Habitat use, home range and diet of male Victoria's Riflebird, Ptiloris victoriae

Abstract

Dispersion, movements and diet of male Victoria's Riflebirds, Ptiloris victoriae, were studied in a vegetation mosaic dominated by rainforest and regrowth. Habitat use within the mosaic was assessed by a series of point surveys along transects through each habitat. The home ranges of eight males with display areas on the study site were mapped by observation of marked males (three birds) and by following unmarked males (five birds) as they moved between display posts or foraged. Diet was examined by a combination of observations and faecal analysis. Riflebirds were found with highest frequency in mature rainforest sites. The 'core areas' of males (areas where they spent 95% of their time during the breeding season, and including all their known display posts) varied between 0.69 and 2.81 ha, and were in most cases composed primarily of mature rainforest. Within these areas, males were seen to defend only the immediate vicinity of display posts. Home ranges were considerably larger, as birds moved longer distances to reach fruiting trees, especially during the non-breeding season. Diet during the breeding season was heavily dominated by fruit, even though a large proportion of foraging time was spent seeking invertebrates in the rainforest understorey. Overall, this species exhibits a dispersed, non-territorial type of display dispersion, as do other birds of paradise with a mixed (fruit and invertebrates) diet.