Survival of captive-reared malleefowl Leipoa ocellata chicks released into experimental enclosures within Yathong Nature Reserve, New South Wales, Australia

Background

This study investigated the survival of captive-reared malleefowl Leipoa ocellata chicks released into 1-ha enclosures of natural mallee vegetation (e.g. Eucalyptus and Acacia spp.), with and without supplementary food and water, at Yathong Nature Reserve (32°40'S, 145°30'E), New South Wales, south-eastern Australia.

Action

During January 1987, malleefowl eggs were collected from nesting mounds near Yalgogrin (33°49'S, 146°46'E), and transported to Yathong Nature Reserve for artificial incubation. After hatching, chicks were reared in an outdoor holding pen until approximately one week old, when they were released into four 1-ha enclosures that had been established in 1985 (and hence not grazed for two years), and which were surrounded by an electric fence to exclude mammalian predators. One enclosure contained supplementary food in the form of ‘budgie mix’ seed, which was provided in 25 open-topped dishes (160 g in each) and liberally dispersed throughout the enclosure (a further 20 kg). A second was provided with a drinking trough of water. A third was supplied with water, but also contained 15 rabbits Oryctolagus cuniculus. The final enclosure was left unmanipulated, as a control.

All chicks (which had been fitted with miniature radio-transmitters) were located daily to monitor survival and determine the cause of any mortality.

Consequences

Of the nine chicks released into the seeded enclosure, eight (89%) survived for 30 days (the duration of the trial). The ninth survived for six days, but then died after being drenched by heavy rain. Of the 20 chicks released into the other three enclosures, 17 (85%) had died within eight days, and none survived more than 22 days. Six were predated by raptors, five died of starvation, five died of chilling following heavy rain, two died of unknown causes, one died of a cloacal blockage, and one was removed after it fractured its leg. All were found to have little or no food in the crop or gizzard, suggesting that food shortage was a contributing factor in all their deaths.

The authors concluded that, although the enclosures provided protection against mammalian predators, the 1-ha plots of mallee vegetation could not sustain malleefowl chicks without the provision of supplementary food.

Note: If using or referring to this published study, please read and quote the original paper, the abstract of which can be viewed at: http://www.publish.csiro.au/nid/96/paper/MU9900081.htm.