Avian metapopulation dynamics in a fragmented urbanizing landscape

Abstract

As urbanization transforms landscapes around the globe, we are challenged to find ways for urban habitats to contribute to ongoing wildlife conservation efforts. Yet aside from basic distributions and relative abundance, we know little about the population dynamics of most species occupying urban habitats and almost nothing about the extent to which local populations serve as source or sink habitats. We analyzed the spatial synchrony and persistence of local populations of 16 avian species breeding in 14 mature riparian forests in central Ohio, USA during 2005–2011. In addition, we examined demographic growth rates (λ) for 2 focal species (northern cardinal, Cardinalis cardinalis, and Acadian flycatcher, Empidonax virescens) to understand source-sink structure. Our results showed high rates of population turnover for the majority of species and negative growth rates for both focal species, indicating that most populations functioned as sinks. Local populations showed little evidence of population synchrony, as we found consistently low or negative spatial autocorrelation and relatively high rates of population turnover for both migratory and resident species. Collectively our results suggest that long-term persistence of regional populations of birds breeding in Midwestern riparian forest fragments may be facilitated by metapopulation dynamics.