Urban Wild Bird Feeding: Impacts on Avian Abundance and Diversity in Texas




Lamberson, Amanda Michelle

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The provision of supplementary food to wild birds is widespread in developed nations. Previous studies of effects on birds have mainly occurred in temperate, non-urban settings, and during the breeding season. In this study, effects of supplementary food on the abundance and diversity of birds were evaluated during the winter in San Antonio, Texas, an urban, subtropical city. Specifically, 1) sales data were used to investigate wild bird food bought by residents, 2) surveys of residents were used to assess bird feeding practices, including what food types they provide, when, and how often, and 3) I used data from Objective 1 to assess the effects of commonly provided food on the abundance and diversity of birds in a field-based study. Results suggest mixed and Nyjer seed were among the most purchased foods. Thus, to address Objective 3, in the winter of 2019-2020, 36 sites were randomly allocated either mixed seed, Nyjer seed, or no food (control); and counts were conducted to assess the bird diversity and abundance. Counts were repeated the following winter with no food at sites as part of a reversed Before-After-Control-Impact experimental design. The abundance and diversity of birds were greater at fed sites than non-fed sites in Year 1. In Year 2, both abundance and diversity decreased at mixed seed sites. However, Nyjer sites had similar abundance and diversity in Year 2 compared to Year 1. This study demonstrates that supplementary food has a significant effect on bird abundance and diversity, but effects are context specific.


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abundance, bird, diversity, food, supplementary, urban



Integrative Biology