Sand-diving As An Escape Tactic In The Shovel-snouted Lizard, Meroles anchietae

Escape behavior often represents a balance of multiple concerns; the decision of when and how to flee is influenced by the costs associated with flight.  Lizard escape studies have identified factors influencing the choices an individual makes to optimize flight from predators.  In general, a fleeing lizard has two options: to outpace the predator, or to take refuge where a predator cannot follow.  A variety of biological and environmental factors influence which option is pursued and under what conditions.  The shovel snouted lizard (Meroles anchietae) is endemic to the sand dunes of the Namib Desert, and has the uncommon method of escaping by burying itself in the sand; an individual essentially has potential refugia under its feet at all times.  I simulated predator encounters revealing that lizards often choose to try to outrun their pursuer, sometimes for long distances, rather than dive into the sand immediately.  By tracking and measuring a lizard’s pathway after a simulated predator chase, we were able to determine that individuals generally prefer to bury themselves on the slipfaces of dunes.   Smaller and less-robust animals, and those farther from the crest or slipface, ran greater distances before sand-diving.   Lizards may choose to dive into the sand when they feel “safe” enough, or perhaps as an act of desperation only after exhaustion.   Their preference for slipfaces may be based on their ability to outrun heavier predators up the loose sand due to their fringed toes, and the ease with which the sliding sand obscures their entry point.