Alligators reproduce via internal fertilization, mating at night and eventually laying 35 to 50 eggs in a small pit, which is then covered with a nest of decaying vegetation. About five times as many females are hatched as males after an incubation of 65 days, with the sex of offspring determined by temperature rather than genetic differences. The mother guards the eggs and digs them up as they begin hatching.
Despite their initial parental protection, alligators provide no food for their young and quickly abandon them after hatching, and about 80 percent are lost to predation very early in their lives. They compensate for this by laying a large number of relatively small eggs, so some survive despite the high losses.
Females are born larger than males, although males ultimately grow larger. There are many more female alligators than males, and each dominant male mates with as many as 10 different females in his territory. He attracts females with roars and rumbles, many of which are below the range of human hearing and make obvious disturbances in the water.
Alligators are similar in many respects to the closely related crocodiles. The main differences are that alligators have broader snouts, and only their top teeth are exposed when their mouths are closed.