Scaredy Lizards: Differences in Escape Behavior in Two Jamaican Anoles

Anolis grahami and A. lineatopus

Research on the escape behavior of lizards has become somewhat of a cottage industry in the last two decades, with scores, if not hundreds, of papers examining the effect of factors such as temperature, concealment, and crypticity.  Probably the most important early paper in this area (and perhaps the first period) was Stan Rand’s study of the effect of body temperature on flight initiation distance of Anolis lineatopus.  This work—conducted on the grounds of the University of the West Indies in Mona (a suburb of Kingston), Jamaica—reported that lizards with lower body temperatures fled at greater distances from an approaching predator.  Rand speculated that this pattern resulted because warmer lizards could run faster, setting the stage for the pioneering work on the effect of temperature on sprint locomotion by Ray Huey, Al Bennett, and others.

More than four decades later, Bill Cooper returned to the scene of Rand’s work to further study the escape behavior of A. lineatopus and its relative A. grahami.  Following the method used by Rand and many since, Cooper walked directly toward lizards at a constant pace and noted how far away he was when they fled, as well as the manner in which they escaped.  Although the two species differ in habitat use, A. grahami being more arboreal, escape behavior was very similar.  In both species, lizards tended to escape by running up trees, often by moving to the far side of the tree (termed “squirreling” by many anole aficionados); lizards initially perched lower in the vegetation tended to initiate escape at greater distances; and lizards in areas with greater human activity appeared to be habituated to the presence of people and delayed escape until the faux predator was relatively close.

None of these results is surprising; rather, they agree quite closely with work on other anoles and other types of lizards.  Cooper makes an interesting observation that anoles that flee to the ground, such as grass-bush anoles, show an opposite pattern, fleeing at greater distances when they are perched higher in the vegetation.  This, of course, makes sense because the higher they are, the further they are from safety, the opposite of the relationship that occurs in species that flee upward.  As Cooper notes, more comparative work on other species, both more types of ecomorphs and species from other islands, could prove instructive.  In addition, studies using non-human predators would also be welcome to establish the extent to which behavior elicited in response to approaching humans is representative of how anoles respond to their natural predators.  Other studies have used snake or bird models to study anole escape behavior.  In this paper, Cooper explains why he and others use humans for these tests—ease and repeatability of methods are certainly major advantages.  Nonetheless, research on other types of predators would be an interesting avenue for future work. 

Finally, Anole Annals awards a booby prize to the copy editor of this journal for the unique distinction of having a typo in the first line of the abstract (“fight” instead of “flight”) and what appears to be a sentence fragment that was supposed to have been deleted as the first words of the article itself.

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Jonathan Losos

Professor of Biology and Director of the Living Earth Collaborative at Washington University in Saint Louis. I've spent my entire professional career studying anoles and have discovered that the more I learn about anoles, the more I realize I don't know.

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