Graduation Date

Summer 2019

Document Type



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

Committee Chair Name

Dr. Daniel Barton

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Dr. William Bean

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Mark Colwell

Third Committee Member Affiliation

HSU Faculty or Staff

Subject Categories



Rocky coastlines incur high impacts from human use, but these places are also essential habitat for marine wildlife including seabirds and pinnipeds (seals and sea lions). Marine wildlife use coastal rocks to breed, rest, and engage in social interaction and exhibit different habitat use during the breeding and non-breeding season. Peak timing of human use occurs in spring summer, coinciding with breeding seasons for colonial seabirds and gregarious pinnipeds. The high potential of spatial and temporal overlap between human and seabird use of rocky coastlines could lead to high risk of disturbance events. I investigated the relative risk of disturbance to 8 species of marine wildlife including Brandt’s Cormorant (Phalacrocorax penicillatus), Double-crested Cormorant (Phalacrocorax auritus), Pelagic Cormorant (Phalacrocorax pelagicus), Western Gull (Larus occidentalis), Black Oystercatcher (Haematopus bachmani), Pacific Harbor Seal (Phoca vitulina), California Sea Lion (Zalophus californianus), and Steller Sea Lion (Eumetopias jubatus) from varying types of human use to inform science-based cooperative management in areas where humans and wildlife overlap. I estimated space sharing between marine wildlife and human use activities using spatial overlap methods, specifically using the volume of intersection (VI) test statistic in Trinidad, California.

Results of this project identified areas of varying levels of spatial overlap between seabirds, pinnipeds and varying types of human use (including consumptive and motorized activities). The species exhibiting the most space sharing with human use were Western Gulls with a VI score of .741 ± .058, while the least amount of space sharing with human use were Steller Sea Lions with a VI score of .0283 ± .0016. Human use also varied among the study area, with more consumptive and motorized activity in the northern study extent, and more non-consumptive (recreational) use and non-motorized activity in the southern study extent. This project provided an assessment of the volume of intersection index as a spatial tool for identifying specific user groups for education, disturbance risk assessment, outreach and enforcement for marine wildlife protection.

Citation Style

The Journal of Wildlife Management


Thesis/Project Location