Little is known about the ecology and natural history of South American anoles. This study reports the results of a variety of different studies on several relatively common species of Ecuadorian Anolis. In part I, habitat use and population density are compared among three species of Anolis that occur in sympatry at a number of sites in Ecuador. The three species—A. chloris, A. festae, and A. peraccae—are roughly the same body size. These species perch primarily on tree trunks, and A. chloris perches substantially higher than the other two species, which are similar in perch height. Large differences from one year to the next were observed both in mean perch height and in population densities.

In Part II, natural history, growth rates, and population densities are reported for two little known Anolis species, A. bitectus and A. gemmosus. Although the two species are from nearby regions and are similar in microhabitat use, they show more differences than similarities in most aspects of their biology. The species have similar ranges in active body temperatures, but A. bitectus is thermally passive, whereas A. gemmosus appears to thermoregulate. Populations of A. gemmosus tend to remain constant through time, whereas A. bitectus undergoes moderate population fluctuations. Both species exhibit little sexual size dimorphism, but in A. bitectus females are larger, and in A. gemmosus males are larger. Anolis bitectus has a fairly high characteristic growth rate, whereas that of A. gemmosus is quite low.