Nectarivorous bird assemblages in Box-Ironbark woodlands in the Capertee Valley, New South Wales

Abstract

Spatial and temporal variability in nectarivorous bird assemblages was studied at 16 sites over four years in the Capertee Valley, New South Wales. We investigated differences in assemblages among years, seasons and habitats, and predictability in the nectarivorous bird community in space and time. One rare species, the Regent Honeyeater, was investigated more closely to determine whether it was consistently associated with particular bird species or flowering plants.

Nectarivorous birds showed no predictable variation in time (month to month) and numbers fluctuated erratically at all sites and over the valley, when all sites were combined. Differences in bird assemblages were recorded between warm and cool seasons in some years but this was not consistent across all years. Some habitat differences were consistently found. The drier woodlands on slopes were characterised by abundant Yellow-faced Honeyeaters, while the valley habitats (cleared, riparian and cleared with large mature trees) were associated with abundant White-plumed Honeyeaters. However, many species were common to all habitats and sites showed low similarity in composition within a habitat. Honeyeaters were not more abundant at sites with flowers. Similarly, Regent Honeyeaters were not consistently associated with sites with flowering trees, suggesting that other resources such as insects may influence spatial movements of nectarivorous birds. An increase in the presence of White-plumed Honeyeaters, Little Lorikeets and Noisy Friarbirds, and a decrease in Noisy Miners and Fuscous Honeyeaters characterised the bird assemblage when Regent Honeyeaters were present.

These results suggest that landscape-level conservation is important as nectarivorous birds appear to move among a range of sites and habitats in an unpredictable manner, including areas that are largely cleared of understorey. Although the use of riparian habitats by nectarivores indicates its high conservation value, the maintenance of a few specific sites in the valley is unlikely to maintain nectarivorous bird numbers.