Den-Tending: Documentation of a Novel Reproductive Behavior of the Western Diamond-backed Rattlesnake (Crotalus atrox) at a Den in Northwest Arkansas

Beaupre, Steven J.

sbeaupre@astate.edu

Department of Biological Sciences

University of Arkansas

Fayetteville, AR

Dean of the Graduate School

Arkansas State University

Jonesboro, AR

Isaac Lord

Department of Biological Sciences

University of Arkansas

Fayetteville, AR

Brad Birchfield

Para-Herpetologist

Mountainburg, AR

Jeremy Sloan

Para-Herpetologist

Greenwood, AR

J.D. Willson

Department of Biological Sciences

University of Arkansas

Fayetteville, AR

Max Carnes-Mason

Department of Fisheries, Wildlife, and Conservation Sciences

Oregon State University

Corvallis, OR

Reproductive behaviors of rattlesnakes, especially the Western Diamond-backed Rattlesnake (Crotalus atrox), have been extensively described. Schuett et al. identified “sentinel” males that monitor or guard multiple females at dens during egress. We suggest the term “Den-Tending” to describe additional behaviors of these “sentinel males. We observed extensive den-tending at a den site in the Boston Mountains of Arkansas during spring egress (2023, 2024) using Motion-activated cell (Tactacam Reveal 2.0™, Decorah, IA) and timelapse cameras (Reconyx Hyperfire 2, Holmen, WI). Three cameras were positioned to monitor the den entrance and immediately adjacent ground. Once triggered, the cameras recorded a still and ten seconds of continuous video, resulting in a large collection of stills and short videos. Visual records were reviewed and assembled into video sequences using Davinci Resolve 19 (version 19.1.3, ©2024, Blackmagic Design PTY, LTD).  We gathered over 100 images and sequences of two sentinel males that exhibited den-tending. These two males engaged in repeated agonistic combats with each-other during the emergence/mating season. Den-tending behaviors were only observed when one of these two snakes was present at the den (never both). Den-tending consisted of three behaviors: (i) patrolling, (ii) chemosensory search of substrate at the entrance, and (iii) ambushing emerging conspecifics at the den entrance.  “Patrolling” consisted of co-dominant males pacing back and forth in front of the den.  Patrolling was interrupted by sessions of chemosensory searching of the rocks, ground, and crevices in front of the den.  When ambushing conspecifics both snakes exhibited an elongated body posture with the head roughly centered in a basking space directly in front of the den entrance. Snakes that emerged to ambushing males were greeted with immediate agonistic challenge, immediate courtship, or complete indifference. Den-tending is a distinct and identifiable reproductive behavior displayed by C. atrox sentinel males.