Graduation Year

2025

Document Type

Open Access Senior Thesis

Degree Name

Bachelor of Arts

Department

Biology

Reader 1

Elise Ferree

Reader 2

Wallace M. Meyer

Abstract

The increasing frequency and intensity of wildfires pose growing threats to wildlife, yet the indirect effects of wildfire smoke on avian populations remain largely unstudied. This exploratory study provides an initial assessment of how particulate matter 2.5 (PM2.5) associated with smoke pollution from the 2017 California wildfire season, in conjunction with precipitation and habitat type, influences the body condition of four resident bird species during the 2018 breeding season. Using bird banding data from 29 Monitoring Avian Productivity and Survivorship (MAPS) stations, I assessed the potential interactions between PM2.5 concentrations, precipitation, and habitat type with body condition for Song Sparrows (Melospiza melodia), Orange-crowned Warblers (Vermivora celata), Bewick's Wrens (Thryomanes bewickii), and Wrentits (Chamaea fasciata). Linear mixed-effects models revealed varying significance of interaction effects with both habitat and precipitation, with some species-specific responses, highlighting the need for expanded, multi-year investigations. Contrary to initial predictions, some species like Orange-crowned Warblers and Wrentits exhibited improved body condition with decreased precipitation level and increased PM2.5 exposure, potentially due to altered foraging dynamics or insect behavior. This may suggest that birds are more resilient to environmental change than previously expected. These findings reinforce the complexity of wildfire smoke impacts on avian health, highlighting the importance of considering species-specific and environmental contextual factors. Recommended future directions include expanding the study to include additional years for wildfires and breeding season morphometric data, incorporating more balanced sampling across species and habitats, and extending research beyond California to other regions experiencing increased wildfire activity. This foundational research represents an initial step in understanding the nuanced ways wildfire smoke may impact avian populations, setting the stage for more comprehensive monitoring and research on wildlife responses to smoke pollution.

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