Publication Date
Fall 2025
Degree Type
Thesis
Degree Name
Master of Science (MS)
Department
Environmental Studies
Advisor
Rachel O'Malley; Lynne Trulio; Richard Kos
Abstract
Beavers (Castor canadensis), keystone ecosystem engineers, were once widespread in North America before being hunted to near extinction in the 1830s. Beaver reintroduction now offers a nature-based way to restore freshwater systems and buffer against climate change. The Beaver Restoration Assessment Tool (BRAT), which ranks reintroduction sites by dam-building potential, has not been evaluated in coastal California’s small, rain-fed watersheds. This study developed a novel spatial model based on the California Department of Fish and Wildlife (CDFW) Beaver Restoration Project Proposal and tested three levels of weighted human conflict. Using a social-ecological approach, the model integrates human conflict with ecological suitability factors. This study contrasted suitability predictions of each of these models across 14,497 coastal California Discrete Geographic Objects (DGOs) and 21 Methow field samples. The study also compared BRAT to 67 iNaturalist sightings to check habitat use by extant beavers. The high conflict model and BRAT underestimate suitable habitat compared to low-conflict models. Field data matched more closely to BRAT and the high-conflict model predictions. Sightings data showed more lower-scored BRAT habitats are occupied than expected. Results suggest that BRAT and field sampling may overestimate human conflict potential and underestimate viable sites for reintroduction or natural dispersal.
Recommended Citation
McMillan, Ann Marie, "How To Bring Back Beavers in Coastal California? A Novel Model, Field Data, and Inaturalist Suggest the Beaver Restoration Assessment Tool (Brat) May Overemphasize Potential for Human Conflict" (2025). Master's Theses. 5712.
DOI: https://doi.org/10.31979/etd.g63f-ykkv
https://scholarworks.sjsu.edu/etd_theses/5712
