Community structure of snakes in a human-dominated landscape Original Research Article

We studied occupancy, species richness, abundance, and size distributions of snakes on habitat patches that ranged from 0.2 to 120 ha within a landscape undergoing substantial land-use changes. Additionally, we examined the role of intraguild predation in structuring snake communities by equipping five racers (Coluber constrictor, the largest snake in our study area) with transmitters, and then compared the abundance of smaller snakes within areas of intensive (75% isopleth home range) and limited activity (outside of 75% isopleth) by racers. As expected, small patches (<1.5 ha) often were vacant or occupied by only one species (garter snakes, Thamnophis sirtalis). Species richness was greatest on large patches, and snakes also tended to be more abundant on large patches. Counter to our expectations, the proportion of large-bodied individuals on small patches was greater. The distribution of small-bodied snakes on one large patch may have been affected by racers because the proportion of small snakes was less in areas intensively used by racers. Additionally, the abundance of the most generalist species in our study (garter snakes) was less in areas of intensive use by racers. In the northeastern United States, populations from a variety of taxonomic groups (including insects, migratory songbirds, mammals, and snakes) are rapidly declining in response to the loss of early-successional habitats. Our study lends support to current initiatives that recommend restoration and maintenance of parcels of early-successional habitats to sustain regional biological diversity.