Occupancy models disentangle the drivers of avian urban avoidance in North America?s largest urban forest

Urbanization dramatically modifies natural landscapes, fragments previously intact habitats, and is spreading rapidly, making it one of the leading causes of worldwide biodiversity decline. We studied the impact of urbanization on the occupancy of breeding birds in the Great Trinity Forest in Dallas, TX, the largest urban forest in the United States. The matrix of habitat surrounding the Great Trinity Forest varies from highly urbanized industrial landscapes to more rural areas. Between May 15th and July 15th of 2018, 2019, and 2020 we surveyed 404 5-ha plots for forest birds, recording 4274 observations representing 49 species. We used time-to-detection to model avian occupancy in 17 species while accounting for false absences. We found that the avian community responded to anthropogenic impacts of urbanization in the matrix in diverse ways. Urbanization intensity had the largest negative impact on avian occupancy and best explained observed patterns of urban avoidance from previous studies. Occupancy of species with low vocal frequency was negatively impacted by continuous anthropogenic noise from automobile traffic, while a broader group of species was negatively impacted by intermittent noise from airplane traffic. Occupancy exhibited both positive and negative responses to increased feral hog activity. To maintain diverse bird communities in forest fragments with a heavily urbanized matrix, it may be necessary to maintain large habitat tracts and mitigate for the indirect effects of the matrix like noise and invasive species.