Demography, home range, and habitat selection of northern spotted owls in the Ashland Watershed Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/n009w4359

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  • Northern Spotted Owls (Strix occidentalis caurina) inhabit productive forests that historically supported frequent, large, variable-severity fires in the Klamath province of southwestern Oregon occur in complex. The potential for high-severity wildfire remains high throughout this region, so remaining spotted owl habitat is at risk. An adaptive management approach to fire management and owl recovery in these forests is being advocated under the Final Recovery Plan for the Northern Spotted Owl. However, it is currently unclear what short- or long-term effects these fuels reduction treatments will have on spotted owl populations. Proposed forest thinning treatments planned for the Ashland Watershed in southwestern Oregon provide an unprecedented opportunity to study the effects of thinning on spotted owl ecology. My objectives were to determine 1) monthly survival rates and 2) home range size of spotted owls in relation to habitat characteristics, and 3) owl habitat selection. Data were collected prior to forest manipulations and will serve as a baseline for comparison with post-thinning data. Survival, home range size and habitat selection for 15 Northern spotted owls were monitored using radio telemetry in the Ashland Watershed and surrounding area from September 2006 to October 2008. A remote-sensed vegetation map of the study area was used to characterize habitat classes and configuration. Estimates of monthly survival were generated in relation to habitat characteristics using program MARK. Monthly survival was positively correlated with the number of late forest patches within the individual home range and negatively correlated with the mean nearest neighbor of late forest patches. Annual home range size varied from 189 to 894 ha. Annual home range size increased with increased amounts of edge and decreased with increased amounts of intermediate aged-forest. The mean breeding season home range size was 491 ha and was larger than mean non-breeding season home ranges. Home range size increased with the addition of hard edge, and amount of old and mature forest combined. The mean size for annual core areas was 77 ha. The best predictor of both non-breeding home range size and core area size was hard edge. While home range size was positively related to the amount of hard edge within non-breeding home range in a linear fashion, core area size increased with increasing amounts of hard edge, but only up to a threshold point, where further increases in edge did not increase core area size. Logistic regression was used to model habitat selection of owls in relation to forest characteristics. Individual owls exhibited different preferences in selecting habitat for foraging and roosting. Overall, owls selected for habitat that was closer to streams and further away from edge. Old forest did not significantly influence selection, but mature forest was positively associated with annual and winter habitat selection for several individual owls. Intermediate forests and non-habitat were only weakly associated with spotted owl habitat selection.
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  • description.provenance : Approved for entry into archive by Julie Kurtz(julie.kurtz@oregonstate.edu) on 2009-07-22T17:55:13Z (GMT) No. of bitstreams: 1 Schilling_Thesis.pdf: 3200069 bytes, checksum: 80f2ceb064ca5181f7d3acaf9bcb1058 (MD5)
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  • description.provenance : Submitted by Jason Schilling (jason.schilling@oregonstate.edu) on 2009-07-15T00:28:37Z No. of bitstreams: 1 Schilling_Thesis.pdf: 3200069 bytes, checksum: 80f2ceb064ca5181f7d3acaf9bcb1058 (MD5)
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