Interior forests provide refugia for breeding birds from anthropogenic heat and sound pressure
Date
2025
Authors
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Publisher
University of Delaware
Abstract
Urbanization and the associated increase in human activities is a major driver of global change. Among many other threats, urbanization affects climate regimes and human development alters which sounds are prevalent in the environment. The national parks in the National Capital Region Inventory & Monitoring Network (NCRN) are uniquely situated within the highly urbanized Washington D.C. metro region, protecting natural areas along an urban-rural gradient and offering a unique opportunity to study the effects of anthropogenic pressures on biodiversity in small urban parks. I utilized long-term monitoring of the breeding bird community in NCRN parks to study the effects of two uncommonly studied anthropogenic stressors: heat and noise pollution. Using multivariate generalized linear models, I tested the effects of local land surface temperatures (LST) on the bird community and how those relationships may be affected by surrounding land use: either forested, urban, or agricultural dominated landscapes. I found that the abundance of the bird community responded negatively to increased LST, especially for species with specialist traits. Areas with greater forest cover within the surrounding landscape help to mediated the negative effects of LST on abundance by providing habitat that was on average > 2°C cooler than urban or agricultural dominated landscapes. Sound pollution is another important threat from urbanization surrounding national parks, and I tested the efficacy of acoustic indices to predict bird diversity. Acoustic indices are methods to quantify and assess sound in the habitat. The strongest relationships occurred between the acoustic index which measures anthropogenic noise pollution (Normalized Difference Sound Index, NDSI) with bird community integrity, and both NDSI values and bird community integrity were strongly related to distance to major roads. These relationships jointly indicated that acoustic indices are quantifying the level of noise pollution from vehicle traffic, and that higher quality bird habitat occurs further away from roads. My thesis highlights the importance of intact forest habitat to help forest birds contend with the anthropogenic pressures of excess heat and noise pollution. Interior forest habitat buffers the negative effects of these pressures and provide higher quality breeding bird habitat. By examining how external pressures affect protected lands, my findings add to the current understanding of habitat quality and will help guide local- and regional-scale land management decisions.
Description
Keywords
Anthropogenic threats, Bird community, Forest birds, Noise pollution, Specialist guilds