American Alligator
| Alligator mississippiensis | ||||||||||||||
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 An American Alligator in captivity at the Columbus Zoo, in Powell, Ohio | ||||||||||||||
| Conservation status | ||||||||||||||
 Least Concern | ||||||||||||||
| Scientific classification | ||||||||||||||
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| Binomial name | ||||||||||||||
| Alligator mississippiensis (Daudin, 1801) | ||||||||||||||
 American Alligator range map |
The American Alligator (Alligator mississippiensis) is one of the two living species of Alligator, a genus within the family Alligatoridae. The American Alligator is native only to the southeastern United States, where it inhabits wetlands that frequently overlap with human-populated areas. It is larger than the other Alligator species, the Chinese Alligator.
Anatomy
Detail of an American Alligator forelimb showing the large claws and slight webbing between the toes. |
Tail is for aquatic propulsion and as weapon of defense |
The American Alligator has a large, slightly rounded body, with thick limbs, a broad head, and a very powerful tail. Males can weigh 500 lbs to over 1000 pounds. One American Alligator allegedly reached a length of 19 feet, 2 inches (5.8 meters),[1] which would make it the largest recorded. 13 to 14.5 feet (3.94 to 4.39 meters) is a more common adult size.[2] The tail, which accounts for half of the alligator's total length, is primarily used for aquatic propulsion. The tail can also be used as a weapon of defense when an alligator feels threatened. Alligators travel very quickly in water, are generally slow-moving on land and can lunge short distances very quickly. They have five toes in front and four in back.
Habitat
Today, alligators are found throughout the Southeast, from Merchants Millpond State Park in North Carolina to Texas and south to southeastern Oklahoma.
As during the Reptile Age, 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 the population 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 that inhabit 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.
Diet
Alligators eat almost anything, but primarily consume fish, birds, turtles, mammals and amphibians. Hatchlings however are restricted to smaller prey items like invertebrates. Insects and larvae, snails, spiders and worms make-up a big portion of a hatchling's diet. They will also eat small fish at any opportunity. As they grow, they gradually move onto larger fish, mollusks, frogs and small mammals like rats and mice. Sub adult alligators take a larger variety of prey; ranging from snakes and turtles to birds and moderate sized mammals like raccoons and pets.
Once an alligator reaches adulthood, any animal living in the water or coming to water to drink is potential prey. Adult alligators will eat razorbacks, deer, domestic animals including cattle and sheep, and are often known to kill and eat smaller alligators. Larger male alligators have been known to take down Florida panther and bears[citation needed], making the American alligator the apex predator throughout its distribution.
The stomachs of alligators often contain gastroliths. The function of these stones is to grind up food in the stomach and help with digestion. This is important because gators swallow their food whole. These gastroliths are also used in buoyancy control.
Despite the extensiveness of their shared habitat with humans, alligator attacks on humans are comparatively rare. Most alligators fear humans due to hunting; attacks on humans are typically a result of feeding of alligators. Once a human feeds an alligator, it expects food whenever it sees someone.
In 2002, the bite force was measured on a 12 foot alligator and the result was about 2100 pounds of force[3].
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 90–93 °Fahrenheit (32.2–33.8 °C) turn out to be male, while those in temperatures from 82–86 °Fahrenheit (27.7–30 °C) 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.The baby spends about 5 months with the mother before leaving her
Alligators reach breeding maturity at about 8 to 13 years of age, at which time they are about 6 to 7 feet (1.8–2.1 m) long. From then on, growth continues at a slower rate. Old males may grow to be 16 feet (4.85 m)[[1]] long and weigh up to 1,200 pounds (510 kg) during a lifespan of 30 or more years.
Attacks on people and Alligator safety
Alligators are capable of killing humans, but generally fear humans enough to avoid them as prey, and are far less dangerous than the infamous Nile crocodile and Saltwater crocodile. Alligator bites are serious injuries due to the risk of infection. Inadequate treatment or neglect of an alligator bite may result in an infection that necessitates amputation of a limb. The alligator's tail itself is a fearsome weapon capable of knocking a person down and breaking bones. Even though they rarely kill, they should be left alone. Untrained individuals should never feed them (an illegal practice in Florida) because an alligator that associates people with food can become a dangerous problem animal. Alligators are protective parents, and a very young alligator may have a mother nearby who will protect her young by attacking anything that comes too close. They 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.
There were only nine fatal attacks in the U.S. throughout the 70s, 80s and 90s, but alligators killed 12 people from 2001 to 2007 In May 2006, alligators killed three Floridians in four days, two of them in the same day. One victim was a jogger whose body was found in a canal on Florida's Atlantic coast; one was snorkeling in a recreation area near Lake George, in the central part of the state; another was found in a canal on the state's Gulf Coast.
When in gator country, it is a wise practice to know which lakes and rivers are inhabited by alligators and avoid being in the water with them. Alligators, sometimes quite large specimens, can even be found in less traditional waterways, such as drainage canals, ditches, golf-course ponds and storm-water retention ponds. In many areas, posted signs warn of their presence, but some alligators may be present without such a warning. Evidence of an area being inhabited by gators include alligator slides onshore (these are markers where the belly of the gator has slid down the bank into the water) and large piles of muddy sticks and foliage in spring which indicate nesting sites. Pet owners should not let their dogs and cats swim in or even approach any body of fresh water in which alligators might be or even roam; dogs and cats are easy prey for alligators. The tail deserves attention as a weapon that can knock a person down. As with any other large predator, panic only intensifies the danger. Whatever the circumstances of the confrontation, one must avoid being taken into the water in which the alligator has every advantage, including the ability to drown a person as well as intimate knowledge of the terrain.
Endangered species recovery
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.
A combined effort by the U.S. Fish and Wildlife Service, state wildlife agencies in the South, and the creation of large, commercial alligator farms saved these unique animals. The Endangered Species Act outlawed 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. The Fish and Wildlife Service still regulates the legal trade in alligator skins and products made from them.
Although the American alligator is secure, some related animals — such as several species of crocodiles and caimans — are still in trouble.
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.
Additionally, the Everglades National Park has confirmed in 2003 that there is a significant population of Burmese pythons in South Florida. These non-native snakes have sometimes won[4][5] and sometimes lost (see adjacent image)[6] in battles with alligators, but the introduction of a potential predator could have a devastating impact on endangered species as many have been found in the stomachs of these invaders.[6]
See also
- American Crocodile
- List of fatal alligator attacks in the United States by decade
References
- Everglades National Park article on the American Alligator
- Crocodile Species - American Alligator
- <http://www.sciencedaily.com/releases/2002/03/020328073615.htm>
- Gator-guzzling python comes to messy end. Published 2005-10-05 by The Associated Press, last accessed 2008-03-11.
- Butler, Rhett A. (2005-10-05 Python explodes after swallowing 6-foot alligator in Florida Everglades. Mongabay.com, last accessed 2008-03-11
- a b U.S. Department of the Interior, U.S. Geological Survey (2008-02-20). USGS Maps Show Potential Non-Native Python Habitat Along Three U.S. Coasts. www.usgs.gov, last accessed 2008-03-11.
External links
- Crocodilian Online http://www.crocodilian.com
- Thermoregulation of the American Alligator in the Everglades
- American Alligator information sheet
- [2] - click here to listen to alligator bellows and hisses
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Source: adapted by the editor from Wikipedia, the free encyclopedia; from the article "American Alligator". Image Credit.
