Abstract
The authors collected 14 pellets from 6 long-eared owls, Asio otus, wintering in a riparian zone on the Tama River in the Tokyo metropolitan area from December 2010 to January 2011. The winter roost of the owls is now surrounded by sports grounds and urban sprawl. Two Microtus montebelli, 21 Mus musculus, 2 Rattus norvegicus, 6 Pipistrellus abramus and unknown bird species were identified from the pellets, demonstrating that the owls preyed primarily on small mammals typical of urban areas. This is also the first record of P. abramus being preyed on by A. otus wintering in the Kanto area.
