Effects of forest structure on the distribution of southern flying squirrels (Glaucomys volans) in urban parks

Abstract

Although southern flying squirrels (Glaucomys volans) are present in many urban parks, squirrel-habitat relationships in such areas are poorly understood, limiting conservation efforts. Our objective was to quantify the effects of forest structure at multiple scales on flying squirrel distribution in New York City (NYC) parks. From 18 June–24 August 2001, we captured flying squirrels in 5 New York City parks and measured forest structure at the ground, shrub, understory, and overstory levels at trap sites. To examine the importance of forest structure to squirrels, we compared (1) habitat variables between trap stations where squirrels were captured and not captured and (2) habitat variables between parks with and without documented squirrel populations. Our data suggest that areas with forests containing smaller trees at higher densities, dense woody ground cover, and little herbaceous ground vegetation may not provide the food, cavities, ease of movement, or allow predator detection necessary to be used by or support flying squirrel populations. Other factors, such as the size and density of stumps and snags may be important to non-urban squirrel populations, but not populations in NYC parks. Because NYC parks contain almost all of the remaining woodlands within the City, forests within these areas should be a conservation priority.