Triggers and Timings of Spring Emergence for the Timber Rattlesnake (Crotalus horridus) in Illinois

Jesper, Andrew C.B.

Dreslik, Michael J.

Illinois Natural History Survey

Prairie Research Institute

Champaign, Illinois, USA

Colder periods in temperate regions force many reptiles to retreat into insulated hibernacula to survive. Reduced activity and metabolic rates during this period, paired with low internal hibernacula temperatures, results in extreme lethargy, limiting a reptile’s capacity to avoid potential threats including predation, fire mortality, and human persecution. Spring emergence amplifies such threats when reptiles leave the relative safety of hibernacula and become exposed on the surface. Communally hibernating reptiles, such as the threatened Timber Rattlesnake (Crotalus horridus), which emerge and congregate in the immediate denning area are at greater risk due to artificially high densities. Information regarding the timing and triggers of spring emergence for the Timber Rattlesnake is required to inform conservation and land management. Here, we report our findings on the phenology and temperature triggers of spring egress for the Timber Rattlesnake at 9 hibernacula across the latitudinal gradient of Illinois during 2018 and 2019.

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