RESOURCE PARTITIONING IN AN ISLAND COMMUNITY OF INSECTIVOROUS BIRDS DURING WINTER

Resource partitioning within an assemblage of seven species of insecti vorous birds inhabiting remnant Melaleuca woodland on Rottnest Island off the coast of Western Australia was studied during May-July 1993. F oraging behaviour, foraging height, foraging substrate and foraging pl ant associations of all species (and of both sexes in two species) wer e recorded for each month. These data were used to calculate overlaps in each foraging dimension and for all foraging dimensions combined. T he significance of total foraging overlap between species and sexes (d efined as overlap > 0.6) was low in May (only 14% of all total foragin g overlaps) but increased slightly in June and July (25 and 29% of all total foraging overlaps respectively). Foraging habits were associate d significantly both with bird species and month of observation, indic ating that foraging partition ing occurred and that its pattern varied temporally. The diversity of foraging habits displayed by each bird s pecies in each foraging dimension (determined by the Shannon-Wiener fu nction) varied widely, although a species which was a generalist in on e foraging dimension also tended to be a generalist in other foraging dimensions.