Nesting activity and demography of an isolated population of malleefowl (Leipoa ocellata)

Abstract

Nesting activity of a population of malleefowl (Leipoa ocellata), isolated within a small mallee remnant in central New South Wales, was monitored annually between the summers of 1986–87 and 1998–99. A total of 148 nesting events was recorded. Only once was a new mound constructed rather than an old one reworked. Birds began and finished work on the mound progressively later each month (October to January). Nest-site fidelity was highly variable; some pairs persisted with the same mound for up to nine years while others relocated between a cluster of two, three or four mounds. Males displayed greater nest-site fidelity than females. After the loss of a partner, males tended to continue to use mounds they had used previously whereas females often relocated to a new mound. All individuals were monogamous. Pair bonds were maintained for life but, following the death of a partner, new bonds were quickly established with another unattached individual. Established pairs occasionally failed to breed, all such failures being coincident with years of low rainfall. Pairs that did not breed generally began construction of a nest but failed to complete the task. As far as can be ascertained, unpaired birds did not construct nests. The malleefowl population was characterised by a rapid turnover of breeding individuals, a high rate of adult mortality and a lesser rate of recruitment. The maximum longevity recorded for breeding adults was 12 years; average longevity was 7.5 years. Twenty-five adults were lost from the breeding population over a period of 9 years; meanwhile, 14 birds entered the breeding population. Thus, the ratio of adult mortality to recruitment was 1.79 : 1.00. Between 1986–87 and 1997–98 the population declined from at least 32 breeding adults to 14, at an average exponential rate of decrease of 0.075. Large population decreases were coincident with years of low rainfall. This population of malleefowl is predicted to become extinct by 2008.