Spatial Ecology and Habitat Selection of the Northern Cottonmouth, Agkistrodon Piscivorus, Within Constructed Wetland Complexes

Document Type


Degree Name

Master of Science (MS)


Biological Sciences

Date of Award

Summer 2018


Agkistrodon piscivorus (Northern Cottonmouth) is an abundant semi-aquatic pit viper. However, in comparison to many other pit viper species, there are few telemetric spatial ecology or site selection studies on A. piscivorus. I radio tracked 44 adult A. piscivorus throughout the active season, and 12 neonate A. piscivorus from parturition to hibernation. Adult male’s 95% kernel density estimate (KDE) home ranges were significantly larger (X̅ = 41.3 ha) than adult female’s (X̅ = 7.04 ha; P = 0.0006). Male’s weekly distances travelled (X̅ = 110.07 m) were significantly longer than female’s (X̅ = 45.04 m; P = <0.001). Both sexes made fall migrations to hibernacula, and return migrations to the wetland in the spring. These migrations are most likely made for food, mating, hibernacula, and thermoregulatory resources. At the second-order scale, male home ranges were based around wetland (Manly Selection Ratio [MSR] = 1.53, 95% CI = 1.23 to 1.83), and female home ranges showed no preferences. At the third-order scale, only summer male cover preferences were significant (compositional analysis, P = 0.002), as they preferred edge and wetland cover. At the fourth-order scale, both sexes selected microsites with greater vegetative concealment in the spring and summer due to predator avoidance and thermoregulation. In the fall, microsite selection was influenced by mating and parturition. Neonates home ranges were minute (95% KDE = 1.15 ha), as they did not disperse far from parturition sites (X̅ = 159.7 m). At the second-order scale, neonate home ranges contained significantly more edge cover (MSR = 1.717; 95% CI = 1.2556 to 2.1792). At the fourth-order scale, neonates selected microsites with thick ground cover and canopy cover. I believe neonate selection, lack of dispersal, and small home ranges are because of gravid female parturition migrations. All of my findings stress the importance of ecotones, as dominant species such as A. piscivorus depend on them for parturition, upbringing, and hibernation.


Johanna Delgado-Acevedo

Subject Categories

Biology | Ecology and Evolutionary Biology | Life Sciences