Impacts of logging, fire and grazing regimes on bird species assemblages of the Pilliga woodlands of New South Wales

Abstract

We investigated the composition and distribution of bird assemblages in the continuous Pilliga woodlands of north-west New South Wales in relation to floristic assemblages and disturbance (logging, fire and grazing) patterns. Box-ironbark woodlands contained high densities of White Cypress Pine Callitris glaucophylla and Narrow-leaved Ironbark Eucalyptus crebra, had a sparse, depauperate understorey, and were associated with frequent, intense logging and infrequent fires (due to fire exclusion and the use of grazing for fuel reduction). Box-ironbark woodlands were characterized by high frequencies of 12 bird species that occurred throughout the Pilliga and low frequencies of many other species. Blakely's Red Gum E. blakelyi woodlands typical of creeks and Broad-leaved Ironbark E. fibrosa woodlands typical of poor soils contained lower densities or smaller trees of C. glaucophylla and E. crebra, had a moderately dense, diverse understorey, and were associated with infrequent low-intensity logging and moderately frequent wildfire. Bird species assemblages of Broad-leaved Ironbark woodlands were similar to those of box-ironbark woodlands. Blakely's Red Gum woodlands were characterized by 36 bird species that were virtually absent from box-ironbark and Broad-leaved Ironbark woodlands, including 10 threatened and declining species. The 10 are among 48 woodland species that are known or thought to be declining and that are dependent on woodlands with mature trees and grassy or patchy grass/shrub understorey. We conclude that these species have declined in the Pilliga and will continue to decline under existing disturbance regimes, particularly in box-ironbark woodlands. We suggest adaptive management strategies for maintaining and rehabilitating their habitats.