Graduation Date

Spring 2024

Document Type



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

Committee Chair Name

Matthew D. Johnson

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Daniel Barton

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Susan Marshall

Third Committee Member Affiliation

HSU Faculty or Staff

Fourth Committee Member Name

Elizabeth Porzig

Fourth Committee Member Affiliation

Community Member or Outside Professional


Grassland birds, Native perennial, Sparrows, California rangelands, Coastal prairie, Habitat quality, Physiological indicators, H:L ratio

Subject Categories



Prescribed grazing management can have myriad effects on wildlife, with low to moderate grazing being associated with an increased abundance of some grassland birds. Specifically, Grasshopper Sparrow (Ammodramus savannarum) and Savannah Sparrow (Passerculus sandwichensis) abundance have been shown to be positively associated with both grazing and a higher percentage of native plant cover. However, measures of abundance provide an incomplete assessment of habitat quality for birds. Physiological and morphological measurements can help indicate environmental stress in individual birds, which reveals more information about habitat quality. We measured body condition and heterophil:lymphocyte ratios to gauge avian stress response to different vegetational functional groups and abiotic habitat features within grassland sparrow territories along the California coast. Grasshopper Sparrows showed less stress in areas with higher perennial grass cover, lower native plant cover, and flatter slopes, while Savannah Sparrows experienced less stress in areas with lower perennial grass cover and higher native plant cover. Both species were under lower levels of stress in areas with lower shrub cover, lower annual grass cover, and lower variation in vegetation height. Grassland management that attempts to mitigate annual grass proliferation and shrub encroachment can have a potentially positive effect on these two grassland birds.

Citation Style



Thesis/Project Location


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