Graduation Date

Fall 2023

Document Type

Thesis

Program

Master of Science degree with a major in Natural Resources, option Wildlife

Committee Chair Name

Dr. Micaela Szykman Gunther

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Dr. Daniel Barton

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Dr. Andrew Kinziger

Third Committee Member Affiliation

HSU Faculty or Staff

Fourth Committee Member Name

Dr. Jared Duquette

Fourth Committee Member Affiliation

Community Member or Outside Professional

Subject Categories

Wildlife Management

Abstract

Black bear (Ursus americanus) populations have grown and recolonized historic range in California, and unharvested populations are currently poorly monitored by existing programs. In the Warner Mountains of northeast California, increasing issuance of bear depredation permits has underscored the importance of black bear population monitoring. To study population density, space-use, and demographics of this unharvested population, I established 10 non-invasive sampling clusters, comprising a 3 x 3 arrangement of 4-km2 grid-cells, across a 1,464 km2 study area and monitored hair snares over five 10-day sampling occasions in summer 2018. Fourteen microsatellite and two sex-specific genetic markers were used to distinguish individual identity and sex of hair snared bears and to develop spatially referenced capture histories. I used spatial capture-recapture (SCR) in R program oSCR to estimate population density and abundance and modeled heterogeneity in density across the study area. I evaluated the landscape covariates elevation, slope, canopy cover, NDVI, and distances to roads and streams. Additionally, I tested the effects of sex, ‘behavioral response’, and ‘day of survey’ on model detection parameters. The top SCR model included effects of behavioral response and day of survey on baseline detection probability and an effect of sex on baseline detection probability’ (p0) and spatial scale parameter (σ). The top model further showed density was positively influenced by percent canopy cover and slope. Average density of black bears in the Warner Mountains was estimated to be 0.11 bears per km2 representing 104 females and 121 males (N = 225 bears). Chi-squared testing indicated that the proportion of females to males did not differ from 1:1 indicating that the Warner Mountain population may be in a post-recolonization state. Lastly, sex specific estimates of σ corresponded with female and male home range estimates of 85 km2 (range 51–140 km2) and 329 km2 (188–575 km2), respectively. Estimated population parameters for black bears in the Warner Mountains are most similar to comparably arid environments (e.g., eastern slopes of the Sierra Nevada and Cascade ranges of the Pacific northwest), demonstrating support for a pattern of density and space-use differences relative to regional habitat and climatic characteristics. Identifying how this high-desert region of Northeastern California fits into observed patterns of density and space-use across regions of California is an important first step toward considering how this black bear population fits into statewide bear management efforts.

Citation Style

The Journal of Wildlife Management

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