In the present work about Peltocephalus dumerilianus ("big-head" Amazon turtle), an aquatic chelonian inhabiting the Am-azon basin, the sex composition was analyzed by the capture-recapture method in two tributaries of the Rio Negro, and mor-phometric parameters were compared individually and by sex. By means of a mathematical model the populational abundance was calculated. Also, through telemetry, the occupied home range was calculated according to sex, and differences among populations were established
