Dewlap Displays in Cuban Knight Anoles (A. equestris)

While exploring the grounds of Fairchild Tropical Botanical Gardens with Janson Jones this past weekend, we extremely fortunately happened upon a large adult male Cuban knight anole (A. equestris) in full displaying swing. Despite the fact that knight anoles have an impressively large dewlap, I have often found this to be a relatively rare event, as large crown-giant species tend to display less than other smaller and more active species. This individual was displaying at a height of ~15 m, just below the fronds of a large Royal Palm (Roystonea regia). We didn’t see any other neighboring knight anoles, so were unsure if this was a directed or passive display series. In all, this lizard performed perhaps 4-5 sets of dewlap displays (each comprising of 4-5 dewlap extensions) before stopping and retreating back into the canopy.

Anoles typically follow a predictable and repeated pattern of display that gradually increases in intensity. Initially, and rather lethargically, an individual will nonchalantly raise its head and extend its dewlap without much extra effort (stage a); described below from Losos (2009).

This then escalates to include a slight body raise (stage b).

And ultimately results in a dramatic finale – in full display all limbs will be extended to raise both their body from the substrate (in this case the trunk of a palm tree) and elevate their tail (stage c). In the following picture you can see this final stage of displaying where intensity peaks – albeit in this individual with a regenerated (and rather stubby) tail.

And then the display starts to wind back down.

Using A. equestris collected from Miami, Enrique Font published a couple of classic papers in the late 80s/early 90s describing the functional morphology (pdf here) and display patterns (pdf here) of dewlap extensions in A. equestris. Specifically, Font & Kramer (1989) identified five distinct display patterns of A. equestris (see below). A couple of hypotheses exist for why a species may display a wide diversity of display patterns; for example, i) a diverse repertoire may facilitate visual communication between individuals spaced apart at varying distances (Hover & Jenssen 1976), or alternatively, ii) this diverse repertoire may faciliate non-physical resolution of agonistic interactions and therefore minimize the possibility of any escalation resulting in physical harm (Jenssen 1977).

Following dewlap displays, the lizard we were observing then did something I hadn’t particularly noticed before, and after the first display I brushed off as a quirk. However, following each set of displays, this individual would momentarily – but repeatedly – sway its head from side-to-side and continue displaying.

…before continuing into another display set.

This sideways head-swaying is described in detail by Front & Kramer (1989) as their display type A2 (see Fig above). In a follow-up paper, Font & Rome (1990) described the independent hyoid muscles associated with the different aspects of A. equestris display (i.e., vertical head-bobbing and lateral head-swaying).

Has anyone else observed this lateral head-swaying concluding dewlap displays in A. equestris? (And, if possible, has anyone managed to capture it on video?)

Check out Janson’s website (phosTracks), for some great photographs of a wide range of Floridian wildlife (including anoles!).

Some refs
– Font, E, Kramer, M. 1989. A multivariate clustering approach to display repertoire analysis: headbobbing in Anolis equestris. Amphibia-Reptilia. 10(3): 331-344
– Font, E, Rome, LC. 1990. Functional morphology of dewlap extension in the lizard Anolis equestris (Iguanidae). Journal of Morphology. 206(2): 245-258
– Hover, EL, Jenssen, TA. 1976. Descriptive analysis and social correlates of agonistic displays of Anolis limifrons (Sauria, Iguanidae). Behaviour. 58: 173-191.
– Jenssen, TA. 1977. Evolution of anoline lizard display behavior. Amer. Zool. 17: 203-215.
– Losos, JB. 1985. Male aggressive behavior in a pair of sympatric sibling species. Breviora. 484: 1-30
– Losos, JB. 2009. Lizards in an evolutionary tree: ecology and adaptive radiation of anoles. Univ. of California Press.