An Overlooked Cost for the Velvety Plumage of Owls: Entanglement in Adhesive Vegetation

Abstract

We used data collected during 1995– 2007 at the only Wildlife Rehabilitation Center on Tenerife Island (Canary Islands) to quantify entangle- ment mortality of owls. At least 66 of 1,206 Long- eared (Asio otus) and 5 of 231 Barn (Tyto alba) owls admitted to the Wildlife Rehabilitation Center were en- tangled in burr bristlegrass (Setaria adhaerens). Twelve (18.2%) of the 66 Long-eared Owls died as a result of entanglement while one of five Barn Owls died. A higher incidence of entanglement occurred during summer, coinciding with seed-head ripening and dispersing recently-fledged owls. Velvety plumage may be an important cost for owls, and responsible for owls acting as seed dispersers