Seasonal and landscape differencesin the foraging behaviour of the Rufous Treecreeper Climacteris rufa

Abstract

The insectivorous Rufous Treecreeper Climacteris rufa has declined in abundance in the agricultural regions of southwestern Australia. Examining its foraging behaviour is fundamental to identifying important foraging resources and how landscape change (e.g., fragmentation and disturbance) may affect foraging effectiveness. We studied seasonal and landscape differences in the foraging behaviour of the treecreeper in the wheatbelt of Western Australia. Foraging data were collected in autumn and winter in a large, unfragmented landscape and in a highly modified agricultural landscape (winter only) with grazed and ungrazed woodland patches. The ground layer was the most common foraging location used by the species, although there were seasonal differences in foraging behaviour in the unfragmented landscape. In autumn, treecreepers foraged primarily on trees (56% of observations) with a shift to mostly ground foraging in winter (72-74%). The species also preferentially foraged on larger trees. Foraging behaviour differed between the two landscapes within the same season. Treecreepers foraged less on the ground in the agricultural landscape (52%), but this difference is attributed mainly to the low percentage of ground foraging in ungrazed (43%) compared to grazed (60%) patches. In winter and early spring, the ground layer is an important foraging substrate for the Rufous Treecreeper and other woodland birds. Changes to the ground layer and associated invertebrate communities through habitat disturbance (e.g., weed invasion) may be detrimental to the foraging effectiveness of ground-foraging insectivores. This is a potential contributing factor to the decline of these species in the agricultural regions of southern Australia.