Graduation Date

Fall 2023

Document Type

Thesis

Program

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

Committee Chair Name

Micaela Szykman Gunther

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Erin Zulliger

Second Committee Member Affiliation

Community Member or Outside Professional

Third Committee Member Name

Brett Furnas

Third Committee Member Affiliation

Community Member or Outside Professional

Fourth Committee Member Name

Ho Yi Wan

Fourth Committee Member Affiliation

HSU Faculty or Staff

Subject Categories

Wildlife Management

Abstract

Increasing fire size and severity in the western United States causes changes to ecosystems, species’ habitat use, and interspecific interactions. Wide-ranging carnivore and ungulate mammalian species and their interactions may be influenced by an increase in fire activity in northern California. Depending on the fire characteristics, ungulates may benefit from burned habitat due to an increase in forage availability, while carnivore species may be differentially impacted, but ultimately driven by bottom-up processes from a shift in prey availability. I used a three-step approach to estimate the single-species occupancy of four large mammal species: mountain lion (Puma concolor), coyote (Canis latrans), elk (Cervus canadensis subspp.), and black-tailed deer (Odocoileus hemionus columbianus) in the Klamath Mountains bioregion of northern California. First, I tested the optimal detection probability variables. Next, I performed a scale-optimization approach for two environmental variables to explain occupancy probability: time since fire and normalized difference vegetation index (NDVI). Lastly, I tested the full-single species models. Using the components of the most predictive single-species models, I then utilized multi-species models to test the co-occurrence between all species pairs. I found that species exhibited differences in the optimal spatial scales, which were largest for mountain lions (4,000-m radii), intermediate for coyotes (500-m to 2,000-m radii) and elk (30-m to 500-m radii), and smallest for deer (125-m radii). Environmental variables in the top single-species occupancy models and their effect varied by species. The species’ relationships with time since fire varied, but occupancy probability increased with longer time since fire for coyotes and decreased with longer time since fire for elk. The relationship with time since fire was slightly positive, but non-significant for both mountain lions and deer. Both mountain lion and elk occupancy probability increased with higher NDVI values, but there was the opposite relationship for coyotes. Finally, I found evidence of co-occurrence between one species pair: coyote and elk. Overall, I found species had varying scales of selection and associations with time since fire. As fire activity increases in the western United States, understanding the impacts of fire on occurrence and interspecific interactions can inform species and habitat management plans.

Citation Style

JWM

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