Feeding Ecology of the Barn Owl, Tyto Alba, in Arid Southern Australia.

Abstract

In arid parts of Australia the barn owl appears to feed largely on rodents which form irruptions or plagues, i.e. undergo marked changes in abundance. Barn owls became common at the height of an irruption of house mice, Mus musculus, in western New South Wales, but were comparatively scarce after the mice decreased in numbers. There was some evidence that the owls' diet, determined by analysis of pellets, was more varied immediately after the numbers of mice decreased, but its major part still consisted of M. musculus. The mean number of prey units represented in each pellet rose during the irruption and then declined to the original level. At a variety of sites in arid New South Wales and South Australia, barn owls' diet consisted almost entirely of small mammals. The most common prey species were rodents that fluctuate widely in abundance, and the mean amount of prey per pellet differed greatly among the study sites. The feeding ecology of barn owls in arid Australian environments is essentially similar to that described for more mesic habitats; hence, a greatly increased variation in the abundance of mammalian prey has not led to an increase in breadth of food niche.

The Diet of the Rufous Owl Ninox Rufa Near Cooinda in the Northern Territory

“…Morton & Martin 1979). In the present study, prey were identified from skeletal material (mandibles, maxillae and pelvic girdle bones), fur (after Brunner & Coman 1974) and feathers.…”

Fossil mammals of Caladenia Cave, northern Swan Coastal Plain, south-western Australia

“…Tyto delicatula has been recorded on the northern Swan Coastal Plain (Storr et al 1978;Atlas of Living Australia 2013). The majority of the prey material is composed of rodents and small marsupials, most of which can be swallowed whole by owls (Morton and Martin 1979;Andrews 1990;McDowell and Medlin 2009).…”

The original mammal fauna of the Pilbara biogeographic region of north-western Australia

“…Obviously, there is an upper weight limit to the mammal species that it can catch and eat, at about the size of an adult rat; although it can prey upon juveniles of bandicoots and rat-kangaroos (Higgins 1999). A further bias is introduced by the nomadic behaviour of Barn Owls (Morton and Martin 1979). This is an adaptation to the population variations of native rodents.…”

“…Both the high relative abundance of the living rodents, and probably the owls' search images for these species, bias the resulting accumulations of remains toward disproportionately high rodent and low dasyurid relative abundances (e.g. Morton and Martin 1979;Baynes and Baird 1992;McDowell and Medlin 2009). This effect biases representation of species among remains in cave deposits in favour of rodents.…”