Graduation Date
Spring 2024
Document Type
Thesis
Program
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
Keywords
Grassland birds, Native perennial, Sparrows, California rangelands, Coastal prairie, Habitat quality, Physiological indicators, H:L ratio
Subject Categories
Wildlife
Abstract
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
APA
Recommended Citation
Ybarra, Madeleine A., "The effects of native perennial cover on physiological indicators of habitat quality for sparrows in California coastal prairie rangelands" (2024). Cal Poly Humboldt theses and projects. 766.
https://digitalcommons.humboldt.edu/etd/766