After a wonderful trip to Puerto Rico for the recent Thermal Ecology meeting mentioned here on Anole Annals and so heavily attended by anolologists, we had the opportunity to visit some of the natural forests that the country had to offer.
Riparian habitat in the forest by the El Verde Field Station, Puerto Rico
Whilst in El Verde National Park, we were regaled with stories of local Anolis advancing to the ground and using riparian habitat despite what their ecomorph classification might suggest. Given the recent AA interest in aquatic anoles (1,2,3), I thought a short note on this may be appreciated. Apologies for the deceivingly melodramatic title; alas it was literal, not figurative.
An adult male A. evermanni perched on a boulder surrounded by fast flowing water
Anolis evermanni, a trunk-crown ecomorph, has been known to use boulders along one of the streams for the past two decades or so. With great anticipation, whilst marching through the forest spotting copious numbers of Anolis gundlachi, we were en route to our final destination to find out! Upon reaching the stream, which incidentally offered some beautiful tropical scenery accompanying the break in the canopy, we were not disappointed to find A. evermanni dotted all around the waterway!
I assure you there is an anole there – this wasn’t just an excuse for a rest…!
An adult male A. evermanni displaying
Back in 1990, Jonathon Losos postulated that this shift in microhabitat from trees to boulders forced a change in locomotor strategy. Whilst anoles are able to travel continuously in a forest, by travelling down a tree, along the ground and then up another, the structural heterogeneity presented by these riparian boulders meant that jumping needed to be more commonly adopted. He posited that the difference in thermal strategy of A. evermanni and A. gundlachi, a heliotherm and a thermoconformer respectively, would affect their likelihood of using these boulders along the highly sunny stream. Although A. gundlachi were observed present along the shaded edge, they rarely ventured further out. After some thought on site, this prompted a brief hypothesis by a couple of us; when the sun began to disappear, would the larger A. gundlachi displace the A. evermanni on the boulders?
This may take some imagination, but that blur to the right of the central vine – I assure you that’s a boulder-loving A. gundlachi!
After a couple of hours of enjoying the forests of El Verde, we returned to the field station. As we were leaving and the sun was beginning to calm, I spotted our first A. gundlachi out on a stream boulder followed shortly after by a handful of A. stratulus. This would seem to offer a cool behavioural research opportunity for someone that enjoys sitting in the sun by a river watching lizards…(can’t be that bad a gig, can it?).
A. stratulus also getting in on the action
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Robert Powell
Did you observe any anoles taking to water either voluntarily or when disturbed?
James Stroud
I didn’t, all anoles that I pursued continued to use the rocks. However there were a lot of lizard people disturbing a lot of lizards, I’m sure quite a few of them read AA – maybe someone else witnessed this?
Sean Giery
Cool! I remember reading about this in Douglas Reagan’s chapter in “The Food Web of a Tropical Rainforest”. It always seemed a strange caveat, but it definitely says a lot about ecological opportunity. Nice update, thanks!