The avifauna of severely fragmented, Buloke Allocasuarina luehmanni woodland in western Victoria, Australia

Abstract

Buloke Allocasuarina luehmanni woodland is an endangered habitat type that was once widespread in southern Australia but now is restricted to a series of remnants, many of which are located in the Wimmera region of western Victoria. The bird communities inhabiting 27 remnants were sampled on transects of 1.0 ha at 6-week intervals over one year. Ninety-five species of birds were observed in Buloke woodlands, of which 66 species were recorded during transect counts. The total species richness, the richness of groups of birds based on their habitat use, and the composition of assemblages on transects, were examined in a series of analyses with respect to habitat type (which probably reflects "quality"), remnant area, shape, isolation and geographic location. There was little evidence for attributes of remnants significantly influencing species richness per transect, but the composition of avifaunal assemblages varied in relation to habitat type, size and geographic location. The Buloke woodlands supported a diverse assemblage, including numerous species believed to be experiencing a regional decline in southern Australia. The composition of the Buloke assemblage has similarities to those of dry eucalypt woodlands across the plains of central Victoria, but elements contributing to a distinctive avifauna include species associated with semi-arid and mallee environments, and a high frequency of occurrence of a group of small insectivores (thornbills, robins) that favour dry She-oak and Callitris woodlands. A likely reason for the rich representation of small insectivores in woodland stands, even in small degraded remnants grazed by stock, was the scarcity of the Noisy Miner Manorina melanocephala that are often common in eucalypt remnants and known to aggressively exclude other species. The results of this study add weight to the recommendation that protection and restoration of Buloke woodlands is a priority for conservation in the Wimmera bioregion of Victoria.