Relationships between bird species and characteristics of woodland remnants in central New South Wales

Abstract

This study investigated relationships between birds and characteristics of woodland remnants in the central wheat/sheep belt of New South Wales, in order to provide information for conservation management of woodland birds and their habitats in this region. Birds were surveyed in standard area plots in 36 woodland remnants, which ranged from 1 to 1 376 hectares in size, in the central Lachlan catchment in the wheat/sheep belt of New South Wales. Habitat (e.g., shrub cover) and landscape (measures of isolation) characteristics of the remnants were recorded also. Presence/absence occurrences of 20 or more bird species, mostly woodland birds, were positively related to remnant area, shrub cover, number of shrub species, pine cover, fallen logs and branches, and number of remnants within two and five kilometres of the survey remnant. Species of birds that are habitat generalists showed negative or no relationships with these habitat and landscape variables. Richness of all bird species was positively related to remnant area and shrub cover. Number of woodland bird species was positively related to remnant area, shrub cover and tree hollows. Lower species diversities in smaller remnants were most likely caused by lower chances of survival or of successful breeding in small remnants, effects of isolation on the ability of birds to recolonize smaller remnants, small remnants being of insufficient area for some species to form territories, and generally poor habitat quality in small remnants. Retention, management and enhancement of woodland remnants 10 to 20 hectares or larger in size with good understorey cover are necessary for the future viability of woodland birds in the wheat/sheep belt of New South Wales.