A study of the foraging ecology of the White-throated Treecreeper (Cormobates leucophaeus)

Abstract

We quantified the foraging ecology of the White-throated Treecreeper (Cormobates leucophaeus) in the Australian Capital Territory (ACT), south-eastern Australia, where it is the sole species of treecreeper present, and where a rough-barked eucalypt (Red Stringybark (Eucalyptus macrorhyncha)) and a smooth-barked eucalypt (Inland Scribbly Gum (Eucalyptus rossii)) are the dominant tree species. We examined relationships among foraging observations and variables including tree species, tree size, part of tree (substrate), time of day and month. We also quantified the kinds of foraging techniques used by the White-throated Treecreeper on different type and sizes of trees and at different times of the year. The White-throated Treecreeper more commonly foraged on Red Stringybark than on Inland Scribbly Gum. On Red Stringybark, the birds foraged more frequently on the trunk (above 4 m) and large branches than on other substrates. This trend was less marked on Inland Scribbly Gum, where dead branches were most often used for foraging. Foraging techniques that allowed rapid searching of each tree were those employed most commonly. Of these techniques, gleaning was most common (>50% of foraging time), but peering also was common. Drilling was most commonly performed on dead substrates. Foraging techniques employed by the White-throated Treecreeper changed significantly from morning to afternoon, with an increase in peering in afternoons. An increase in peering was observed for both sexes in April, but the magnitude of the increase was greater for females. White-throated Treecreepers in the ACT foraged more commonly on rough-barked eucalypts and exhibited less intraspecific resource partitioning between sexes than reported from other regions. Some of these differences may be related to contrasts in bird assemblages, particularly the absence of other bark-foraging species which may, in turn, reduce levels of intraspecific (gender-based) competition and resource partitioning. They also may be associated with differences in habitat attributes and resource availability between study areas.