TEMPORAL CHANGES IN THE FORAGING BEHAVIOR OF INSECTIVOROUS BIRDS IN A SCLEROPHYLL FOREST IN TASMANIA

Seasonal changes in the foraging behaviour of 13 insectivorous bird species were investigated in a sclerophyll forest in north-eastern Tasmania between April 1989 and May 1990. Six guilds (ground gleaners, ground pouncers, foliage gleaners, a foliage snatcher, bark probers and a hawker) were identified in the winter period (April to September). In the summer period (October to March), the same guilds were identified, except that the winter ground pouncing and foliage snatching guilds were replaced by a more diffuse general foraging guild. Three of the four winter ground foraging species expanded their range of foraging substrates and methods during summer. The fourth winter ground foraging species (White-browed Scrubwren) continued to forage predominantly on the ground during summer but expanded the range of methods used when foraging on this substrate. The two bark foraging species showed changes in the types of bark substrates,used throughout the year. The observed seasonal changes in foraging behaviour resulted in an increase in community foraging overlap and in the overlap between guilds during the summer. The seasonal changes in foraging behaviour observed in this study suggest that it is important that those managing the forest, retain a diversity of both foraging substrates and habitat types, to sustain the normal foraging activities of the bird community.