The Spatial Ecology of the Timber Rattlesnake (Crotalus horridus) in southeastern Louisiana

The Timber Rattlesnake (Crotalus horridus) has a large distribution spanning much of the eastern United States. Because temperature, habitat type, prey composition and abundance, and a variety of other factors may dictate reptile behavior, populations of conspecific species may exhibit behavioral differences across latitudinal and elevational gradients. Using radio telemetry, we tracked 10 adult Timber Rattlesnakes (7 males, 3 females) from May 2016 to June 2017 in southeastern Louisiana to examine the spatial ecology of male and non-gravid female snakes. Mean annual and seasonal home ranges of non-gravid female Timber Rattlesnakes were not statistically different from that of males. Mean seasonal home range sizes and average distances travelled of both sexes was smallest in winter, and had a general increasing trend beginning in spring with a peak in fall. These increases seemed to coincide with the breeding season, taking place from early July until the end of November. Comparison of this study with other studies throughout its distribution could have implications towards future management of conservation for other southern populations of Timber Rattlesnakes.

Variation in behavior drives multiscale responses to habitat conditions in timber rattlesnakes (Crotalus horridus)

Variations in both the behavior of wildlife and the scale at which the environment most influences the space use of wild animals (i.e., scale of effect) are critical, but often overlooked in habitat selection modeling. Ecologists have proposed that biological responses happening over longer time frames are influenced by environmental variables at larger spatial scales, but this has rarely been empirically tested. Here, we hypothesized that long-term patterns of behavior (i.e. lasting multiple weeks to months) would be associated with larger scales of effect than more sporadic behaviors. We predicted site use by 43 radio-telemetered timber rattlesnakes (Crotalus horridus) exhibiting four distinct, time-varying behaviors (foraging, digestion, ecdysis, and gestation) using remotely-sensed environmental variables related to forest structure and landscape topography. Among sites used by snakes, warmer temperatures and higher levels of forest disturbance were predictive of behaviors dependent on thermoregulation including gestation and ecdysis while more moderate temperatures and drier, more oak-dominated sites were predictive of foraging. Long-term behaviors were associated with larger spatial scales, supporting our hypothesis that the scale at which habitat selection occurs is linked to the temporal scale of relevant behaviors. Management recommendations based on single-scale models of habitat use that do not account for fine-scale variations in behavior may obscure the importance of potentially limiting habitat features needed for infrequent behaviors that are critically important for growth and reproduction of this and related species.