American alligator

• 1. Introduction

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  The American alligator, Alligator mississippiensis, can make the surface of a pond appear to sprinkle. When a male bellows, infrasound from his roar sets the water above and beside his back jumping. Observers call this the water dance. Whole choruses of alligators bellow in B flat, at 58.27 hertz, and people who have heard them say the roar is felt more than heard. Tuba players, sonic booms and large aircraft have all set such choruses off. The animal's name comes from the Spanish el lagarto, meaning the lizard. This large crocodilian lives across the Southeastern United States, and its habits still surprise researchers. How big can one grow, and what does it eat? What does it build, and how does a mother raise her young? And how did hunting push the species so close to the edge, and what brought it back?

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• 2. Giants and Averages

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  In 1890, Edward McIlhenny shot a male alligator in Louisiana and reported its length as 5.84 metres. The animal was too massive to move, so it was left on a muddy bank after measuring. No specimen was kept. If the figure was right, the alligator would have weighed about 1000 kilograms, but the claim remains unverified.

  Modern records are smaller and better documented. An alligator that was 4.5 metres long and weighed 458.8 kilograms, killed in Alabama, was declared an SCI world record in 2014. The largest verified in Florida between 1977 and 1993 measured 4.23 metres and weighed 473 kilograms.

  Typical adults are far smaller. Most mature males reach about 3.4 metres and weigh up to 360 kilograms. Mature females are usually around 2.6 metres, with a body weight up to 91 kilograms. In Newnans Lake in Florida, adult males averaged 2.47 metres and 73.2 kilograms. Alligators from the northern edge of the range, such as southern Arkansas, Alabama and northern North Carolina, tend to stay smaller.

  Big males are scarce for another reason. Female alligators survive better when young, and many populations are made up mostly of immature animals or young breeders. The size gap between the sexes is also modest. In saltwater crocodiles, mature males are nearly twice as long as females and at least four times as heavy.

  Reptile literature long claimed that crocodilians never stop growing. A mark-recapture study at the Tom Yawkey Wildlife Center in South Carolina, running from 1979 to 2015, found growth ending at 43 years for males and 31 years for females. Alligators typically live to about 50, and possibly beyond 70. Males reach sexual maturity at around 11.6 years, and females at around 15.8.

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• 3. Jaws and Armor

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  Between 74 and 80 teeth line the jaws of an adult American alligator. Hatchlings start with small, needle-like teeth and narrow snouts. As the animal grows, the teeth become much more robust and the snout broadens. These changes track a shift in diet, from fish and insects to turtles, birds and other large vertebrates.

  Alligators lose and replace their teeth about once a year. Over a long life, one animal can go through more than 2,000 teeth.

  The bite is the famous part. Adult alligators held the record for the strongest laboratory-measured bite of any living animal, at up to 13172 newtons. The same laboratory later measured a greater force of 16414 newtons in saltwater crocodiles. Bite force rises as the alligator grows, and males and females of equal size bite equally hard.

  The muscles that open the jaw are quite weak. A captured alligator can have its jaws held shut by hand or by tape.

  People often mistake the alligator for the American crocodile, and the fourth tooth settles the question. When an alligator closes its mouth, the upper jaw covers the lower teeth and that fourth tooth disappears into a pocket. The snout is also a broad U shape, and the jaws overlap.

  Color helps too. Adults may be olive, brown, gray or black, with cream-colored undersides, and their blackish scales are among the darkest of any modern crocodilian. Albino alligators lack melanin, are almost impossible to find in the wild, and survive only in captivity because the sun and predators would quickly overwhelm them.

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• 4. Range and Winter

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  From the Lowcountry of South Carolina to Everglades National Park in Florida, and west to South Texas, the American alligator holds a belt of wetlands. Ten states have populations, from North Carolina and Georgia to Oklahoma and Texas. Louisiana has the largest alligator population of any state.

  The animal prefers fresh water: swamps, streams, rivers, ponds, lakes and wetland prairies. Salt is a problem, because the salt glands on its tongue do not function. Golf courses are a surprising favorite, since they offer abundant water and a steady supply of fish and birds. One lone alligator lived for more than 10 years in a river north of Atlanta, Georgia.

  Cold is where alligators beat their cousins. An American crocodile would succumb and drown in water at 45 degrees Fahrenheit or less. An alligator can sit in such water for some time without any sign of discomfort. When the water begins to freeze, alligators enter brumation. They push their snouts up through the surface, breathe above the ice, and can stay that way for several days. No other crocodilian is found farther from the equator.

  The range is creeping north. Alligators have naturally expanded into Tennessee and established a small population in the southwestern part of that state. Virginia lost its alligators, though vagrants from North Carolina occasionally wander into the Great Dismal Swamp. In 2021, a hunter killed an alligator with a crossbow in Calvert County, Maryland, near Chesapeake Bay. Other reports from that region are believed to involve escaped or released pets.

  Researchers are also watching juveniles in saltier water. Young alligators have been shown to change habits such as basking and moving between habitats, rather than adapting physically, to avoid dehydration.

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• 5. The Opportunist's Table

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  Hatchlings begin on insects, insect larvae, snails, spiders and worms, along with small fish and frogs. Adults sit at the top of the food chain and eat almost anything that lives in or comes to the water. The menu includes largemouth bass, spotted gar, yellow mud turtles, cottonmouths, common moorhens and feral wild boars. Adults also hunt on land, up to 50 metres from the water, ambushing animals on trailsides and road shoulders.

  Their teeth can grip but not tear. Digestion depends on the gizzard and on swallowed rocks that grind food. Alligators have also been found with bottle caps in their stomachs. Four documented incidents show them killing and eating sharks and rays, including bonnetheads, lemon sharks, Atlantic stingrays and nurse sharks.

  Diets vary by place. In Lake Apopka, fish made up 90 percent of the food and shad dominated. In Lake Woodruff, the figure was 84 percent, mostly bass and sunfish. In East Texas, adults ate mammals, reptiles and amphibians about as often as fish.

  In 2013, reports confirmed that alligators eat fruit, including wild grapes, elderberries and citrus taken straight from the trees. Stomach contents held seeds from 34 plant families and 46 genera. That suggests alligators may spread seeds across their habitat.

  Some observers have seen what looks like teamwork. In one account, about 60 alligators formed a semicircle and pushed fish toward the bank. Pushers and catchers took turns, and the scene repeated the next day.

  A more startling claim is tool use. Alligators in two Florida zoos and some Louisiana parks were documented balancing sticks on their heads, apparently to lure birds seeking nest material. A three-day experiment published in 2019, using 30 to 35 sticks per square metre near captive populations, failed to show the behavior was more common near bird rookeries. Its purpose, if any, remains ambiguous.

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• 6. Pond Builders

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  In the flat Everglades, alligators dig small ponds known as alligator holes. They also tunnel into banks and make dens above the waterline with access to air. These habits have earned the animal the label of keystone species.

  During the dry season, the holes keep water when little else does. Fish and other aquatic animals shelter there, and they become the seed stock for future populations. Soil piled up during digging, along with nests built around a hole's rim, gives other reptiles drier ground and gives flood-sensitive plants a place to grow. Holes in limestone cypress swamps tend to be large and deep. Those in marl prairies and rocky glades are usually small and shallow.

  Alligators also shape the food web. Nutria were brought from South America in the mid-20th century, and their numbers have exploded into the millions. They damage coastal marshes, and Louisiana has paid a bounty to reduce them. Large alligators eat nutria heavily, and may keep them from spreading east into the Everglades. Because hunting takes the biggest alligators first, harvest rules might need to change to protect that service.

  Burmese pythons have recently settled in Everglades National Park. Alligators eat pythons, and pythons occasionally eat alligators, yet no net harm to alligator numbers has been seen. Substantial alligator populations may help keep python numbers low and stop them moving north.

  Because alligators respond sharply to changes in hydrology, salinity and productivity, scientists treat them as indicators of Everglades restoration success. Wading birds seem to like their company. Alligators keep predatory mammals away from island rookeries and eat spilled food and fallen chicks. Birds nest even at crowded tourist stops such as the St. Augustine Alligator Farm in Florida.

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• 7. Mothers and Nests

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  A female alligator lays 20 to 50 white eggs, each about the size of a goose egg, in a nest of vegetation, sticks, leaves and mud. She covers them with more plant matter, which heats as it rots and keeps the eggs warm. Nile crocodiles, by contrast, lay their eggs in pits.

  Nest temperature decides the sex of the young. Eggs kept below 88.7 degrees Fahrenheit or above 94.1 degrees produce females, and those between the two produce males. Nests on levees run warmer and yield males, while cooler wet-marsh nests yield females.

  The mother stays near the nest throughout the 65-day incubation, driving off intruders. Her young call from inside the eggs, and their yelping can be heard just before hatching begins. She digs them out and carries them to the water in her mouth.

  Newborns look like tiny adults, banded in yellow that serves as camouflage. They gather in pods, guarded by their mother and kept in touch by yelping. Such parental care is rare among reptiles, and it can last up to 3 years after birth. Eventually mothers grow more aggressive toward their young, which encourages them to disperse. Young alligators grow 3 to 8 inches a year and reach adulthood at about 6 feet.

  The early years are dangerous. Young alligators fall prey to herons, egrets, otters, snakes, raccoons, large fish and other alligators.

  Parasites are another constant. In a 2016 study in Texas, every alligator collected was infected, with at least 20 different parasite species, including lung pentastomids, gastric nematodes and intestinal helminths.

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• 8. Recovery and Reputation

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  In 1967, the American alligator was listed as endangered under a law that preceded the Endangered Species Act of 1973. Hunting and habitat loss had been unsustainable from the 19th century into the mid-20th century, and the species' survival was in doubt. The United States Fish and Wildlife Service and southern state agencies worked together on its recovery. States began monitoring their populations to make sure numbers kept climbing. In 1987, the animal was removed from the endangered list as fully recovered. Today the IUCN rates it Least Concern.

  Trade is still regulated. The Fish and Wildlife Service watches the market so that endangered crocodilians cannot be passed off as American alligators, and the species sits in Appendix II of the CITES treaty.

  Living beside a recovered predator has costs. Florida recorded 257 attacks on humans from 1948 on, about five a year, with an estimated 23 deaths. Alligators killed 12 people between 2001 and 2007, and three Floridians in less than a week in May 2006. At least 28 fatal attacks have occurred in the United States since 1970. Murky water raises the risk of mistaken identity, and even treated bites can end in fatal infection.

  People also profit from alligators. Farming is a growing business in Georgia, Florida, Texas and Louisiana, which together produce about 45,000 hides a year. Hides of 6 to 7 feet have sold for $300 each, and some 300000 pounds of meat are produced annually. Alligator wrestling has drawn crowds since the late 1880s. It began with the Miccosukee and Seminole tribes as a way to get food, before becoming a tourist draw that animal-rights activists criticize.

  The alligator is the state reptile of Florida, Louisiana and Mississippi. The University of Florida's teams have been the Gators since 1911. In 1908, a printer made a spur-of-the-moment decision to put an alligator emblem on a shipment of the school's football pennants.

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