American Alligator: Facts, Size, Habitat and Diet

Appearance

Adult alligators are dark olive, gray or almost black above, with a cream-colored belly. Rows of bony plates called osteoderms run along the back and tail like built-in armor. The snout is broad and rounded in a U shape, and when the jaws close, the upper jaw overlaps the lower one so that most of the lower teeth are hidden. That “overbite” is one of the quickest ways to tell the two groups apart; see alligator vs crocodile for the full checklist.

The eyes, ears and nostrils sit high on the head, so an alligator can see, hear and breathe while almost completely underwater. A clear third eyelid, the nictitating membrane, protects the eyes when it dives. The front feet have five toes and the partly webbed hind feet have four. An alligator has about 74 to 80 teeth, and each one is replaced when it breaks or wears down, so an individual goes through many sets of teeth in its lifetime.

Hatchlings look quite different from adults: they are black with bright yellow crossbands that help camouflage them among reeds. The bands fade as the animal grows. White alligators exist but are extremely rare: albino individuals have pink eyes, while leucistic ones have blue eyes, and both are highly vulnerable in the wild.

How big do American alligators get?

Males grow much larger than females. A typical adult male measures 3 to 4.5 m (10 to 15 ft) and weighs about 90 to 360 kg (200 to 800 lb); very old, heavy males can reach roughly 450 kg (1,000 lb). Females rarely exceed 3 m (10 ft) and usually weigh less than 100 kg (220 lb). Alligators near the northern edge of the range, such as in North Carolina, tend to stay smaller than those in Florida and Louisiana.

Record claims need caution. The longest alligator ever reported, a male from Marsh Island, Louisiana, in 1890, was said to measure 5.84 m (19 ft 2 in), but it was never verified. Scientifically measured animals from Florida have reached about 4.2 m (nearly 14 ft) and 473 kg (1,043 lb). For a wider view of how the alligator compares with the giants of the crocodile family, see how big do crocodiles get.

Habitat and range

American alligators live in fresh water: cypress swamps, marshes, slow rivers, lakes, ponds and drainage canals. They also turn up in golf course ponds and suburban retention ponds, which makes them one of the largest animals that regularly lives alongside people in the United States.

The range runs along the coastal plain from North Carolina south through all of Florida and west through Georgia, Alabama, Mississippi and Louisiana into Texas, with smaller populations in southern Arkansas and southeastern Oklahoma. Florida and Louisiana hold the largest numbers, each with more than a million alligators.

Alligators handle cold better than any other crocodilian, which is why they live farther from the equator than any of their relatives. In winter they become sluggish and stop eating, a state called brumation. If a pond freezes, an alligator can keep its nostrils poking through the ice and wait for warmer days. What alligators cannot do well is live in salt water, because their salt glands barely work. Only in south Florida does their range meet that of the American crocodile.

What do American alligators eat?

Alligators are opportunistic carnivores that mostly hunt by ambush, waiting motionless near the surface. Their diet changes as they grow. Hatchlings eat insects, spiders, snails, crayfish, small fish and frogs. Adults take fish, turtles, snakes, wading birds and mammals such as muskrats, raccoons and, in Louisiana, the introduced nutria. Large males occasionally tackle deer or feral hogs, but most prey is much smaller than the alligator itself.

The bite is extremely strong: laboratory tests on a large alligator measured a force of about 9,450 newtons (2,125 lbf). The muscles that open the jaws, in contrast, are weak. Alligator teeth are made for gripping, not chewing, so prey is swallowed whole or torn apart by shaking and rolling. Stones are often found in alligator stomachs; they may help grind food or act as ballast, and scientists still debate their exact role.

Alligators are not strictly meat-eaters either. Studies of stomach contents have found fruit such as wild grapes, elderberries and citrus, and alligators may help spread the seeds. Some researchers have also reported alligators balancing sticks on their snouts during the egret nesting season, possibly as a lure for birds collecting nest material, but this behavior is still debated.

Behavior: basking, bellowing and gator holes

Like all reptiles, alligators rely on outside heat. They bask in the sun on cool mornings, slip into the water or shade when they get too warm, and often lie with their mouths open to shed heat. Adults are mostly solitary but tolerate each other at good basking and feeding spots, where larger animals dominate.

Alligators are surprisingly vocal. In spring, both males and females bellow with deep, rumbling roars. Males also produce infrasound, sound too low for people to hear, which makes the water on their backs vibrate and “dance”. Babies call to their mother from inside the egg, and juveniles give distress calls that bring her running.

In flat wetlands such as the Everglades, alligators clear mud and plants from depressions with their bodies and tails, creating pools called gator holes. These hold water through the dry season and become refuges for fish, turtles, frogs and wading birds, while the piled-up soil around them lets trees and shrubs take root. Because so many species depend on them, alligators are often described as a keystone species of southern wetlands.

Reproduction, life cycle and lifespan

Courtship begins in spring. In early summer the female builds a mound of plants, sticks and mud near the water and lays about 20 to 50 hard-shelled eggs inside. Heat from the rotting vegetation keeps the eggs warm for roughly 60 to 70 days. The temperature inside the nest decides the sex of each hatchling: cooler nests produce mostly females, nests around 33 °C (91 °F) produce mostly males, and very hot nests produce females again.

The mother guards the nest throughout incubation. When she hears the young calling, she opens the mound and carries the hatchlings to the water in her jaws. The babies stay together in groups called pods near their mother, often for a year or more. Young alligators grow about 7.5 to 20 cm (3 to 8 in) a year and reach breeding size, around 1.8 m (6 ft), at roughly 10 to 15 years old, depending on food and climate.

Most wild alligators that survive to adulthood live about 30 to 50 years. In zoos, some have passed 80. A long-term tagging study in South Carolina found that alligators do eventually stop growing, males at around 43 years old and females at around 31. Read more in how long do alligators live.

Predators and threats

Life is dangerous for young alligators. Raccoons dig up many nests, and floods drown others. Hatchlings and juveniles are eaten by herons, egrets, otters, raccoons, snakes, large fish and bigger alligators, so only a small fraction reach adulthood. Once an alligator passes about 1.5 m (5 ft), it has few natural enemies. In the Everglades, invasive Burmese pythons and alligators sometimes kill each other.

Today the main threats are human: drained and polluted wetlands, development along lakes and rivers, and collisions with vehicles. Saltwater creeping into coastal marshes as sea levels rise may also reduce habitat in some areas.

Conservation status: back from the brink

From the late 1800s to the mid-1900s, unregulated hunting for leather and the draining of wetlands wiped out alligators across much of their range. The species was listed as endangered in the United States in 1967. Legal protection, strict control of the hide trade and careful state management allowed populations to recover, and in 1987 the U.S. Fish and Wildlife Service declared the American alligator fully recovered.

The IUCN Red List now classes it as Least Concern. Under U.S. law it is still listed as threatened “due to similarity of appearance”, which helps protect the look-alike American crocodile from illegal trade. International trade is controlled under CITES Appendix II. Alligator farming for leather and meat is a sizeable industry in Louisiana, Florida, Georgia and Texas.

Living near people

Millions of people share their neighborhoods with alligators, and serious attacks are rare: Florida, the state with the most people and alligators side by side, records only a handful of serious unprovoked bites a year, and deaths are rarer still. Most bites happen in or at the edge of water, often around dusk.

The best protection is distance and respect. Keep well back from the water’s edge, keep children and pets away from shorelines, and swim only in designated areas during daylight. Never feed alligators; it is illegal in Florida because fed animals lose their natural fear of people. If anyone is bitten, call 911 immediately. The alligator is the official state reptile of Florida, Louisiana and Mississippi, and it is a major draw for visitors to parks such as the Everglades.

Myths and facts

Myth: alligators live in city sewers. Stories of breeding alligators under New York City are an urban legend. Occasional escaped or released pets have been found far from the species’ range, but sewers are far too cold and dark for alligators to survive long-term.

Myth: alligators never stop growing. Growth slows sharply after adulthood and, according to long-term tagging data, eventually stops.

Myth: alligators and crocodiles can interbreed. Alligators and true crocodiles belong to different families that split more than 66 million years ago, so they cannot interbreed. Africa’s giant, the Nile crocodile, is only a distant relative.