Bats in New York City: An Acoustic Survey and the Role of Green Roofs

Understanding bat use of human-altered habitat is critical for developing effective conservation plans for this ecologically important taxon, and gathering baseline data is important for tracking the regional status of bat species. I monitored bat activity at four sites in the Bronx, NY using passive and active acoustic recording methods from May 2012 – Feb 2013. I then identified bat vocalizations on these recordings to the species level. I documented the presence of five of the nine possible bat species that are present in New York State; the majority of bat calls that could be identified to the species level were from Eastern Red Bats (Lasiurus borealis). Migratory bat activity peaked in August and October, and three species were recorded during the winter months. I also investigated the extent to which bats utilize green roofs in New York City (NYC). Green roofs, building rooftops covered in growing medium and vegetation, are increasingly important conservation tools that make use of underutilized space to provide breeding and foraging grounds for urban wildlife. Green roofs are especially important in highly urbanized areas such as NYC, which has more rooftops (34%) than green space (13%). I monitored bat activity using recorders on four green and four conventional roofs located in highly developed areas of NYC, which were paired to control for location, height, and local variability in surrounding habitat and species diversity. I documented the presence of five bat species over both roof types; the majority of bat calls that could be identified to the species level were from Eastern Red Bats (Lasiurus borealis). Bat activity peaked in August. Overall levels of bat activity were higher over green roofs than over conventional roofs. This study provides evidence that, in addition to well documented ecosystem benefits, urban green roofs contribute to urban habitat availability for several North American bat species