Anole Annals

This young Anolis equestris was enjoying the recent bloom of a royal palm here in south Florida. After the freeze in 2010 there was a sharp decline in Anolis equestris (kill rate perhaps as high as 80%). The Iguana iguana population declined by 95% or more (so much for the “invasive invasion”). What has resulted from this die-off is that now I see many more of these young A. equestris. This particular specimen most likely hatched out last spring, there is also a smaller sized batch that must have hatched out in the fall. This staggered series of young animals is something I had not observed previously. Adult Anolis equestris (particularly the males) are notorious cannibals and young equestris are much slower and less agile than A. sagrei, A. porcatus, and A. distichus which often elude the sprinting attacks of equestris.

 There have been a number of citations of equestris eating birds and small rodents. Anolis equestris are opportunistic predators and will undoubtedly take fledglings if possible. I have seen mocking birds chase equestris from trees because they see them as threats, however, their fabled predatory exploits have been largely exaggerated. For nearly forty years I have made numerous field observations of A. equestris in south Florida. What I have found is that they spend their time much like their smaller anolis counterparts snapping up small arthropods. In fact, a fair proportion of their food intake isn’t even animal matter;

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Brown anole from Dust Tracks on the Web

Darwin famously pointed out that a surfeit of cats could lead to an abundance of flowers.  Janson Jones has transplanted that way of thinking to our favorite study organism, arguing that a population burst in green anoles in Florida is due to an influx of little dogs, whose ceaseless yapping and running amok has knocked brown anoles off their game, allowing the greens to proliferate. Read all about it here.

Animals and/or insects have a very weird yet amazing relationship with each other. Most of the time, a species will be wiped out without the other. When we think of our dogs, we often think about getting them the best life they can have, and we end up buying stuff from www.treehousepuppies.com or from our local pet shops. But nature does not operate that way, instead, it lets the animals and insects fend for themselves with the help of others.

And here’s what Darwin had to say:

Humble bees alone visit red clover, as other bees cannot reach the nectar. It has been suggested that moths may fertilise the clovers; but I doubt whether they could do so in the case of the red clover, from their weight not being sufficient to depress the wing petals.

Hence we may infer as highly probable that, if the whole genus of humble-bees became extinct or very rare in England, the heartsease and red clover would become very rare, or wholly disappear. The number of humble-bees in any district depends in a great measure upon the number of field-mice, which destroy their combs and nests; and Colonel Newman, who has long attended to the habits of humble-bees, believes that “more than two-thirds of them are thus destroyed all over England.”

Now the number of mice is largely dependent, as every one knows, on the number of cats; and Colonel Newman says, “Near villages and small towns I have found the nests of humble-bees more numerous than elsewhere, which I attribute to the number of cats that destroy the mice.” Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!

The fabled gray dewlapped anole. Photo by Harry Greene

Harry Greene and Jed Sparks lead a two week graduate field trip to Florida. While there, they espied the lizard shown above in the Corkscrew Swamp near Naples, FL. Here’s what Harry had to say: “Jed Sparks, the other instructor, initially said “green” after I’d told him to expect pink, and that was the first of the two we saw–I got only a glimpse of the partly protracted dewlap and no photos of that one. Second animal I got 3-4 images of separate dewlap expansions, and can say that through binos they looked pale green, but when I look at the images I see white scales and gray or green interscalar skin, not sure which! In any case, I can tell you almost exactly where I saw each of them, and they were on the same first half stretch of the ~2 mi boardwalk, in each case in well lit sites on the outer edge of swamp proper.”

Note that Macedonia in his 2003 paper referred to the dewlaps of these species as “greenish-gray.” Gray-dewlapped green anoles are known from southwestern Florida, but have been little studied. The seminal work is Macedonia’s aforementioned study, that concludes:

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Photo by Janson Jones

We’ve previously discussed how green anoles, Anolis carolinensis, are much more terrestrial in areas where A. sagrei doesn’t occur. Janson Jones, who has written on this previously, now adds a new twist–at one sagrei-less site in Georgia, they’re frolicking around in the water lilies and other aquatic vegetation. Read all about it here.

That got me thinking. Maybe this is how the famed “aquatic” anoles evolve? First you hang out on weeds in the water, next you’re jumping in for a dip?

And speaking of anoles, not only do they float, but they can swim, even those that rarely, if ever, enter the water. I’ve inadvertantly put A. sagrei into the ocean a number of times (think lizard noosing malfunction), and they just press their legs against their body and swim by undulating their tail, alligator-style. Green anoles do that, too, and I’ll bet all anoles innately can swim. I wonder what would happen if you put a crown giant in water. Anyone want to try that with their pet in the bathtub? I bet they can swim, too. So, anoles are pre-adapted (exapted, if you will) for becoming adding aquatic habitats to their repertoire.

And that leads me to one more thought in this ramble: Carl Gans published an obscure paper (Locomotor responses of Calotes to water (Agamidae: Sauria). J. Bombay Natural History Society, vol. 74:361-363, 1977) years ago about some Asian agamid lizards (Calotes) that he dropped into a swimming pool. At first they swam as described above, but then started flailing their legs ineffectually. Eventually, their head would drop below the water, they would breathe in some water, sink to the bottom and then start walking around, presumably until they would have drowned if not rescued. Doesn’t seem like they have much of a future in adapting to aquatic habitats. Similarly, if you dunk a baby duck under water (not that I’ve ever done that), they hold their breath, but baby chickens try to breathe, and things don’t go well. Take home lesson: basic motor patterns and behaviors are needed if a species is to have any hope of adapting to a new habitat. If it doesn’t have the necessary prerequisites to survive there, they have no chance of adapting. (This is, more or less, the theme of another Gans paper I stumbled across when looking for the one mentioned above).

Postage stamp for Anolis extremus, the Barbados Anole

Although advertisements on the Boston MBTA are trying to convince me that one visits Barbados for its white beaches and plush resorts, I know that the herpetofauna is the real draw!