Group size and composition in the Grey-crowned Babbler 'Pomatostomus temporalis' in an urban environment

Abstract

The Grey-crowned Babbler 'Pomatostomus temporalis', a cooperatively breeding woodland bird, is declining in the southern parts of its range where its social dynamics and reproduction have been negatively affected by fragmentation and degradation of suitable habitat. We studied 12 groups of Grey-crowned Babblers in and around Dubbo, New South Wales, eight in altered habitat and four in the surrounding natural habitat of Ironbark/Cypress woodland. Individuals were captured and colour-banded and weighed. Feather samples were collected for DNA analysis to determine the sex of individuals. There were no significant differences between groups in natural and altered habitat in sex ratio, group size, or mean weight. Mean group size was 6.7 birds, with a mean of 3.3 young birds from the previous two breeding seasons, figures comparable with or better than those in groups from more natural habitats in Queensland and New South Wales. Mean weights were similar to those of birds in the Pilliga Nature Reserve 230 kilometres north of Dubbo, but heavier than those in Queensland. Generally, the population of Grey-crowned Babblers inhabiting areas in and around Dubbo seems to be healthy, although this may change as the city grows.