Relative importance of plague rodents and dasyurids as prey of barn owls in central Australia

We examined the diet of the barn owl in three bioregions of arid Northern Territory; two in upland areas, the other on the Barkly Tableland. Owls from the MacDonnell and Petermann Ranges fed predominantly on rodents. At both sites, Mus musculus was the dominant prey both in terms of frequency and prey units, with Pseudomys hermannsburgensis an important secondary item. Notomys alexis was an important secondary item in the MacDonnell Ranges. These results support previous research in highlighting the importance of plague rodents in the diet of barn owls in arid Australia. In contrast to the samples from the upland sites, the Barkly Tableland sample was composed mostly of the dasyurid marsupial Sminthopsis macroura, with only one rodent captured. The absence of the long-haired rat, Rattus villosissimus, from the sample, despite the species being a favoured prey item of the barn owl that undergoes population irruptions at the collection site, suggests that the sample was collected during a non-plague period. Our study is the first to record a marsupial species as the major prey of the barn owl. This finding suggests that barn owls can switch to other prey when populations of rodents crash.