Life at the river's edge: ecology of Kentropyx altamazonica in Brazilian Amazonia

The teiid lizard Kentropyx altamazonica was studied at two localities in th e Brazilian Amazon region, one in Amazonas (Rio Ituxi) and the other in Ron donia (Rio Formoso). This lizard is linearly distributed along water course s, where it carries on most activities in well-lit, warm microhabitats. Act ivity does not occur on days with cloud cover. Late morning and midday acti vity predominates on sunny days. Body temperatures of active lizards were 3 5.9 +/- 0.37 degreesC (mean +/- SE) and were higher than substrate or air t emperatures at the point of capture and higher than overall temperatures in the habitat. Although a variety of prey types are eaten, spiders, grasshop pers and crickets, roaches, and insect larvae dominate the diet. Larger liz ards eat larger prey but also include small prey in their diets. Absolute a nd relative prey sizes were greater for lizards at the Rio Ituxi than for t hose in Rondonia, but lizard stomachs were equally full, suggesting that pr ey types available varied between sites. Males reach larger body sizes than females and have relatively larger heads. Although K. altamazonica is simi lar in ecology to other Amazonian Kentropyx species, it is more closely ass ociated with water than the others.