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Publication Date

12-1-2011

Abstract

As White-winged Doves (Zenaida asiatica) and Great-tailed Grackles (Quiscalus mexicanus) expanded their range northward, these species have shown an increased affinity for urban areas, perhaps because of a constant supply of anthropogenic food sources. We compared use of bird feeders by both of these species to established avian species in urban central Texas. We used 15 feeding stations in San Marcos and 15 in San Antonio. We digitally recorded interaction events for half-hour intervals in summer 2009 and winter 2010. We used recordings to calculate total time spent by each species at each feeding station, count the number of aggressive interactions, and determine participants in each interaction. In summer, White-winged Doves and Great-tailed Grackles used feeding stations more than other avian species. In winter, there was little difference between feeding station use by White-winged Doves and Great-tailed Grackles; however, House Sparrows used feeding stations significantly more than both species. Whitewinged Doves were displaced by other species during summer but became more aggressive in winter, perhaps because food resources may have been limited more so in winter than summer. The results of our study are consistent with the possibility that maintenance of range expansion populations of White-winged Doves and Great-tailed Grackles has been facilitated by the ability of each species to use anthropogenic food sources.

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