Fine-scale habitat selection and space use by mountain goats (Oreamnos americanus): The Brownian bridge synoptic.

摘要

Current application of GPS telemetry in wildlife studies highlights the need for analytical methods to meet theoretical concerns during analysis of resource selection. I devised a new analysis technique for estimation of resource selection, the Brownian bridge synoptic model. Availability is based on the variance term from the existing Brownian bridge model, and maximum likelihood is used to estimate resource selection based on the existing synoptic model. The analysis separates the observed GPS data into triplets of observation and estimates probability of use at every other GPS location thereby. To test the model, I analyzed GPS data collected from free-ranging mountain goats Oreamnos americanus in the Cascade Mountains, Washington, where patterns of habitat selection were relatively unknown. I also conducted field reconnaissance and identified 8 vegetation communities across mountain goat home ranges: montane forest, subalpine forest, heather, huckleberry, east-side shrub, sparse meadow, dense meadow and talus. I linked the results of the field work to three LandSat 5TM scenes to create a map of vegetation communities. I used the vegetation map with the Brownian bridge synoptic model to evaluate patterns of habitat selection by mountain goats during late spring through early summer in response to the presence of potential forage items. Additionally, I used the Brownian bridge synoptic model, ordinary logistic regression, and the synoptic model to test patterns of habitat selection by mountain goats in response to backcountry trails. I used an information theoretic approach and compared the results of model selection at multiple scales approximating third and fourth orders of selection. I estimated habitat selection for individual animals and developed overall and sex specific population averages. Results showed topography as the primary determinant of selection by mountain goats with male mountain goats using steeper areas further from both escape terrain and trails than females. I found little evidence to suggest habitat selection by mountain goats was influenced by vegetation. Finally, I used the Brownian bridge synoptic model to address a management question concerning translocations and produced a resource selection function to evaluate potential release sites.