Alligator mississippiensis

Common names: American alligator, gator Range: United States

CITES: Appendix II
CSG Action Plan: Availability of Survey Data – Good
Need for Wild Population Recovery – Low
Potential for Sustainable Management – Highest
1996 IUCN Red List: Not listed (LRlc Lower Risk, least concern.)
Principal threats: Habitat destruction, environmental contamination.

Ecology and natural history

The American alligator, along with the Nile and the saltwater crocodiles, is one of the best known species in terms of behavior and ecology (see Brisbin et al. 1986, Mazzoti and Brandt 1994). Alligators are widely distributed throughout the southeastern United States. Maximum size of adult males rarely exceeds 4.5m, but historical accounts of larger specimens exist (Woodward et al. 1995).

American alligators are principally inhabitants of swamps and marshes, although they may be found in lower densities along streams, rivers, and in lakes. In some regions alligators are even known to inhabit coastal brackish water habitats.

The name “alligator” presumably derives from a corruption of the Spanish word “el lagarto.” The work of McIlhenny (1935) in Louisiana was among the first to document some of the remarkable aspects of the natural history of this species. More recent studies on alligator social behavior have demonstrated a significant degree of complexity in the species’ ability to communicate vocally (through bellows and headslaps), and visually (through a complex series of body postures) (Garrick et al. 1978, Vliet 1989). Females become sexually mature at a size of about 1.8m. Courtship and mating take place during the spring warming period, and nesting is done during the early part of the warm, wet summers. Females construct a mound nest and lay 30–50 eggs. Females open the nest and will remain near the pod of hatchlings for up to nine months. In some cases hatchlings overwinter with the female in her den.

In many areas alligators are well known burrowers and spend many of the cooler months inactive in these dens. Alligators are one of the most temperate species of crocodilians and are known to survive short spells of below freezing weather by resting in shallow water with their snouts at the surface, thus keeping a breathing hole open in the surrounding ice (Brisbin et al. 1982).

Conservation and status

The American alligator is the outstanding example of successful conservation of a crocodilian accomplished by the application of controlled use at a sustainable level. Although heavily exploited since the 1800s, and considered to be endangered in the early 1960s, populations of American alligators have responded well to management and have recovered rapidly. Extensive surveys of alligator populations have been done throughout the species’ range. Continuous monitoring of numerous localities is conducted as part of sustainable use programs in several states. Overall, alligator populations are quite healthy and, owing to expanding human populations, programs to control alligators that occur near people and dwellings (termed nuisance alligator control) are an integral part of alligator management and conservation. In some states, near the periphery of the alligator’s distribution, alligator populations are less dense and are completely protected.

Sustainable management programs have been operated in Louisiana, Florida, Georgia, Texas and South Carolina for more than a decade. Management is based on a combination of farming, ranching and direct cropping of wild adults. Farming and ranching are now being done on a large scale, particularly in Louisiana and Florida. The current stock in farms and ranches is well over 350,000 and throughout the country there are over 150 farms and ranches involved in commercial alligator production. Captive breeding (farming) produces about 20,000 hatchlings annually, i.e. about 10% of production. Commercial production of skins is highly regulated with an interlocking system of permits, licences, periodic stock inventories, ranch inspections, and rigorous tagging and export permit requirements.

In Louisiana, exploitation is primarily in the form of egg collection for ranches and a managed hunt that utilizes seasonal habitat segregation of female alligators into less accessible parts of the range to focus the hunt on males (65%–75% of harvest) (Elsey et al. 1994). Wild harvest generates 20,000–25,000 skins annually. Hunting quotas are controlled by allocating a number of tags to each licensed hunter, based on the area and quality of alligator habitat and population estimates based on nest surveys. Egg collection from private and state owned lands provides 150,000–250,000 eggs annually to ranches. Seventeen percent of the animals commercially ranched (>1.2 m long) are required to be returned back to the wild. Skin production from ranches has ranged from 88,000–150,000 per year since 1990.

In Florida, the program includes farming, hunting and nuisance alligator control, as well as egg and hatchling harvests for ranching. Controlled hunting and egg collection on both private and public lands are based on harvest allocations generated from annual population surveys and nest counts for each area. Long-term studies on harvested wetlands demonstrate that alligator populations remain stable when up to 13% of animals over 4 feet long are hunted annually or up to 50% of located nests are collected for ranching (Rice 1996, David et al. 1996). Harvest quotas based on annual monitoring of both nesting and population density is an integral part of the program. Annual production of skins in Florida is around 30,000–40,000 from all sources. A small farming program has also begun in Georgia.

South Carolina has recently initiated a program allowing controlled hunting on private lands (Rhodes 1996). In Florida, Louisiana, Georgia and South Carolina nuisance alligator control is achieved by licensed trappers who, acting under the direction of wildlife officials, respond to public complaints of alligators over 4 feet long that are considered a potential peril to people, pets or livestock. Such animals are trapped and in most instances killed and their skin and meat sold to defray costs. These programs have converted an expensive animal control program into a self-financing public service and provided important re-assurance to the public who live in alligator habitat. Alligator populations under these management programs are certainly stable or even increasing. The only remaining threat to alligators is the loss of habitat to expanding agriculture and residential development, pollution and water diversion. Sustainable use of alligators in the USA generates more than 60 million dollars annually, providing a substantial incentive to retain habitat and tolerate alligators. Fees from the regulatory system provide funding for management, regulation, enforcement and research programs on alligators.

Priority projects

Moderate priority

Investigations of population biology: The presence of healthy alligator populations, and the availability of institutional and financial resources has lead to numerous investigations of alligator biology over the years. Although the American alligator is the most thoroughly studied of all crocodilians, we still know relatively little about its population dynamics and behaviour. A better understanding of the population ecology of this species would not only benefit the management of alligators, but other large crocodilians as well. These investigations are facilitated and financed by the presence of management programs such as cropping and ranching, and are currently underway.

Research on husbandry techniques: Because of the extensive commercial ranching and farming industry in the United States, the American alligator is a prime candidate for research on captive husbandry. Captive breeding, incubation and rearing techniques need to be improved to increase the efficiency of the industry. Extensive research on these topics is currently underway, particularly in Louisiana and Florida.

American alligator, Alligator mississippiensis, Rockefeller
Refuge, Louisiana, USA. Photo by A. Yanosky.