Foraging and Prey Handling in the Western Patch-nosed Snake (Salvadora hexalepis), and Consideration of Venom Use in Non-front-fanged Colubroid Snakes

摘要

Snakes are secretive animals; observations of foraging behavior, much less predation events, are rare and important to document. Although Western Patch-nosed Snakes, Salvadora hexalepis (Colubridae, Colubrinae), can be relatively common, representing 4-5% of snakes observed at two sites in the Sonoran Desert near Phoenix in recent surveys (Sullivan et al. 2017), foraging behavior and prey handling are poorly known. It is generally accepted that the enlarged rostral scale of S. hexalepis serves some purpose in foraging, such as facilitating digging in loose sand (Conant 1975) for eggs of squamates, a favored prey item (Rorabaugh and Lemos Espinal 2016). It is also widely appreciated that many colubrids possess oral products with toxic components (Weinstein 2015), and some of these clearly are venoms because they are actively used in subjugation of prey or self-defense (Weinstein et al. 2011), or both. Many taxa also have enlarged teeth toward the rear of the maxilla, which may or may not contain grooves, but unlike the canaliculated anterior maxillary dentition (= fangs) of viperids, elapids, and two genera of lamprophiids, do not contain a fully enclosed lumen (Weinstein and Kardong 1994; Weinstein et al. 2011).