Graduation Year

2026

Date of Submission

4-2026

Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts

Department

Biology

Reader 1

Elise Ferree

Reader 2

Robert Brodman

Abstract

The Southern California chaparral ecosystem is adapted to infrequent, high-intensity fire, but increasing fire frequency due to climate change is creating new ecological conditions that challenge the resilience of native wildlife. Despite this growing threat, little is known about how nocturnal bird communities respond to post-fire habitat changes. This study investigates the importance of unburned patches within a burn scar on the activity and abundance of nocturnal bird species. Using passive acoustic monitoring, I deployed 12 recorders across burned and unburned sites along an elevational gradient on Sunset Peak, one year after the 2024 Bridge Fire. Recorders sampled continuously overnight for 11 nights per month across six months (October through March), and calls were identified using BirdNET. I detected five nocturnal bird species (Great Horned Owl, Western Screech-Owl, American Barn Owl, Common Poorwill, and Lesser Nighthawk) and compared call rates and proportion of nights present between burned and unburned areas. Burn status, month, and their interaction were significant predictors for several species, but effects were species-specific and seasonally variable rather than uniformly negative for burned areas. Great Horned Owls showed the strongest preference for unburned habitat across both metrics, consistent with their dependence on mature vegetation for nesting, perching, and hunting. January was a low point in activity for all species, while March was a high point, likely due to breeding. These results show that fire restructures nocturnal avian communities in ways that are invisible to traditional diurnal survey methods. They also demonstrate the value of passive acoustic monitoring for detecting small-scale temporal and spatial variation in post-fire bird communities.

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This thesis is restricted to the Claremont Colleges current faculty, students, and staff.

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