Hang in there: comparative arboreal prey-handling in boa constrictors and ball pythons

Snakes are a diverse group of reptiles, having colonized almost every environment on the planet. Multiple snake lineages have independently evolved semiarboreal or completely arboreal species. As snakes lack limbs, the challenges of moving and feeding in an arboreal environment are numerous. Here we compare the prey-handling ability of the semiarboreal boa constrictor to the terrestrial ball python in a simulated arboreal context. Snakes were allowed to strike at rodent prey and attempt to swallow that prey while suspended. Boa constrictors were successful in feeding, using a complex suite of behaviors to maintain their position and manipulate their prey. Boa constrictors positioned rats so that swallowing occurred in the direction of gravity, and would use loops of their body to support the rat during swallowing. Ball pythons were frequently not successful in feeding, lacking the complex behaviors that boa constrictors frequently employed. Ball pythons would attempt to swallow, but in the majority of feeding attempts were ultimately unsuccessful. These unsuccessful feeding attempts were typically characterized by the ball pythons hanging upside-down, trying to swallow the prey against the direction of gravity. We suggest that behavioral modifications to feeding encouraged successful invasion of arboreal habitats, but more sampling of snake diversity is needed to explore the range and types of feeding behaviors that arboreal snakes employ.