Inter-Research > ESR > v53 > p467-480  
Endangered Species Research

via Mailchimp

ESR 53:467-480 (2024)  -  DOI:

Distribution and drivers of critical hibernacula for the timber rattlesnake Crotalus horridus in Illinois, USA

Andrew C. Jesper1,*, Scott A. Eckert2, Scott R. Ballard3, John A. Crawford4, Michael J. Dreslik1

1Illinois Natural History Survey, Prairie Research Institute, Champaign, Illinois 61820, USA
2Department of Biology and Natural Resources, Principia College, Elsah, Illinois 62028, USA
3Illinois Department of Natural Resources, Carterville, Illinois 62918, USA
4National Great Rivers Research and Education Center, East Alton, Illinois 62024, USA
*Corresponding author:

ABSTRACT: The dependency on hibernacula for extended periods presents terrestrial reptiles with the challenge of locating thermally adequate hibernacula each winter. Defining the habitat characteristics of hibernacula is crucial for understanding the overwintering requirements and distributions of hibernacula-dependent reptiles, alongside identifying habitats which warrant special conservation concern. Our objectives were to identify the overwintering habitat characteristics of the imperiled timber rattlesnake Crotalus horridus in Illinois, USA, and to determine the distribution of likely hibernacula habitats throughout the state. Due to the initial sparsity of hibernacula records in Illinois, we adopted an iterative habitat suitability modeling process consisting of 3 distinct rounds of Maxent construction and revision. Each round was informed with updated information from model-guided surveys or by building rapport with in-state naturalists and researchers who knew of additional hibernacula locations. We created our final model using 36 hibernacula and identified slope angle (indicative of rock outcrops and shallow soils), topographical position index, forest patch area, and aspect (decomposed into 2 linearized variables: southness and eastness) as important drivers of C. horridus hibernacula habitat in Illinois. Together, the 5 variables and site surveys suggest the suitable overwintering habitat for C. horridus in Illinois is located on south- to southwest-facing outcrops on upper slopes and ridges of larger forest patches. Such habitat is distributed primarily in southern Illinois and throughout the Mississippi River and Illinois River border counties. Our study adds to the current understanding of the species’ overwintering requirements and provides a foundation for future ecological studies, management, and survey efforts throughout Illinois.

KEY WORDS: Habitat suitability model · Crotalus horridus · Hibernacula · Pitviper · Species niche model · Brumation

Full text in pdf format
Supplementary material
Cite this article as: Jesper AC, Eckert SA, Ballard SR, Crawford JA, Dreslik MJ (2024) Distribution and drivers of critical hibernacula for the timber rattlesnake Crotalus horridus in Illinois, USA. Endang Species Res 53:467-480.

Export citation
Share:    Facebook - - linkedIn

 Previous article Next article