INTERSPECIFIC COMPETITION IN AUSTRALIAN HONEYEATERS - DEPLETION OF COMMON RESOURCES

Many species of honeyeaters and other nectar‐feeding birds occur in most habitats in South Australia. They frequently feed on nectar of the same species of plants. A succession of species of plants provide nectar for birds throughout the year. Nectar is most abundant in winter and early spring and least abundant in summer and autumn. There is more nectar per flower and more flowers in winter and spring. Nectar is often depleted by honeyeaters, and sometimes other visitors (silvereyes, lorikeets and insects) between December and May. It is at times reduced to a level at which it is uneconomical for some species to exploit. There are seasonal movements of honeyeaters into areas of abundant nectar and out of these areas when nectar becomes scarce. Breeding coincides with peak abundance of nectar. Diversity of honeyeaters is probably maintained by an interaction of two types of competition, exploitation and interference. The larger species use the richest sources of nectar and aggressively exclude the smaller species (interference) whereas the smaller species can use poorer sources of nectar because their energy requirements are less (exploitation). Copyright © 1979, Wiley Blackwell. All rights reserved