Anolis evermanni is considered a "trunk-crown" species. The species in this ecomorph tend to live, as you might guess, on tree trunks and upper branches. They are graceful and agile, hunting bugs by moving stealthily through the branches. They are typically green, to match the leafy background up in the trees. The only native U.S. anole, Anolis carolinensis, is also considered a trunk-crown species. If you want to learn more about ecomorphs and anoles in general (and who doesn't?), you should read Jonathan Losos's most excellent book Lizards in an Evolutionary Tree: Ecology and Adaptive Radiation of Anoles.
After such a highfalutin introduction, I should note that this particular lizard was not on a tree at all, but on the handrail of a bridge at El Yunque National Forest's visitor center.
- Caribherp's list of reptiles and amphibians of each Caribbean island
- Schwartz, A., Henderson, R. W. 1991. Amphibians and Reptiles of the West Indies: Descriptions, Distributions, and Natural History
- Schwartz, A., Henderson, R. W. 1985. A Guide to the Identification of the Amphibians and Reptiles of the West Indies Exclusive of Hispaniola