Ecosphere (Jan 2019)
Site‐specific differences in the spatial ecology of northern cottonmouths
Abstract
Abstract We conducted a yearlong telemetric study on 44 northern cottonmouths (Agkistrodon piscivorus) and recorded their weekly spatial position and use at two different and unconnected wetlands: Cooper Wildlife Management Area (Cooper WMA) and Texas A&M Commerce Wetland Area (Commerce WA). These wetland sites differed in size, but were nearly identical in general locality, structure, hydrology, vegetative composition, available resources, and biodiversity. Home ranges for male cottonmouths at the larger Cooper WMA (n = 16; 95% kernel density estimate (KDE) X¯ = 54.69 ha ± 9.36; 100% minimum convex polygon (MCP) X¯ = 22.9 ha ± 4.19) were significantly larger than those at the smaller Commerce WA (n = 10; 95% KDE X¯ = 19.88 ha ± 4.71; 100% MCP X¯ = 8.98 ha ± 2.27). The home ranges of males (n = 26; 95% KDE X¯ = 41.3 ha ± 6.84; 100% MCP X¯ = 17.55 ha ± 3.00) were also significantly larger than those of females (n = 7; 95% KDE X¯ = 7.04 ha ± 1.81; 100% MCP X¯ = 3.08 ha ± 0.82) at both sites. We found no relationship between body size and home range size at either study site. Average weekly distance traveled by males (X¯ = 110.07 m ± 10.80) was significantly greater than that of females (X¯ = 45.04 m ± 4.34), and male movement rates were bimodal in distribution with peaks of movement in the spring and fall. These peaks in movement rates coincided with the spring and fall migrations for mating, thermoregulation, parturition, and access to hibernacula and food resources. We found home ranges within these two‐dimensional wetlands to be larger than those reported for linear or one‐dimensional riparian sites. We discuss how wetland size and the size‐dependent dispersion of potential resources within similar wetlands may influence movement patterns and home range sizes. Such information may serve to evaluate effective wetland size for the conservation and management of wetland species.
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