Ecological Patterns in a Terrestrial Bird Community in Arid North-Western New South Wales

Abstract

Ecological patterns were investigated in a bird community in a variable and unpredictable arid environment. About half the species recorded were resident, one third nomadic and the remainder spring-summer or winter migrants. The different strategies, residency, nomadism and migration, were related to other parameters including population dynamics, habitat selection, foraging, nesting, drinking and aggressive behaviour. Over four years the composition of the bird community changed continually. Drought had a deleterious effect on the avifauna, but its effect differed between species. Run-on habitats (creeklines) supported denser populations and more species of birds than run-off habitats. The composition of the creekline avifauna reflected a gradient from wetter, eucalypt-fringed creeklines to drier, non-eucalypt creeklines. Seven feeding guilds were identified. The main feeding substrate was the ground, followed by foliage and air. Perennial plants provided most foliage, flower and bark feeding substrates. Residents tended to be generalised or opportunistic feeders. The greater mobility of nomads allowed dietary specialisation. ... Several factors, including individualistic responses of species to temporal and spatial variability, the aggression of the White-plumed Honeyeater, positive associations between species in mixed-species flocks, arid predation, play a part in determining the structure of the bird community. The implications for the conservation of arid zone birds are discussed.