Habitat Use and Behavior of Great-tailed Grackles (Quiscalus Mexicanus) in Urban and Peri-Urban Habitats of San Marcos, Hays County, Texas

Abstract

Great-tailed grackles (Quiscalus mexicanus) are habitat generalists occupying a wide variety of environments, except dense forests and prairies lacking nearby water sources. Suitable habitat, such as golf courses, campuses, lawns, parks, and streets are also inhabited in urban and suburban areas. There are seasonal differences in habitat use by great-tailed grackles; however, habitat use and behavior have not been examined in urban environments. The goal of this study was to document seasonal use by great-tailed grackles of urban and peri-urban habitats in San Marcos, Hays County, Texas. I also documented behaviors observed in the different habitat types. I compared habitat use by season and behavior by season and habitat. I used program Presence to apply the best fit model explaining occupancy within habitats. Chi-square goodness of fit tests indicated no differences in behavior between seasons and habitat types. Principal components analysis suggested differences in woody vegetation among study sites. The best fit model incorporated occupancy, colonization and detection with habitat type and time of day as covariates. I found great-tailed grackles selected developed areas (85%) over open (60%) and wooded (27%) habitats based on occupancy modeling. Great-tailed grackle behavior changed by season and by habitat type.