Spatial and temporal differences in the foraging behaviour of birds in a mixed eucalypt forest and woodland on the Southern Tablelands of New South Wales

Abstract

In Australia’s eucalypt forests and woodlands, co-habiting birds differ in the foraging manoeuvres or methods used to search for and take prey, the substrates and plants on which prey are found, and the heights at which foraging takes place. On the Southern Tablelands of New South Wales, eucalypt forest and woodland birds foraged on different substrates between study plots, seasons, and years. As a result, the proportions of foraging manoeuvres differed in space and time as different foraging methods were used to obtain food from different substrates. Of the 32 species tested for the summer of 1980/81, 24 foraged differently between one or more of the three plots studied. In winter, nine of 15 species on two plots foraged differently between plots. Differences in foraging were found between seasons and/or years for 20 species, including when data from individual plots were combined to test for differences in foraging between summer and winter. Of 70 comparisons of foraging behaviour for individual plots, that is, excluding combined plot data, 50 differed between seasons and/or years. Significant spatial and temporal differences in foraging were recorded for all foraging guilds. Bark and foliage foragers differed most frequently between pairs of plots in all seasons and years, with aerial foragers showing the fewest differences. Between seasons and years differences were greatest among ground-foragers and foliage-foragers where respectively 76% and 80% of intraspecies comparisons on individual plots differed. The differences were the result of temporal and spatial differences in the types and abundances of foraging substrates and the prey available to foraging birds. Each species has its own unique requirements and management targeted at one or a few species will disadvantage others. Consequently temporal and spatial habitat heterogeneity is necessary for the conservation of avian biodiversity.