Graduation Date
Fall 2023
Document Type
Thesis
Program
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. Barbara Clucas
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Ho Yi Wan
Third Committee Member Affiliation
HSU Faculty or Staff
Subject Categories
Wildlife Management
Abstract
Human disturbances can negatively affect wildlife by causing stress, altering behavior, or even impacting populations through changes in survival or productivity. Colonial-nesting seabirds are of particular concern due to population declines and their gregarious and conspicuous nature, which may attract human visitors. However, the effects of nearby human activities, though frequently negative, could be neutral or even positive through phenomena like habituation to human activities or subsidization by human-supplied food sources. In this observational study, I evaluated relative support for three hypotheses which may explain how Western Gulls are impacted by human activity: disturbance, habituation, and subsidization. I investigated this by comparing reproductive success and behaviors at two colonies of Western Gulls (Larus occidentalis) with different exposure to human activity. I estimated nest and chick survival for 110 nests located in northwestern California from May-September 2022, and quantified parental attendance for a subset of those nests. I found no difference in either measure of reproductive success between the two colonies, despite a clear difference in the frequency of potential disturbances. However, parental attendance was substantially higher at the high disturbance-risk colony. These findings may indicate that birds at the high-risk colony are habituated to or subsidized by human activities, and that efforts to reduce disturbance by limiting human activity near islands may be ill-suited for this area.
Citation Style
Journal of Wildlife Management
Recommended Citation
Bowen, Lilamarie 'Asta, "Western gulls’ (Larus occidentalis) reproductive and behavioral responses to human disturbance" (2023). Cal Poly Humboldt theses and projects. 714.
https://digitalcommons.humboldt.edu/etd/714