Rodent-Prey Content in Long-Term Samples of Barn Owl (Tyto alba) Pellets from the Northwestern United States Reflects Local Agricultural Change

Rodent prey contained in two temporally distinct collections of Barn Owl (Tyto alba) pellets from the same roost in southeastern Washington state (USA) differ in terms of taxonomic abundances. Deer mice (Peromyscus maniculatus) dominate the fauna in the pellet sample deposited while much of the landscape was productive wheat field, and voles (Microtus spp.) are a distant second. The fauna in the pellet sample deposited after 20% of the surrounding landscape was placed in soil bank and converted to a grass non-producing field is dominated by voles with deer mice a close second. The coincident changes in local vegetation and in the rodent fauna are causally as well as temporally interrelated. Previous local studies have focused on the agricultural economics of coincident shifts in agricultural practices and rodent faunas. Results presented here indicate potential benefits to owl faunas of changes in agricultural practices and suggest that study of curated owl pellet faunas collected decades ago may reveal much about the long-term history of anthropogenic influences on rodent faunas.