In advance of our trip out to Swan Island, I’ve come to Roatan, one of the Bay Islands just off the coast of Honduras, to check out its anole fauna. Of particular interest is the mixture of island and mainland faunas: A. allisoni¸ a trunk-crown member of the carolinensis group, somehow found its way here from Cuba, whereas A. roatensis (nee lemurinus) represents the mainlanders. And, as a bonus, A. sagrei is here, too, apparently introduced. I’m looking forward to seeing how they mix it up.
Things didn’t get off to a good start yesterday when I arrived mid-afternoon. It was very overcast and drizzly, and the temperature probably barely topped 70. Brrr! With more of the same forecast for today, I was not optimistic.
But although it looked like it was on the verge of raining all day, it held off until after dark. The sun was in and out, and so were the lizards. My expectation was that the balance of color would be like it is in other places where carolinensis and sagrei group anoles co-occur: lots of brown anoles on the ground and low on trees, bushes and buildings, and a small to moderate number of greens at eye level up to the treetops.
I couldn’t have been more mistaken. Green anoles were seemingly everywhere—as thick as anywhere I’ve ever been. And the browns? I saw three. The greens were on the buildings, on the fences, in the bushes up the trees, even doing their best grass-bush anole imitation along the roadside. They were everywhere, except one place: the ground. And therein lies the explanation for this green:brown inversion. There were brown lizards in great abundance—at least in open sunny localities—but although they skittered about and occupied the same place, they weren’t anoles. Rather, they were these fellows.
Brown basilisks, Basiliscus vittatus. Many of them were sagrei-sized, and if you weren’t paying attention, their abundance might have convinced you they were anoles. But then there were the bigger fellows, not as abundant, but plenty of them. My hunch is that they’re why brown anoles haven’t gotten much of a foothold. The little guys compete with the sagrei, and the bigger ones eat ‘em. I speculated earlier this year about interactions between basilisks and introduced A. cristatellus in Costa Rica—there, they seemed to coexist and cristatellus was doing fine. Here, I think the story is different. Of course, brown basilisks have also been introduced to Miami, where they coexist with sagrei, so maybe I’m barking up the wrong tree, but the great abundance of basilisks, living exactly where you’d expect to see the sagrei, seems too much of a coincidence to me.
Whatever the cause, the absence of sagrei seems to have given allisoni the green light to go crazy. They’re enormously abundant and use many off-the-ground habitats—fences, buildings, etc.—where you’d expect to see sagrei. At least in open places, like hotels, they are very common from 1-2 meters in height, or even lower. In more forested areas (and remember, this is based on one day’s observations, and the forested areas were visited in the afternoon), they seem mostly high up, generally in sunny spots. I was particularly struck that they were very common in the thick grass, while at the same time as high up in the tree as I could see them. Those of you who live with green anoles in other places (I’m thinking of certain Georgians and Little Caymanians), I’d appreciate your thoughts. Does this seem different from your abundant greens?
Now, as for the other native anole, A. roatensis, today I was shut out. They’re supposed to be in forested areas, and I have a hot lead for a spot tomorrow, so hopefully will have more to report then.