Three of the 10 presentations by the INHS PaCE Lab were part of the Snakes in Winter Symposium organized by Bruce Kingsbury.
Dr. Dreslik presented “Fidelity to Over-wintering Refugia in the Eastern Massasauga (Sistrurus catenatus)” with co-authors Emily L. Sunnucks and Zander E. Perelman.
Colder seasons associated with latitude or elevational changes often influence the behavior and physiology of ectotherms. For temperate-zone snakes, suitable overwintering sites tend to be limited, forcing high rates of fidelity and even vernal and autumnal migratory events. The Eastern Massasauga (Sistrurus catenatus), a federally threatened rattlesnake, relies on specific refugia such as crayfish burrows at their southern range limit. Our study explores the spatial and temporal fidelity to overwintering sites using mark-recapture data (1999 – 2025) and radio-telemetry data (2000 – 2003) collected near Carlyle Lake, Illinois. The research quantifies whether snakes show fidelity to specific overwintering sites and if variation in fidelity is explained by sex and size. We also examine if active season movements centered on previously used refugia. With long-term data, we aim to improve the understanding of overwintering behavior and its conservation implications in fragmented landscapes.
ARC lead Ethan Kessler presented “Drivers of Autumnal Retreat and Vernal Emergence from Overwintering Refugia in the Eastern Massasauga (Sistrurus catenatus)” co-authored with MJ.Dreslik.
Annual survival in temperate snake species is dependent upon brumation in overwintering refugia, which protect individuals from harsh winter conditions. The timing of refugia use has novel implications in the face of anthropogenic threats, including the timing of prescribed burns and other intensive habitat management techniques. Understanding triggers of autumnal retreat and vernal emergence is crucial for scheduling habitat management activities, which improve habitat quality but can cause incidental mortality. We used a radiotelemetry dataset of the federally threatened Eastern Massasauga (Sistrurus catenatus) in Illinois, consisting of 4,822 locations (2000-2003 and 2008-2009), to determine the drivers of hibernacula use. We found the interaction of day of the year and soil temperature best predicted burrow use in the fall and spring. Lower soil temperature prompted burrow use in early fall and delayed emergence in late spring, but was less predictive in winter months as burrow use became nearly universal. Our study offers insight into the overwintering ecology of S. catenatus, while also providing a predictive model of burrow use based on easily measured variables, creating a practical tool for land managers to schedule activities and minimize mortality.
PhD candidate Zander Perelman presented “Overwinter Burrow Sharing by Eastern Massasaugas (Sistrurus catenatus) in South-Central Illinois” co-authored with Donald Shepard, Benjamin Jellen, and M.J. Dreslik.
Surviving winter is challenging for temperate-zone ectotherms and suitable refugia can be limited, especially at northern latitudes. Such harsh environmental pressures have driven the evolution of physiological and behavioral adaptations that increase overwinter survival. One such behavioral adaptation is communal denning, where natural features provide refuge for multiple individuals or species to overwinter together, sometimes at the scale of hundreds (e.g., Timber Rattlesnakes; Crotalus horridus) or even thousands (e.g., Red-Sided Gartersnakes; Thamnophis sirtalis parietalis) of individuals. Although Eastern Massasaugas (Sistrurus catenatus) occur near the northern range limit of temperate-zone pitvipers, they typically overwinter solitarily using refugia such as crayfish or mammal burrows, tree root systems, bedrock cracks and fissures, wetland hummocks, and spring seeps. No studies have explicitly examined Eastern Massasauga communal use of overwintering sites. Here, we used observations made during radiotelemetry study to characterize the frequency, demographics, and species diversity of overwinter site sharing in a population of Eastern Massasaugas in south-central Illinois. We found Eastern Massasaugas occasionally shared crayfish burrows (~7% of the time; 134/1970 total observations of Eastern Massasaugas in crayfish burrows) with both conspecifics and heterospecifics, and we examined how sex and life stage possibly influence burrow sharing. We discuss potential future research directions and the conservation implications of overwinter site-sharing behavior in Eastern Massasaugas and other imperiled temperate-zone snake species.
