SPATIAL ECOLOGY AND MICROHABITAT SELECTION OF THE PYGMY RATTLESNAKE (SISTRURUS MILIARIUS) IN SOUTHWESTERN MISSOURI, USA

Understanding use of space and habitat are central to animal ecology and provide insight into resource selection patterns. Despite a wide distribution throughout the southeastern U.S., research on Pygmy Rattlesnakes (Sistrurus miliarius) has been largely restricted to Florida populations. We studied S. miliarius in a managed forest landscape on a state conservation area in the Ozarks of southwestern Missouri, near their northern range limit, during 2016 and 2017. We captured 54 S. miliarius, primarily during evening road driving surveys, and used 19 (six males and 13 females: nine gravid, four nongravid) for a radiotelemetry study. Telemetered snakes were relatively sedentary, making short, infrequent movements that resulted in small home range estimates (range, < 0.001-2.6 ha). Reproductive status of females strongly affected activity with mean movement distances and home range sizes of gravid females increasing live-fold following parturition. We encountered S. miliarius in all available habitat types, suggesting that habitat selection was mainly occurring at the microhabitat scale. Snakes were very secretive but typically concealed themselves within vegetation (89% of observations) or beneath surface cover (8.5% observations) rather than underground. Snakes selected microhabitats with more vegetative cover and woody debris, and less leaf litter, than random sites. The ability of S. miliarius to use a variety of habitat types suggests that it is well adapted to the Ozarks landscape. Our study presents novel information to a growing body of knowledge on S. miliarius ecology that should lead to comparative studies in different geographic regions.

Automated summary

Understanding the microhabitat selection and movement patterns of Pygmy Rattlesnakes in the Ozarks region of Missouri, this study found that these snakes are well adapted to a variety of habitat types and predominantly select microhabitats with more vegetative cover and woody debris. The reproductive status of females significantly affects their activity levels.