Foraging behaviour of nesting Striated Thornbills Acanthiza lineata : is sex important?

It is common for male and female birds to differ in foraging behaviour. However, in more than 50% of species, males and females are alike in size and plumage and cannot be sexed in the field. Thus, there are few data on the foraging behaviour of monomorphic species. This paper compares the foraging behaviour during the nesting season of colour banded male and female Striated Thornbills Acanthiza lineata, a monomorphic species. The two sexes differed in foraging heights, tree species selection, and foraging substrates, but not prey-attack behaviour. The differences reduce competition between males and females, increasing the resources available to a nesting pair, and are an example of optimal foraging.