Greetings to the Anole Annals community,
I love anoles and spend a lot of time wishing that I could personally observe the cornucopia of species that the world has to offer, though not being a scientist by profession and only encountering a small number of anole species in my immediate vicinity, I am limited to finding all about anoles that I can and trying my best to explain any interesting patterns that I notice, which brings me to the subject of this post.
On Jamaica, the island where I currently reside, there are seven species of anole lizards. However, only two of these, A. grahami and A. lineatopus, have an island-wide distribution and, more importantly, they are the only two which occur with great frequency in urban areas of south-eastern Jamaica, so naturally when I first began catching anoles these guys were my most frequent quarry. My surprise came while I was holding a large, freshly noosed grahami, which I soon discovered is not among the list of creatures that readily accept being caught. In addition to thrashing wildly and making several futile attempts to do whatever damage it could with its diminutive teeth, the lizard let out a high-pitched squeak, sort of like a rubber duck being stepped on; this was so surprising to me that I immediately flung the lizard away and was left to watch as he scrambled away, no doubt feeling pretty good about his completely accidental victory.
It didn’t take me a lot of searching on the web to find out that vocalizations had been recorded for other species of anoles before, and so I decided to compile a list of every species that I could find for which there was any record of them vocalizing; so, for anyone who has ever wondered, here it is:
- All the cybotoids (A. cybotes and relatives)
- A. garmani, A. valencienni, A. opalinus, A. grahami
- A. biporcatus, A. petersi, A. salvini (synonymous with A. vociferans)
- A.roquet, A. trinitatis, A. extremus
- A. chocorum
- A. chlorocyanus , A. coelestinus, A. vermiculatus, A. hendersoni
The list is immediately confounding in that there are at least three species groups up there (the grahami, hendersoni and roquet groups) in which all species are very closely related, but only some species vocalize; why is this ability popping up so inconsistently? I don’t think it has anything to do with any particular ecomorphs having more use for this ability than others as only one of the six ecomorphs is not represented, and it is also obvious that this trait is completely absent from some of the distinct lineages within Anolis (the genera proposed by Nicholson et al. 2012) while it shows up here and there in others. There are some species I suspect may possess the ability… such as A. conspersus, a close relative of A. grahami, but I have been able to find no mention or vocalization for this or any other species not listed above. I would love to hear if anyone has personally observed this for any other species (Anolis cybotes was the only cybotoid I had read about vocalizing, while all the others only came to my attention after an AA commenter gave an eyewitness testimony).
As to why this ability is present in some anoles in the first place, this seems to be a mystery. I know that a study was once conducted on A. grahami in which a few individuals were dissected and an attempt was made to identify sound producing structures, but none were found. The study also found that while the anoles vocalized while in aggressive confrontations, they did not respond to playback of these same vocalizations, at least not in the presence of visual stimuli, suggesting that these vocalizations do not play a pivotal role in anole social interactions. The effects of environment on whether an anole is able to vocalize are also probably negligent as the ability is present in all sorts of anoles, from mainland twig species living in mesic environments like A.salvini to West Indian xeric species such as A.whitemanni and all-around generalists like A.roquet of Martinique.
Then again, perhaps we are just looking too deeply into this. After all, when that anole squeaked at me I dropped him, which I’m sure is what he would have wanted to come out of that situation. Also, I have read that some anoles hiss ultrasonically when threatened or confronted; perhaps the big squeakers are just more intent on getting their point across.
Whatever the answer to this seemingly perplexing question is, I hope somebody figures it out eventually. Unfortunately I have stopped catching anoles and for the most part have stopped reading about them as well, so I probably won’t be adding any new species to the list. I hope anybody else with an interest in anoles comes across this post so they can find the full list of species. Unless there are more out there still, that is.