Can simulated rainfall vibration release rain-harvesting behavior in Prairie Rattlesnakes (Crotalus viridis)?

Merkel, Bridget K.

bobacks@dickinson.edu

Caton, Josephine M.L

Department of Biology

Dickinson College

Carlisle, Pennsylvania USA

Goetz, Scott M.

United States Department of Agriculture

APHIS-WS National Wildlife Research Center

Fort Collins, Colorado USA

Rockwell, Parker, M.

Department of Biology

James Madison University

Harrisonburg, Virginia USA

Boback, Scott M.

Department of Biology

Dickinson College

Carlisle, Pennsylvania USA

Many desert-dwelling ectotherms exhibit overt responses to rainfall, but the physical stimuli involved in activating such behaviors are typically presumed or unexplored. Some pitvipers show stereotyped behaviors that enhance rainwater collection on their skin, such as coiling and flattening their bodies, referred to as rain-harvesting behavior. Pitvipers are slow-moving, secretive animals that limit their exposure for safety and thermoregulation by spending large amounts of time underground or under natural cover (e.g., rodent burrows, rock ledges). However, to effectively capture rain, snakes must be at the surface with their bodies exposed to the sky or at least located where precipitation will accumulate. This presents a dilemma: how might snakes hiding underground detect surface rainfall to capitalize on sporadic, short-duration rain events? In this project, we aimed to test one of the potential cues used by snakes to detect rainfall, namely ground-borne vibrations. Previous work in other ectotherms (desert toads) found that vibrations alone can elicit emergence behavior typical of the monsoon season. In a pilot study at our study site with Prairie Rattlesnakes (Crotalus viridis), we recorded ground-borne vibrations during natural and fabricated rainfall using an accelerometer placed just below the soil surface to generate an artificial playback file. We then designed a field apparatus to transmit the vibrations into multiple natural substrates while we observed the responses of individual rattlesnakes to these playbacks. Our results could reveal the role of vibrational signals in the sensory ecology of pitvipers and broaden our appreciation for their complex sensory modalities.