CONSIDERING CONTROL OF INVASIVE BARRED OWLS TO BENEFIT CALIFORNIA SPOTTED OWLS: POSSIBLE JUSTIFICATION AND DRAFT METHODS

Authors

Kent B. Livezey, U.S. Fish and Wildlife Service, Western Washington Fish and Wildlife Office, Lacey, Washington, USA
Richard M. Engeman, National Wildlife Research Center, Fort Collins, Colorado, USAFollow
Dennis F. Rock, National Council for Air and Stream Improvement, Amboy, Washington, USA
Donald A. Yasuda, U.S. Forest Service, McClellan, California, USA

Date of this Version

8-1-2007

Comments

Published in: Witmer, G. W., W. C. Pitt, and K. A. Fagerstone, editors. 2007. Managing vertebrate invasive species: proceedings of an international symposium. USDA/APHIS Wildlife Services, National Wildlife Research Center, Fort Collins, Colorado, USA. Also available online at http://www.aphis.usda.gov/wildlife_damage/nwrc/symposia/invasive_symposium/nwrc_TOC_index.shtml

Abstract

Invasive, but native to North America, barred owls (Strix varia) are negatively affecting site occupancy, reproduction, and survival of federally threatened northern spotted owls (Strix occidentalis caurina), thereby confounding the land-based conservation strategy for northern spotted owls. Barred owls are moving southward into the range of non-federally listed California spotted owls (S. o. occidentalis), but are not, at this time or in the foreseeable future, a threat to the California spotted owl population. We recommend consideration of barred owl control in the northern Sierra Nevada Mountains, while barred owl numbers are low enough to efficiently eliminate the possibility that they negatively affect California spotted owls outside of the foreseeable future.