Graduation Date
Summer 2026
Document Type
Thesis
Program
Master of Science degree with a major in Natural Resources, option Wildlife
Committee Chair Name
Matthew Johnson
Committee Chair Affiliation
Cal Poly Humboldt Faculty or Staff
Second Committee Member Name
Ho Yi Wan
Second Committee Member Affiliation
Community Member or Outside Professional
Third Committee Member Name
Jeffrey Dunk
Third Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Fourth Committee Member Name
Christopher Briggs
Fourth Committee Member Affiliation
Community Member or Outside Professional
Keywords
Adaptive habitat selection, Swainson's hawk, Density-dependence, Habitat quality
Subject Categories
Wildlife
Abstract
Adaptive habitat selection theory predicts that individuals preferentially select habitats that maximize or improve their fitness. However, patterns of habitat preferences may dampen with increasing population density and become decoupled from habitat quality when environmental conditions change. Such dynamics may be especially important in long-lived territorial species that exhibit site fidelity. One of the longest running raptor studies in North America has tracked an increasing population of breeding Swainson’s Hawks (Buteo swainsoni) in Butte Valley, California since 1985, where agricultural practices have shifted over the decades, providing an ideal system for studying these processes. Using nest records from 1985-2024, I examined nest site selection and reproductive performance over time and as a function of land cover composition. Swainson’s Hawks consistently selected territories associated with alfalfa (Medicago sativa) and grasslands while avoiding habitats dominated by juniper woodland. However, habitat selection was density dependent: as breeding density increased, habitat preferences became progressively weaker. Despite clear patterns of habitat selection, preferred habitats were only weakly associated with nest success and productivity. Row crops and bare soil were neither selected nor avoided despite being negatively associated with reproduction. These results reveal a limited correspondence between habitat selection and habitat quality. I suggest that density-dependent breeding habitat selection, combined with strong territory fidelity and a dynamic agricultural landscape, may weaken the relationship between habitat selection and fitness. More broadly, the results highlight how behavioral responses that were once adaptive may become less so as human-mediated environmental conditions change through time.
Citation Style
Journal of Raptor Research
Recommended Citation
Meisman, Elizabeth, "Testing adaptive habitat selection in breeding Swainson's hawks (Buteo swainsoni)" (2026). Cal Poly Humboldt theses and projects. 2605.
https://digitalcommons.humboldt.edu/etd/2605