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Bird Conservation

Examining the relationship between anthropogenic noise and nesting raptors during the COVID-19 pandemic


Karen Gallardo Cruz, Wildlife Biologist, Center for Environmental Management of Military Lands, Travis Air Forces Base:

Christopher Reddin, Natural Resources Support Coordinator, Center for Environmental Management of Military Lands:


In 2020, the COVID-19 pandemic led to a global shift in human behavior. Human activity decreased worldwide as people practiced social distancing and shifted from working in person to working from home. As restrictions lifted and vaccines became widely available in 2021, people returned to their offices and human activity returned to near pre-pandemic levels. These patterns provided a unique opportunity to study how noise from human activity affects wildlife. At Travis Air Force Base (TAFB), we were specifically interested in the effects of noise on nesting raptors, where TAFB currently requires a large buffer between the nest and construction projects to prevent impacts on nesting success due to anthropogenic noise. We placed automated acoustic recorders (SM4, Wildlife Acoustics) at four sites on Travis Air Force Base and recorded for a minimum of 39 days during 2020 and 2021. After each recording period, we surveyed the site for nesting and non-nesting raptors. We analyzed recordings with Kaleidoscope Pro and obtained Mean, Maximum, and Minimum Sound Pressure Levels (SPL) for recordings at each site, then compared these measurements between years using a paired t-test. For all sites, Mean and Min SPL levels were higher in 2021 than 2020, indicating an overall higher level of human activity and noise following the return of in-person office work. Nesting raptors and fledglings were found in three sites in 2020, but only found in one site in 2021, suggesting that the quieter ambient noise levels in 2020 resulting from the COVID-19 pandemic may have created more favorable nesting conditions for raptors. This study adds to our understanding of the ecological impacts of COVID-19, showing that decreases in human activity and noise can have positive impacts on nesting bird success.

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