Urbanization is a growing threat to avian species. As forest habitats succumb to man-made structures, the loss of tree cavities results in a lack of nesting areas. The addition of nest boxes, however, can greatly benefit secondary cavity nesters that are breeding in such environments. Although many native species use these boxes, invasive species also take advantage of them. We investigated how urbanization affects nest box occupancy on the suburban SUNY New Paltz campus in New Paltz, NY. We installed 9 nest box pairs across our campus evenly divided into forest edge, residential, and central (the most urbanized) urbanization categories, and monitored them every 3-4 days from March to August of 2016. We then used aerial photographs and GPS units to create land cover maps of 10 and 50-meter radius circles around each nest box pair using ArcGIS software. We measured the following land cover types; impervious surface, water, plantings, and natural forest. We used the land cover areas to identify which factors predicted nest box occupancy. We expected to see a greater variety of native species in the forest edge boxes with more forest cover, and more invasive species in the central nest boxes with more impervious surface cover.
A variety of birds used the nest boxes; house sparrows, tree swallows, Eastern bluebirds, house wrens, tufted titmice, and black-capped chickadees. Overall, five different species occupied the forest edge nest boxes, three occupied the residential nest boxes, and two occupied the central nest boxes. The mean percentage of invasive house sparrow nests at the central locations was about 89%, much higher than residential and forest edge boxes. Although the percentage of house sparrows occupying nest boxes was significantly higher in the central urbanization category, it was not correlated with any specific GIS land cover. House sparrow occupation is, however, correlated with the distance of each nest box to the center of campus (most pedestrian traffic and impervious surface). Although diversity was greatest in our forest edge category of nest boxes, Eastern bluebirds had 100% success in fledging 3 broods of young in two of our residential boxes. Our results suggest that it is indeed worthwhile to provide nest boxes in suburban areas. The trends we observed may provide insight into the optimum placement of nest boxes in order to encourage a greater variety of native bird species.