Breeding takes place during the night, in shallow waters. Females usually initiate courtship during peak activity. When males (bulls) wish to attract females, they often roar or bellow, emmitting subaudible vibrations which can be seen by the bubbles and ripples they produce. Other courtship rituals include rubbing, touching, blowing bubbles, and vocalizing. It is also common for males to raise their heads out of the water, exposing their vulnerable necks as an expression of "good intentions". It is also quite common for both partners to try and push one another underwater in an attempt to judge eachothers strength.
Alligators are not monogamous, but rather, polygynous, which means one male may service up to ten or more females in his territory. This maximizes chances for successful breeding. Male alligators are territorial animals during the breeding season, and will defend their area against other male intruders, often displaying acts of headramming and sparring with open jaws.
Mating System: polygynous
Both males and females reach sexual maturity when they are about six feet long, a length attained at about 10 to 12 years, earlier for males than females. Courtship starts in April, with mating occuring in early May. After mating has taken place, the female builds a nest of vegetation. Then, around late June and early July, the female lays 35 to 50 eggs. Some females have been reported as laying up to 88 eggs. The eggs are then covered with the vegetation nest through the 65-day incubation period.
Towards the end of August, the young alligators begin to make high-pitched noises from inside of the egg. This lets the mother know that it is time to remove the nesting material, and the six to eight inch alligator is hatched. Newly hatched alligators live in small groups, call "pods." Eighty percent of young alligators fall victim to birds and raccoons. Other predators include bobcats, otters, snakes, large bass and larger alligators. Females have been known to aggressively defend their young during these first few months and, in some cases, years. Maturity is generally reached during the sixth year.
Breeding interval: American alligators breed once yearly.
Breeding season: Breeding occurs in early May, with egg laying occuring in late June and early July.
Range number of offspring: 35 to 88.
Range age at sexual or reproductive maturity (female): 10 to 12 years.
Range age at sexual or reproductive maturity (male): 10 to 12 years.
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); oviparous
Males provide no parental care, and parental care by the female is limited to the first year of life. She is responsible for removing any vegetation covering the nest when her young are ready to hatch, and she will often bring them to water after hatching. During the first year or so she will defend her hatchlings from predators. After the first year, the female leaves her young to tend to new hatchlings of the next breeding season.
Parental Investment: pre-weaning/fledging (Protecting: Female)
- Britton, A. 1999. "Alligator mississippiensis in the Crocodilians, Natural History and Conservation" (On-line). Accessed 31 March 2000 at http://www.flmnh.ufl.edu/cnhc/csp_amis.htm.
- Ross, C. 1989. Crocodiles and Alligators. New York, New York: Facts on File, Inc..