GIS impervious land cover metrics predict fitness variation in a neotropical migrant, the house wren (Troglodytes aedon)

Urbanization can fundamentally change the ecology of an area and impact breeding bird populations. Therefore, predicting how urbanization alters anthropogenic disturbance regimes and the fitness of breeding birds are important components of understanding how human-altered environments impact natural bird populations. We investigated whether impervious land cover predicts patterns of anthropogenic disturbance and variation in house wren (Troglodytes aedon) fitness at sites around Williamsburg, VA. We collected temporal and spatial disturbance data at 57 bird nest boxes and generated multivariate measures of disturbance regimes using PCA. With GIS, we digitized impervious land cover within 100 meters (i.e. the breeding territory) of each box. Impervious surface area and perimeter strongly predicted overall temporal disturbance. Increased anthropogenic disturbance of the nest occurred when buildings were closer to the nest and there were more roads and paths in the breeding territory (r² = 0.603). Importantly, we also found that GIS parameters predicted fitness variation among breeding pairs of house wrens. Pairs fledged more offspring from the nest in areas with relatively more roads and paths in their breeding territory (r² = 0.443). These results indicate that GIS land cover data can predict fitness variation, although the nature of this relationship is likely to vary among birds with different life histories. Therefore, by expanding this study to other species, we can form predictive models of how urbanization will alter the fitness of local populations and alter avian community structure.