ha remnant of mallee vegetation. The remnant contained a small but declining population of rnalleefowl. From the first day after release, malleefowl were found dead, and mortality continued at a rapid rate until none remained alive. Of the 31 released, 16 (52%) were dead after 7 days, at least 22 (71%) were dead after 11 days, and none survived longer than 107 days. In all, 94% of malleefowl were killed by predators: 26-39% by raptors, and 55-68% by introduced predators, principally foxes, Vulpes vulpes. No improvement in survival was evident when malleefowl were given supplementary food. Relying principally on camouflage, young malleefowl have no effective defence or escape behaviour to evade ground-dwelling predators such as the fox. By imposing severe predation pressure on young malleefowl, foxes are likely to be curtailing recruitment into the breeding population. Such a situation must inevitably lead to the further localised extinction of small disjunct populations of malleefowl. Foxes are thus a major threat to the continuance of remnant populations of malleefowl within the wheat-belt of New South Wales.