Winter Movements and Range Use of Radio-marked Mexican Spotted Owls: An Evaluation of Current Management Recommendations

Abstract

We summarized existing knowledge on winter movements and range and habitat use of radio-marked Mexican spotted owls. In light of that information, we evaluated the adequacy of current management guidelines. Seasonal movement or "migration" appears to be a regular feature of the winter ecology of Mexican spotted owls. Most radio-marked owls studied were resident in and around their breeding areas year-round, but some owls migrated in most populations studied. Owls that were year-round residents generally expanded their home range during the non-breeding season, and many exhibited spatial shifts in area used. Despite these shifts, however, overlap between seasonal ranges was relatively great for most individuals. For these owls, current guidelines aimed at conserving nesting habitat also would conserve areas used during the non-breeding season. Additional recovery plan guidelines aimed at protecting habitats with structure similar to nesting areas should be useful in protecting other areas used by resident owls expanding their range during winter. In contrast, migrating owls typically moved to lower elevations and into open habitats not used by breeding owls. Current guidelines do not protect these habitats. However, we currently have (1) no evidence that such habitats are limiting, (2) no evidence that special protection is necessary in these areas and/or habitats, (3) little information on which to base such protective measures if they are necessary, and (4) no objective way to identify important wintering areas used by migrating owls. Until better information is available, we see no compelling reason to develop specific guidelines for protection of wintering areas.

Citation

Ganey, Joseph L.; Block, William M. 2005. Winter Movements and Range Use of Radio-marked Mexican Spotted Owls: An Evaluation of Current Management Recommendations. Gen. Tech. Rep. RMRS-GTR-148. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 9 p.