Graduation Date
Fall 2025
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
Cal Poly Humboldt Faculty or Staff
Second Committee Member Name
Frank Fogarty III
Second Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Third Committee Member Name
Daniel Barton
Third Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Keywords
Community ecology, Napa Valley, Ecosystem services, Biocontrol, Nest boxes, Habitat, Vineyards
Subject Categories
Wildlife
Abstract
Agricultural expansion threatens biodiversity, but integrating insectivorous birds into vineyard ecosystems may support both conservation and ecosystem services. We tested how nest boxes and habitat composition influence avian and arthropod communities in Napa Valley vineyards using a before-after, control-impact experiment across 20 sites. During the 2023-2024 breeding seasons we conducted avian point counts, sampled key pest and beneficial arthropods, and collected fecal samples from adult and nestling tree swallows (Tachycineta bicolor) and western bluebirds (Sialia mexicana) to detect vineyard pest DNA. Nest boxes significantly increased swallow and bluebird abundance within one year; swallow responses were strongest near installed boxes, whereas bluebirds increased across vineyards. Pest counts declined farther from riparian habitat after boxes were added and we found no clear evidence that boxes altered beneficial arthropods. Pest DNA was detected in a subset of fecal samples, confirming consumption of target taxa by both swallows and bluebirds. Additionally, we examined how habitat effects insectivorous bird abundance and their arthropod prey. Foliage-bark gleaners were more abundant with greater local habitat heterogeneity and proximity to forest and riparian edges. Local habitat heterogeneity also increased arthropod abundance and order level diversity, boosting prey availability at structurally complex sites. Together, these results indicate that nest boxes draw avian predators into vineyards where they may reduce pests away from riparian edges, and that fine scale heterogeneity and adjacent forest and riparian habitats sustain gleaners and arthropod prey, aligning biodiversity and pest control goals in vineyards.
Citation Style
APA
Recommended Citation
MacDonald, Eleanor, "Examining the effects of songbird nest boxes and habitat on avian and arthropod communities in a vineyard ecosystem" (2025). Cal Poly Humboldt theses and projects. 2511.
https://digitalcommons.humboldt.edu/etd/2511
Collaboration
1
Included in
Biodiversity Commons, Entomology Commons, Ornithology Commons, Other Ecology and Evolutionary Biology Commons