American Alligator
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 American Alligator range map |
The American Alligator (Alligator mississippiensis) is a member of the one of the three families of crocodile-like reptiles, whose members are living fossils from the Age of Reptiles, having survived on earth for 200 million years. However, the alligators can be distinguished from the crocodiles and ghavial by their head shape and color. The crocodiles have a narrower snout, and unlike the alligators, have teeth in their lower jaw which are visible even when the mouth is shut. In addition, adult alligators are black, while crocodiles are brownish in color.
As with all crocodilians, and the extinct traditional dinosaurs, alligators are of the reptilian branch known as archosaurs. Modern birds are generally viewed at present as living dinosaurs of the maniraptor group. Assuming this is correct, the birds are also archosaurs and thus alligators are far more closely related to birds than they are to lizards, snakes, turtles or the tuatara.
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Anatomy
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The American Alligator has a large, slightly rounded body, with thick limbs, a broad head, and a very powerful tail which it uses to propel itself through water. The tail has multiple uses for the alligators. They can use their powerful tails to knock down their enemies, or they can use it to lure fish when they are hungry. The tail accounts for half the alligator's length. While alligators move very quickly in water, they are generally slow-moving on land, although they can be quick for short distances. In order to adapt the aquatic life, their eyes and noses stick out of water and they have a special way to breathe. They can even open their mouths in water without water coming into their trachea.
Diet
Alligators eat almost anything, but primarily consume fish, birds, turtles, small mammals, and snails. Large alligators can take dogs and deer and are well known to kill and eat smaller alligators. Young alligators mostly feed on insects, crustaceans, snails, and fish.
Alligators frequently eat cats and dogs who get close to the water and are taken swiftly, so persons who have cats or dogs in alligator country should keep them away from any water in which adult alligators live. Despite their commonness in parts of their range into which Man has intruded, alligator attacks on humans are comparatively rare, and generally mistakes on the alligator's part; most have cause to fear humans.
Attacks on Man
Large alligators are capable of killing humans, but generally fear humans enough to avoid Man as prey, and are far less dangerous than the infamous Nile crocodile and saltwater crocodile. Even so, they should be left alone. Humans should not feed them (an illegal practice in Florida); such a practice causes them to associate humans with food, a dangerous practice with any large predator other than the dog. Alligators rarely kill humans, but alligator bites are serious injuries due to the risk of infection; contrasted to dogs (which themselves deliver very bad bites), large alligators have larger jaws with more strength and more teeth in dirtier mouths. Inadequate treatment or neglect of an alligator bite may result in an infection that causes a need for amputation of a limb. The alligator's tail itself is a fearsome weapon capable of knocking a man down.
Alligators are protective parents, and a very young alligator may have a mother nearby who protects her young by attacking anyone or anything that poses a threat.
As with any large wild predator (bears and big cats included), those alligators that develop an excessive familiarity with human behavior become extremely dangerous "problem" animals that must be either relocated or destroyed. Alligators are best appreciated at a safe distance for the protection of both persons and alligators; handling of them is best left to well-equipped and trained experts.
Range
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Today, alligators are found throughout the Southeast, from Merchants Millpond State Park in North Carolina to Texas and north to Arkansas. As during the Reptile Age, today alligators live in wetlands, and it is this vital habitat that holds the key to their continued long-term survival. Alligators depend on the wetlands -- and in some ways the wetlands depend on them. As predators at the top of the food chain, they help control numbers of rodents and other animals that might overtax the marshland vegetation.
Gator holes
The alligator's greatest value to the marsh and the other animals within it are the "gator holes" that many adults create and expand on over a period of years. An alligator uses its mouth and claws to uproot vegetation to clear out a space; then, shoving with its body and slashing with its powerful tail, it wallows out a depression that stays full of water in the wet season and holds water after the rains stop. During the dry season, and particularly during extended droughts, gator holes provide vital water for fish, insects, crustaceans, snakes, turtles, birds, and other animals in addition to the alligator itself.
Sometimes, the alligator may expand its gator hole by digging beneath an overhanging bank to create a hidden den. After tunneling as far as 20 feet (6 m), it enlarges the end, making a chamber with a ceiling high enough above water level to permit breathing. This is not the alligator's nest but merely a way for the reptile to survive the dry season and winters.
Reproduction
The breeding season begins in the spring. Although alligators have no vocal cords, males bellow loudly to attract mates and warn off other males during this time by sucking air into their lungs and blowing it out in intermittent, deep-toned roars.
The female builds a nest of vegetation, sticks, leaves, and mud in a sheltered spot in or near the water. After she lays her 20 to 50 white, goose-egg-sized eggs, she covers them under more vegetation, which, like mulch, heats as it decays, helping to keep the eggs warm. The temperature at which alligator eggs develop determines their sex. Those eggs which are hatched in temperatures ranging from 90 to 93 degrees Fahrenheit turn out to be male, while those in temperatures from 82 to 86 degrees Fehrenheit end up being female. Intermediate temperature ranges have proven to yield a mix of both male and females. The female will remain near the nest throughout the 65-day incubation period, protecting the nest from intruders. When the young begin to hatch they emit a high-pitched croaking noise, and the female quickly digs them out.
The young, which are tiny replicas of adult alligators with a series of yellow bands around their bodies, then find their way to water. For several days they continue to live on yolk masses within their bellies.
Alligators reach breeding maturity at about 8 to 13 years of age, at which time they are about 6 to 7 feet long. From then on, growth continues at a slower rate. Old males may grow to be 14 feet long and weigh up to 1,000 pounds during a lifespan of 30 or more years.
Endangered species recovery
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Historically, alligators were depleted from many parts of their range as a result of market hunting and loss of habitat, and 30 years ago many people believed this unique reptile would never recover. In 1967, the alligator was listed as an endangered species (under a law that preceded the Endangered Species Act of 1973), meaning it was considered in danger of extinction throughout all or a significant portion of its range.
But a combined effort by the U.S. Fish and Wildlife Service and state wildlife agencies in the South saved these unique animals. The Endangered Species Act prohibited alligator hunting, allowing the species to rebound in numbers in many areas where it had been depleted. As the alligator began to make a comeback, states established alligator population monitoring programs and used this information to ensure alligator numbers continued to increase. In 1987, the Fish and Wildlife Service pronounced the American alligator fully recovered and consequently removed the animal from the list of endangered species.
Although the American alligator is secure, some related animals -- such as several species of crocodiles and caimans -- are still in trouble. For this reason, the Fish and Wildlife Service still regulates the legal trade in alligator skins, or products made from them, in order to protect these endangered animals with skin that is similar in appearance, but illegal in the commercial market.
Dangers in South Florida
In South Florida, alligators face ambient temperature patterns unlike elsewhere in their range. The consistently high temperatures lead to increased metabolic cost.
Alligators in the Everglades have reduced length to weight ratio, reduced total length, and delayed onset of sexual maturity compared with other parts of their range. The reason for this poor condition is currently suspected to be a combination of low food availability and sustained high temperatures.
Two American aligators in Florida tagged by government researchers.
External link
- Everglades National Park article on the American Alligator (http://www.nps.gov/ever/eco/gator.htm)
- Federal Wildlife service page on the alligator (http://species.fws.gov/species_accounts/bio_alli.html)
- Thermoregulation of the American Alligator in the Everglades (http://sofia.usgs.gov/geer/2000/posters/thermoreg_gator/)