The wetlands of the southeastern United States almost overflow with diversity. Each river, sometimes each tributary, has its endemic catfish, map turtle and mussel species—and more. But one animal is the keystone holding all the exuberant variety together: the American alligator.
For the first time in memory, Shedd has alligators in a permanent exhibit space. You can see the eight juveniles in the Islands and Lakes gallery. Look for them piled up on a basking log, suspended horizontally or vertically in the water, or propelling themselves with serpentine undulations of a long, muscular tail—more than half their 20-inch length—while arms and legs are held flush to the body.
Alligators are found from Virginia to Texas, and from Missouri to Florida, most often in swamps, marshes and bayous, but also in lakes, rivers and streams. More than a few southern golf courses also have resident gators in their water hazards. Unlike their more southerly cousins, American crocodiles, alligators rarely venture into brackish or ocean waters, but they are more cold-tolerant for short periods.
In their daily and seasonal activities, gators alter their landscape. Their comings and goings forge channels through mud and duckweed to open thoroughfares for other animals. And the gator holes that they excavate with snout and tail for shelter can be the last source of water for fishes, amphibians, birds and mammals during a drought.
While “fish” stories abound of gargantuan gators, average lengths are 6 feet for females and not quite twice that for males. Yet tantalizing old records indicate males could reach lengths topping 19 feet. As most of the last bastions of these reptiles opened up to human settlement by the early 20th century, however, uncontrolled hunting, mainly for hides, made it unlikely that any animal would live long enough to attain such a breathtaking length again. At the same time, habitat destruction left the reptiles little refuge. The slaughter was so thorough that they were among the first animals listed under the Endangered Species Act of 1973.
Less than 20 years later, populations had rebounded so successfully that the U.S. Fish and Wildlife Service considered the American alligator fully recovered. (Alligators are still listed under the category “Similarity to a Threatened Taxon” to prevent accidental hunting of endangered American crocodiles.)
It was a close call for a species that has been around for more than 150 million years and survived the global extinction event 65 million years ago that wiped out 80 percent of animal species on Earth, including the dinosaurs.
Alligators are resilient
These apex predators are as exquisitely designed for hunting as any warm-blooded carnivore. Masters of ambush, in the water they resemble submerged logs. With just eyes and nostrils above the surface, they wait until prey swims within grab-and-gulp distance. Because alligators cannot chew their food, larger prey might need to be dismembered with shearing teeth during a fast and splashy log roll of the body.
Streamlined and subtle as a submarine underwater, a gator has an awkward walking gait on land. During a land ambush, however, it can go from zero to 15 in seconds, launching with the powerful back legs and galloping for a short distance. The element of surprise helps the heavy-bodied, cold-blooded animal overtake its prey before it runs out of energy.
Another sign of alligator resilience—and a critical one in their rebound from endangered status—is that they’re successful breeders, in large part because the females are attentive mothers. After mating, the female mounds mud and vegetation into a nest above the water line and lays 20 to 40 eggs, which she covers with more mud and leaf litter. She guards the nest during the 65-or-so-day incubation period. As the babies hatch, they utter guttural squeaks that prompt mom to gently break through the dried mud nest to release them. Then, in a behavior once thought to be cannibalism, she makes a little pouch in her mouth with her tongue, scoops up the 6- to 8-inch hatchlings a couple at a time and gently carries them to a nursery pool where she can continue to protect them. The babies stay with her for at least a year, often basking on her head or back. They will also follow her around on land like ducklings. Mom is never far, and if she hears the juveniles’ defense squeaks, she comes crashing through the underbrush to their rescue.
Alligators are advanced
Complex parental behavior is only one thing that sets alligators (and their relatives, the crocodiles, caimans and gharials) apart from the rest of the reptile clan. While crocodilians are one of the older reptile groups—only turtles and New Zealand’s tuatara are more ancient—they are the most physiologically modern, with features more similar to birds and mammals.
Alligators and their kin are unique among reptiles for having a complete four-chambered heart, a muscular septum similar to a diaphragm for more efficient breathing, and a convoluted cerebral cortex (all other reptile groups have smooth brains) associated with higher brain functions, learning and memory. During the spring, when birds are building nests, alligators have been observed to rest sticks on top of their snouts to attract feathered prey—possible evidence of tool using.
Crocodilians are also the most vocal of reptiles, capable of a wide range of communications. The alligator hatchlings’ squeaks while still in the nest are just a warmup. Like many turtles, snakes and lizards, gators issue a warning hiss, but with the volume and force of air escaping a truck tire. To attract a mate, they make a deep purring sound, and males can give off low-frequency vibrations in the water. To mark their location—either to define territory or attract another alligator—adults utter deep, far-reaching bellows not unlike a lion’s roar. They also engage in nonvocal communications: Alligators express territoriality with forceful head slaps on the surface of the water, a behavior similar to the head-bobbing of some lizard species.
Alligators—the little ones—are really cute
How can you not love a baby that’s all mouth, tummy and tail? Shedd’s year-old gators came from the AZA-accredited St. Augustine Alligator Farm Zoological Park. See if you can find all eight in the new habitat, located next to the map turtles. And while you’re there, learn more about their conservation story.
—Karen Furnweger, web editor
Are you familiar with Shedd’s other crocodilians, the dwarf caimans in Amazon Rising? And what’s the difference between reptiles and the residents of Amphibians? Find out here!