Anole Annals

Anolis tigrinus. Photo by J. Losos.

I’ve previously posted on the surprising behavior of the Venezuelan A. tigrinus. We found them in astonishing abundance in the town of Colonia Tovar, in the mountains above Caracas. Despite their twig anole appearance and their twig anole habitat use–on twigs and other narrow surfaces–they don’t behave like twig anoles. Rather, they move rapidly and often, and seem to display a lot as well. Some Caribbean twig anoles move frequently, albeit slowly, and some display a lot, but none zip around like these guys. Moreover, we’ve seen a number of other mainland twig anoles, and they live life in the slow, slow, slow lane. So, our first day of tigrinus-watching was full of surprises. But that night, things got even more surprising, as I recently recounted in my most recent post in the Scientist at Work blog of the New York Times..

The tell-tale banded tail.

Anolis tigrinus sleeping on a stem. Photo by J. Losos.

As we walked down to the local brewhaus to grab a pizza, we casually scanned our surroundings. And as we walked by a weed patch, there was the tell-tale white blob hanging on to the end of a grass blade. It could be only one thing–an anole. In the Caribbean, this would be primo grass-bush anole habitat, but there were no grass-bush anoles here. Quick examination confirmed that it was an A. tigrinus. That’s right, a twig anole in the grass. And then as we looked around, there were more and more of them–the lot was silly with twig anoles.

The next two days, I came back during the day to look for twig anoles. Unlike in the woods where we had found them initially, the twig anoles here were hard to find during the day, even though the place was full of them at night. The few I saw were deep in the vegetation–my conclusion is that this guys are moving through the vegetation, navigating along narrow branches, stems, and grass-blades.

Which leads, of course, to the question of why in the Caribbean, grass-bush anoles use low-lying narrow vegetation in grassy, bushy  areas, while twig anoles use narrow twigs and branches up in the trees. Perhaps A. tigrinus  is just being opportunistic, taking advantage of an unoccupied habitat and moving in? Certainly a plausible explanation, but I’ve never, ever heard of a twig anole in the grass in the Caribbean. Has anyone? Not even in Jamaica, where there are no grass-bush anoles.

This in turn reminds me of the trunk-crown anoles, A. allisoni, I observed in the grass in Roatan, Honduras. If nothing else, it’s important to remember that anoles are very behaviorally flexible and adaptable. Even though they’ve specialized to different microhabitats, they aren’t so specialized that they can’t use other microhabitats when they get the chance. Crown-giant anoles on the ground are one example, but that’s another story.

In any case, A. tigrinus is a very interesting anole, and it’s great abundance would make it an excellent choice for behavioral and ecological studies.

Sweet dreams, little tiger anole. Photo by J. Losos

Female Knight anole digging nest at the base of an oak. April 2013

On my way to teach biology lab the other day, I ran into this female knight anole (actually, my buddy Zack is the one who spotted it).  She was obviously spooked by us and after snapping a few photos I backed off to see if she would continue nesting.  After a few seconds she returned to her task.  I don’t know why I imagined anoles would dig with their hind legs, but for some reason I did. However, she continued to excavate with alternating strokes of her front feet.  Unfortunately I had to run to a meeting, but when I returned a few hours later her hole was still there.  Zack had stayed behind to watch her progress and reported that she had aborted the endeavor when a bicyclist whizzed past a bit too close. The hole was about 4 centimeters deep and 5 wide into the mineral soil when she left.

Female Knight anole observed digging nest at the base of a large fig tree. Note the soil under her front claws and on her snout. Observed July 2012.

This is the second time I’ve seen nesting knight anoles in Miami.  The first was last summer when I found a very healthy looking female at the base of a fig tree.  There was dirt on her snout and a small hole where she had been.  In both cases, the nesting females were within 1 meter of a tree, and both were excavating with their front feet and possibly their snout.  Also, the dates of each observation show that there is a protracted nesting season in South Florida that includes April 10^th to July 20^th.  Such a long season explains the variable size of first year knight anoles that I find during the spring.

Here’s something you don’t see every day. More on these guys soon.

No flies on you guys–this remarkably obscure anole was quickly identified. So, what’s its claim to fame?

Well,  we have to backtrack to Anolis onca for a minute. Faithful AA readers will recall that A. onca is the only anole lacking a subdigital toepad. For this reason, at one point it was placed in its own genus, Tropidodactylus. However, in 1974 Ernest Williams described a new species in Breviora based on a single specimen found in a jar of A. onca in the Field Museum in Chicago. At that time, Anolis was characterized by having expanded scales under phalanxes ii and iii of the toe, whereas Tropidodactylus, of course, had none (phalanxes are the bones in a toe–humans have three per finger, for example). What was remarkable was that the new specimen had expanded scales under phalanx ii, the Anolis condition, but only keeled scales under phalanx iii–it was intermediate between the two, hence the specific name annectens. Here’s an image from Williams’ paper and a photograph of an annectens toe.

From Williams (1974).

Anolis annectens foot. Note the lamellae under only one toe bone. Photo by J. Losos.

The term “retrograde” comes from Williams’ paper and refers to the idea that A. annectens and A. onca illustrate a morphocline in toepad reduction–halfway gone, then all the way gone. Incidentally, recent molecular studies confirm that the two species are sister taxa.

Amazingly enough, A. annectens occurs in the same general region as A. onca, near Lake Maracaibo in Venezuela. In 2007, Tito Barros and colleagues reported in Tropical Zoology on the collection of an additional 22 specimens of A. annectens, confirming that the one individual wasn’t a freak. They also provided information on coloration, geographic distribution (it still hasn’t been found in sympatry with A. onca) and some data on ecology.

Since we were in the area any way, we decided to go and look for them after collecting data on A. onca. By “we,” I mean Tito Barros, Gilson Rivas, several students of theirs, and Rosario Castañeda. Anthony Herrel was busy back at the field lab conducting performance trials (sprint speed, bite force), and I was on assignment finding discarded cardboard boxes to make a proper racetrack.

The weather was beastly hot, about 110 degrees Fahrenheit, with no wind. Here’s what Rosario had to say:

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