American Alligator


ORDER: Crocodilia

FAMILY: Alligatoridae

GENUS: Alligator

SPECIES: mississippiensis

DESCRIPTION:
Broadly rounded snout distinguishes it from crocodiles. Fourth tooth on each side of lower jaw is hidden when mouth is closed. Young are black with yellowish cross-bars. Mature alligators are coal black when wet, dark gray when dry. Males are 11 to 12 feet long and weigh 450-550 pounds. Females are no longer than 9 feet and weigh about 160 pounds. Record length is 20 feet.

GEOGRAPHICAL RANGE AND HABITAT:
North Carolina to Florida Keys and west to central Texas. Lacking the salt-removing glands found in crocodiles they live in fresh water swamps and waterways only. When given protection, alligator populations rebound and soon reoccupy areas where they have long been absent.

DIET:
Large stomach. Carnivorous. Eats fish, snakes, frogs, turtles, birds, and mammals such as muskrats, deer and cows. Big animals are dragged underwater and drowned and then torn to pieces. They are very efficient metabolically; even a big alligator can get by on about 50 pounds of food a year. Eats little or nothing from early October to late March. Feeds heavily during summer to store fat. Newborn starts feeding at once, eating small fishes and water insects.

LIFE CYCLE/SOCIAL STRUCTURE:
Female builds nest of vegetable debris 4-7 feet in diameter and 2-3 feet high. Courtship begins in April. Mating takes place in water after courtship displays by males. One display, known as the "water dance" is characterized by "fizzing" water around a male's torso, produced by aloud subsonic call. Female constructs a nest of rotting vegetation and lays about 45 hard-shelled white eggs slightly larger than hen's eggs from late May through June. Nine week incubation. Female guards nest until babies call, then tears the nest open and cracks unhatched eggs with her teeth. She takes them to water and often remains with them. Young are about 9 inches at hatching, weighing 2 ounces. Growth is rapid: one foot in length for each of the first six years. Young alligators are preyed upon by others of their kind and by large fish, turtles, snakes, herons, raccoons, and black bears. They probably live 50-60 years.

SPECIAL ADAPTATIONS:
All alligators bask, smaller ones most frequently. They hunt and feed at night. In winter, they bury themselves in mud, go into deep burrows or remain resting underwater with their nostrils above water and their breath keeping an air hole in the ice. Alligators can withstand cold better than crocodiles. Internal temperature may drop to 5 deg C. (41 deg F) from a temperature usually around 33 deg C. (91 deg F). American Alligators are the best vocalizers of the crocodilians. Adults have a throaty, bellowing roar with great carrying power. When alligators congregate in breeding groups in early spring, bellowing choruses can last from ten minutes to half an hour. Low growls are used during aggressive interactions. All sizes hiss when approached by an intruder. Female grunts like a pig in calling her young. Hatchlings and juveniles use a variety of grunts in many social situations. They also vocalize with infrasound, below the range of human hearing.

INTERPRETIVE INFORMATION:
The name alligator comes from the Spanish el laggard which means "the lizard". Muscles that close jaws are very strong, measured to be about 3.5 metric tons, but once shut a man can easily hold them closed with his bare hands. Alligators are grown on ranches in the U.S. as a commercial venture. How high an alligator floats and how fast it swims can act as social signals to others.

OUR ANIMALS:
5 Males.Our oldest male (born around 1963) came here from the San Jose Zoo in 1965. The other 4 came here from Florida in 2005.

STATUS IN WILD:
Crocodilians have had little competition in their niche as amphibious predator and have had 200 million years of success. However, over hunting by humans has caused some species to be in danger of extinction. The American Alligator was once considered endangered, but after protection populations have recovered and hunting is now permitted in some states. In 1989 this alligator was listed as "not at present endangered". On CITES Appendix II (1997). The U.S. Fish and Wildlife service has it listed as threatened in its 1997 listing.

BIBLIOGRAPHY:

  1. Alderton, David, Ed. 1991. Crocodiles and Alligators of the World, Facts on File, NY, pp. 69-71, 124-129.
  2. Ross, Charles, Ed. 1989. Crocodiles and Alligators. Facts on File, New York., pp. 50, 61, 106, 127, 220.
  3. Vanishing Species. 1974. Time-Life Books, New York, p. 252.
  4. Wolkomir, Richard and Joyce. 1996. "Alligator Serenade" in Wildlife Conservation, Jan/Feb 1996.

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