HOME RANGES AND SPATIAL ORGANIZATION OF WESTERN SCREECH-OWLS IN SOUTHERN BRITISH COLUMBIA

摘要

The macfarlanei subspecies of the Western Screech-owl (Megascops kennicottii) resides in the dry southern interior of British Columbia and is federally endangered in Canada. We captured and radio-tagged 11 adult screech-owls (6M, 5F) between July 2005 and January 2008 to collect ecological information needed to direct effective conservation. We collected point radiolocations from tagged owls to estimate seasonal and year-round home ranges with the 95% isopleth of the utilization distribution calculated using fixed kernel methods. Screech-owl home ranges averaged 64.5 ha (s = 10.6, n = 5), with no substantial difference in size between males and females. Owls used considerably smaller areas during the breeding season (x = 20.4 ha, s = 15.3, n = 7) than the non-breeding season (x = 88.6 ha, s = 44.5, n = 6). During the breeding season, males and females of a single pair overlapped extensively, whereas outside the breeding season very little overlap occurred within pairs. We did not detect overlap between neighbouring pairs. Home ranges of Western Screech-owls were highly associated with riparian forests; most screech-owls had ≥10 ha of riparian forested habitats within their home ranges. These results have implications for habitat conservation for this endangered species.