Field-Based Observations of Strike-Induced Chemosensory Searching (SICS) in Timber Rattlesnakes (Crotalus horridus) Reveal a Potential Role for Olfaction via Ventilation Patterns

Predators have evolved a variety of novel mechanisms for efficient prey location that rely on specific sensory modalities. Strike-induced chemosensory searching (SICS) is a behavior pattern common across squamate reptiles (snakes and lizards) where a series of specific searching behaviors are activated in the predator following the envenomating strike and immediate release of prey. Of all squamates, rattlesnakes (Crotalus spp.) have been studied most extensively for their SICS behavior, but field documentation of such behaviors is sparse and often lacking in detail. Our study took advantage of a wild population of Timber Rattlesnakes (Crotalus horridus) in the Ozark Mountains of northwest Arkansas. Individuals were implanted with radio transmitters as part of a larger study on the effects of supplemental rodent prey on the physiological ecology of C. horridus. From these supplemental feeding trials, we filmed n = 10 successful episodes of SICS as rattlesnakes (n = 7) struck, released, and relocated rodent prey. All rattlesnakes exhibited the typical phases of SICS (quiescence, searching, trailing), and though the duration of each phase did not differ, rates of tongue-flicking (RTF) and breathing significantly increased from quiescence to trailing. We noted rapid, shallow ventilation patterns in the rattlesnakes, burst-like ventilation (BLV), and propose that BLV functions to surveil volatile chemical cues in the environment. Rates of tongue-flicking are well known proxies for measuring vomerolfaction in squamates, and we suggest BLV may similarly serve as a proxy for estimating rates of olfaction. The short cycles of air exchange we quantified as BLV flush air across the olfactory epithelium and thus could serve to detect volatile chemical cues. Quantification of BLV may enable researchers to capture more information about the sensory processes involved in squamate foraging behavior.