Anole Annals

Photo by Casey Gilman, U. Mass. Amherst

In addition to performing dewlap extensions, head bobs, and pushups, many anoles raise a dorsal crest during territorial disputes. Here, two Anolis sagrei males square off. The static dorsal crest serves to modify the appearance of active pushups and dewlap extensions, perhaps making the male appear larger and more imposing. It is unclear how the crest is controlled. Jenssen notes the lag period before the crest is raised and the persistence of the crest after a territorial bout is concluded; thus, the crest may be a response to adrenaline and under the control of the sympathetic nervous system. Note the tongue extension by the top lizard.

I took the photo above while out on nocturnal hunt for twig anoles in the Sierra de Bahoruco (a mountain range in the southwest Dominican Republic).  Searching for twig anoles generally involves lots of hours spent scanning vines and twigs for narrow lizard profiles.  Can you find the twig anole in this image (click on the image for a larger version)?

Anoles fall prey to a variety of animals. Here, a male brown anole, A. sagrei, is being subdued and swallowed by a black racer (Coluber constrictor). Casey Gilman and I heard the two animals struggling while working on spoils islands in Mosquito Lagoon.

Photo by C. Gilman, U. Mass. Amherst

All of these islands have Florida-native green anoles (Anolis carolinensis) on them. Most islands also have the brown anole, an invasive species. In his Anolis Newsletter VI contribution, Nathan Turnbough found a non-random association between brown anole presence and racer presence on Mosquito Lagoon islands. He concluded that high densities of brown anoles support more racers.

Green anoles tend to become more arboreal in the presence of brown anoles. It is generally thought that direct interactions between the species, like resource competition or intraguild predation, cause this habitat shift. However, by increasing the density of predators, brown anoles may also indirectly affect green anole habitat use. The habitat shift may result from green anoles getting out of the way of ground-foraging racers – an escape to enemy free space.

Just following through on my promise to post more tongue extension photos.  This one is of two male A. stratulus in Puerto Rico engaging in a vigorous back and forth display.  Similar to the results reported by Schwenk and Meyer, this exchange occurred in the later stages of an encounter and was followed by direct physical aggression between the two males pictured.

Anole displays can get pretty intense.  My favorite feature of a really vigorous display is the lingual extension, a move that reminds me of Michael Jordan driving the lane for a dunk.  Although I’ve illustrated this phenomenon with a photo of Anolis distichus, I’ve seen many species of anoles using this move during really intense displays.  I’ll try to post more photos in the coming weeks.