Comparative physiological ecology of eastern and western hognose snakes (Heterodon platyrhinos and H. nasicus)

The physiological ecology of eastern and western hognose snakes are compared from an interspecific competition basis. Study methods included radiotelemetry, mark-recaptures, histological, anatomical and behavioral techniques. Eastern hognose snakes emerge from hibernacula in March, and enter hibernacula in November. Maximum activity of this species occurred in spring and again in fall, with little activity in summer. Optimum environmental temperatures ranged 31-34°C (x[bar]= 27.32). Western hognose snakes, on the other hand, emerged in May and apparently entered hibernacula in October. Maximum activity occurred from late spring to fall, optimum environmental temperatures also ranged 31-34°C (x[bar]= 31.8). Eastern hognose snakes are diurnal and crepuscular and exhibit triphasic activity patterns during part of the year. Western hognose snakes are diurnal only and exhibit diphasic activity patterns. Home ranges of eastern and western hognose snakes expanded from spring through summer, then decreased to hibernation. Eastern hognose snakes occupied the motte, while H. nasicus occur primarily in the grassland. Estimates of home range areas determined by telemetry were always larger than those obtained by mark-recaptures; hence, telemetry probably gives a more accurate figure. Movements of eastern hognose snakes decreased during summer, at which time, western hognose snakes invaded the woodland. Heterodon platyrhinos were again active in the woodland in fall, and H. nasicus moved back into the grassland at this time. ..