Graduation Date

Spring 2023

Document Type



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

Committee Chair Name

Dr. Richard Brown

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Dr. Greta Wengert

Second Committee Member Affiliation

Community Member or Outside Professional

Third Committee Member Name

Dr. Matthew Johnson

Third Committee Member Affiliation

HSU Faculty or Staff


Trespass grows, Trespass cannabis grows, Cannabis, Illicit cultivation, Gray fox, Habitat selection, Habitat use, Behavior, Northern California, Public lands, Mesocarnivore, Pesticides, Autocorrelated kernel density estimate, Resource selection function, national forests

Subject Categories



Trespass cannabis grow sites, otherwise known as illegal cultivation sites on public lands, are extremely hazardous to the environment and can severely impact wildlife movement and behavior. Trespass grow sites are dangerous to wildlife as they negatively impact the quality of habitat and wildlife behavior through habitat modification, pesticide use, discarding of trash, and poaching on national forests. I researched gray fox habitat selection and habitat use at six different grow sites in the Klamath National Forest and Shasta-Trinity National Forest in northwestern California. I deployed GPS collars on three gray foxes at two of those grow sites and three gray foxes at two reference sites between September 2020 and April 2021. I used autocorrelated kernel density estimates and resource-selection functions, using generalized linear models, to evaluate gray fox habitat selection and found that two of the three gray foxes selected trespass grow sites when grow sites were found within their home ranges. I evaluated the combined data of all six collared foxes in regard to environmental characteristics and found that foxes prefer areas with a greater aspect, specifically those facing south, southwest, and west. I deployed eighty-eight game cameras across six trespass grow sites to collect photo and video media for 22 months. I used the Shapiro Wilks Normality test and the Mann Whitney U test to compare gray fox behavior across different grow site features. There were a higher number of detections of gray foxes at process areas, camp sites, toxicant piles, and trash pits. Locomotion behavior was observed at similar levels across all site features. Vigilant behaviors were most observed at toxicant piles, camp sites, trails, and cultivation plots. Marking behaviors were most common at process areas, trash pits, and toxicant piles. The most recorded behavior was locomotion, followed by vigilance, scent marking, and then feeding, with no documented behaviors of resting. Proportionally more foxes were recorded at camp sites, toxicant piles, trash pits, and process areas than in cultivation plots or along trails, which signifies that gray foxes utilize areas hypothesized as more attractive within the grow site. This research shows that foxes use trespass grows, though future researchers are encouraged to include a larger sample size collared gray foxes and of the cultivation plot and trail locations. Resource agencies must prioritize elimination and reclamation of these sites. Otherwise, wildlife will continue to suffer direct and indirect effects as they utilize the trespass grow sites present in their home ranges.

Citation Style

Jones, H. R., Wengert, G. M., Brown, R. N., and M. D. Johnson. 2023. Habitat selection and habitat use of gray foxes (Urocyon cinereoargenteus) on trespass cannabis grows. M.S. Thesis, California Polytechnic University, Humboldt, California.


Thesis/Project Location


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