The American alligator (Alligator mississippiensis), sometimes referred to colloquially as a gator or common alligator, is a large crocodilian reptile endemic to the Southeastern United States. It is one of two living species in the genus Alligator within the family Alligatoridae; it is larger than the other extant alligator species, the Chinese alligator.
|Approximate range of American alligator|
Adult male American alligators measure 3.4 to 4.6 m (11.2 to 15.1 ft) in length, and can weigh up to 453 kg (999 lb). Females are smaller, measuring 2.6 to 3 m (8.5 to 9.8 ft) in length. The American alligator inhabits freshwater wetlands, such as marshes and cypress swamps from Texas to southeastern and coastal North Carolina. It is distinguished from the sympatric American crocodile by its broader snout, with overlapping jaws and darker coloration, and is less tolerant of saltwater but more tolerant of cooler climates than the American crocodile, which is found only in tropical climates.
American alligators are apex predators and consume fish, amphibians, reptiles, birds, and mammals. Hatchlings feed mostly on invertebrates. They play an important role as ecosystem engineers in wetland ecosystems through the creation of alligator holes, which provide both wet and dry habitats for other organisms. Throughout the year, in particular during the breeding season, American alligators bellow to declare territory and locate suitable mates. Male American alligators use infrasound to attract females. Eggs are laid in a nest of vegetation, sticks, leaves, and mud in a sheltered spot in or near the water. Young are born with yellow bands around their bodies and are protected by their mother for up to one year.
The conservation status of the American alligator is listed as least concern by the International Union for Conservation of Nature. Historically, hunting had decimated their population, and the American alligator was listed as an endangered species by the Endangered Species Act of 1973. Subsequent conservation efforts have allowed their numbers to increase and the species was removed from endangered status in 1987. The species is the official state reptile of three states: Florida, Louisiana, and Mississippi.
- 1 Taxonomy
- 2 Phylogeny
- 3 Characteristics
- 4 Distribution
- 5 Habitat
- 6 Ecology and behavior
- 6.1 Basking
- 6.2 Holes
- 6.3 Prey
- 6.4 Vocalizations
- 6.5 Reproduction
- 6.6 Interactions with exotic species
- 6.7 Indicators of environmental restoration
- 7 Conservation status
- 8 Relationship with humans
- 9 Culture
- 10 See also
- 11 References
- 12 External links
- 13 Further reading
The American alligator was first classified by French zoologist François Marie Daudin as Crocodilus mississipiensis in 1801. In 1807, Georges Cuvier created the genus Alligator; the American alligator shares this genus with the Chinese alligator. They are grouped in the family Alligatoridae with the caimans. The superfamily Alligatoroidea includes all crocodilians (fossil and extant) that are more closely related to the American alligator than to either the Nile crocodile or the gharial.
Members of this superfamily first arose in the late Cretaceous, about 100–65 million years ago (Mya). Leidyosuchus of Alberta is the earliest known fossil, from the Campanian era 83 to 72 Mya. Fossil alligatoroids have been found throughout Eurasia, because bridges across both the North Atlantic and the Bering Strait connected North America to Eurasia about 66 to 23 Mya.
Alligators and caimans split in North America during the late Cretaceous, and the caimans reached South America by the Paleogene, before the closure of the Isthmus of Panama during the Neogene period, from about 23 to 2.58 Mya. The Chinese alligator likely descended from a lineage that crossed the Bering land bridge during the Neogene. Fossils identical to the existing American alligator are found throughout the Pleistocene, from 2.5 million to 11.7 thousand years ago. In 2016, a Miocene (about 23 to 5.3 Mya) fossil skull of an alligator was found at Marion County, Florida. Unlike the other extinct alligator species of in the same genus, the fossil skull was virtually indistinguishable from that of the modern American alligator. This alligator and the American alligator are now considered to be sister taxa, meaning that the A. mississippiensis lineage has existed in North America for over 8 million years.
The alligator's full mitochondrial genome was sequenced in the 1990s, and it suggests the animal evolved at a rate similar to mammals and greater than birds and most cold-blooded vertebrates. However, the full genome, published in 2014, suggests that the alligator evolved much more slowly than mammals and birds.
Domestic American alligators range from long and slender to short and robust, possibly in response to variations in factors such as growth rate, diet, and climate.
The American alligator is a relatively large species of crocodilian. On average, it is the second-largest species in the family Alligatoridae, behind only the black caiman. Weight varies considerably depending on length, age, health, season, and available food sources. Similar to many other reptiles that range expansively into temperate zones, American alligators from the northern end of their range, such as southern Arkansas, Alabama, and northern North Carolina, tend to reach smaller sizes. Large adult American alligators tend to be relatively robust and bulky compared to other similar-length crocodilians; for example, captive males measuring 3 to 4 m (9 ft 10 in to 13 ft 1 in) were found to weigh 200 to 350 kg (440 to 770 lb), although captive specimens may outweigh wild specimens due to lack of hunting behavior and other stressors.
Relation to ageEdit
As with all crocodilians, and as opposed to many mammals where size eventually diminishes with old age, healthy American alligators may continue to grow throughout their lives and the oldest specimens are the largest. Very old, large male American alligators reach an expected maximum size up to 4.6 m (15 ft 1 in) in length and weighing up to 453 kg (999 lb), while females reach a maximum of 3 m (9 ft 10 in). On rare occasions, a large, old male may grow to an even greater length.
During the 19th and 20th centuries, larger males reaching 5 to 6 m (16 ft 5 in to 19 ft 8 in) have been reported. The largest reported individual size was a male killed in 1890 on Marsh Island, Louisiana, and reportedly measured at 5.84 m (19 ft 2 in) in length, but no voucher specimen was available, since the American alligator was left on a muddy bank after having been measured due to having been too massive to relocate. If the size of this animal was correct, it would have weighed about 1,000 kg (2,200 lb). In Arkansas, a man killed an American alligator that was 4.04 m (13 ft 3 in) and 626 kg (1,380 lb). The largest American alligator ever killed in Florida was 5.31 m (17 ft 5 in), as reported by the Everglades National Park. The largest American alligator scientifically verified in Florida for the period from 1977 to 1993 was reportedly 4.23 m (13 ft 11 in) and weighed 473 kg (1,043 lb), although another specimen (size estimated from skull) may have measured 4.54 m (14 ft 11 in).
American alligators do not normally reach such extreme sizes. In mature males, most specimens grow up to about 3.4 m (11 ft 2 in) in length, and weigh up to 360 kg (790 lb), while in females, the mature size is normally around 2.6 m (8 ft 6 in), with a body weight up to 91 kg (201 lb). In Newnans Lake, Florida, adult males averaged 73.2 kg (161 lb) in weight and 2.47 m (8 ft 1 in) in length, while adult females averaged 55.1 kg (121 lb) and measured 2.22 m (7 ft 3 in). In Lake Griffin State Park, Florida, adults weighed on average 57.9 kg (128 lb). Weight at sexual maturity per one study was stated as averaging 30 kg (66 lb) while adult weight was claimed as 160 kg (350 lb).
While noticeable in very mature specimens, the sexual dimorphism in size of this species is relatively modest among crocodilians. In the saltwater crocodile, for example, the females are only slightly larger at average (2.4 m (7 ft 10 in) in the American alligator, 2.6 m (8 ft 6 in) in the saltwater crocodile) than female American alligators, but the mature males, at 4.3 to 5.2 m (14 ft 1 in to 17 ft 1 in) typically, as opposed to 2.4 to 4 m (7 ft 10 in to 13 ft 1 in) expected in mature male American alligators, are considerably bigger than male American alligators and at median are nearly twice as long as and at least four times as heavy as the female saltwater crocodiles of the same species. Given that female American alligators have relatively higher survival rates at an early age and a large percentage of given populations consists of immature or young breeding American alligators, relatively few large mature males of the expected mature length of 3.4 m (11 ft 2 in) or more are typically seen.
Dorsally, adult American alligators may be olive, brown, gray, or black in color, while their undersides are cream-colored. Some American alligators are missing or have an inhibited gene for melanin, which makes them albino. These American alligators are extremely rare and almost impossible to find in the wild. They could only survive in captivity, as they are very vulnerable to the sun and predators.
Jaws, teeth, and snoutEdit
The teeth number 74–80. As American alligators grow and develop, the morphology of their teeth and jaws change significantly. Juveniles have small, needle-like teeth that become much more robust and narrow snouts that become more broad as the individuals develop. These morphological changes correspond to shifts in the alligators' diets, from smaller prey items such as fish and insects to larger prey items such as turtles, birds, and other large vertebrates. American alligators have broad snouts, especially in captive individuals. When the jaws are closed, the edges of the upper jaws cover the lower teeth, which fit into the jaws' hollows. Like the spectacled caiman, this species has a bony nasal ridge, though it is less prominent.
Adult American alligators held the record as having the strongest laboratory-measured bite of any living animal, measured at up to 13,172 N (1,343.2 kgf; 2,961 lbf). This experiment had not been, at the time of the paper published, replicated in any other crocodilians, and the same laboratory was able to measure a greater bite force of 16,414 N (1,673.8 kgf; 3,690 lbf) in saltwater crocodiles; notwithstanding this very high biting force, the muscles opening the American alligator's jaw are quite weak, and the jaws can be held closed by hand or tape when an American alligator is captured. No significant difference is noted between the bite forces of male and female American alligators of equal size.
When on land, an American alligator moves either by sprawling or walking, the latter involving the reptile lifting its belly off the ground. The sprawling of American alligators and other crocodylians is not similar to that of salamanders and lizards, being similar to walking. Therefore, the two forms of land locomotion can be termed the "low walk" and the "high walk". Unlike most other land vertebrates, American alligators increase their speed through the distal rather than proximal ends of their limbs. In the water, American alligators swim like fish, moving their pelvic regions and tails from side to side. During respiration, air flow is unidirectional, looping through the lungs during inhalation and exhalation; the American alligator's abdominal muscles can alter the position of the lungs within the torso, thus shifting the center of buoyancy, which allows the American alligator to dive, rise, and roll within the water.
American alligators are found in the wild in the Southeastern United States, from the Great Dismal Swamp in Virginia and North Carolina, south to Everglades National Park in Florida, and west to the southern tip of Texas, as well as the northern border region of the Mexican state of Tamaulipas. They are found in parts of Virginia, North Carolina, South Carolina, Georgia, Florida, Louisiana, Alabama, Mississippi, Arkansas, Oklahoma, and Texas. In 2018, several sightings of animals that had moved north into West Tennessee were confirmed. Some of these locations appear to be relatively recent introductions, with often small but reproductive populations.
They inhabit swamps, streams, rivers, ponds, and lakes. A lone American alligator was spotted for over 10 years living in a river north of Atlanta, Georgia. Females and juveniles are also found in Carolina Bays and other seasonal wetlands. While they prefer fresh water, American alligators may sometimes wander into brackish water, but are less tolerant of salt water than crocodiles, as the salt glands on their tongues do not function. One study of alligators in north-central Florida found the males preferred open lake water during the spring, while females used both swampy and open-water areas. During summer, males still preferred open water, while females remained in the swamps to construct their nests and lay their eggs. Both sexes may den underneath banks or clumps of trees during the winter.
American alligators are less vulnerable to cold than American crocodiles. Unlike an American crocodile, which would immediately succumb to the cold and drown in water at 45 °F (7 °C) or less, an American alligator can survive in such temperatures for some time without displaying any signs of discomfort. This adaptiveness is thought to be why American alligators are widespread further north than the American crocodile. In fact, the American alligator is found farther from the equator and is more equipped to handle cooler conditions than any other crocodilian. When the water begins to freeze, American alligators go into a period of brumation; they stick their snouts through the surface, which allows them to breathe above the ice.
Ecology and behaviorEdit
American alligators primarily bask on shore, but also climb into and perch on tree limbs to bask if no shoreline is available. This is not often seen, since if disturbed, they quickly retreat back into the water by jumping from their perch.
American alligators modify wetland habitats, most dramatically in flat areas such as the Everglades, by constructing small ponds known as alligator holes. This behavior has qualified the American alligator to be considered a keystone species. Alligator holes retain water during the dry season and provide a refuge for aquatic organisms, which survive the dry season by seeking refuge in alligator holes, so are a source of future populations. The construction of nests along the periphery of alligator holes, as well as a buildup of soils during the excavation process, provides drier areas for other reptiles to nest and a place for plants that are intolerant of inundation to colonize. Alligator holes are an oasis during the Everglades dry season, so are consequently important foraging sites for other organisms. In the limestone depressions of cypress swamps, alligator holes tend to be large and deep, while those in marl prairies and rocky glades are usually small and shallow, and those in peat depressions of ridge and slough wetlands are more variable.
Bite and masticationEdit
The teeth of the American alligator are designed to grip prey, but cannot rip or chew flesh like teeth of some other predators (such as canids and felids), and depend on their gizzard, instead, to masticate their food. The American alligator is capable of biting through a turtle's shell or a moderately sized mammal bone.
American alligators have been documented using lures to hunt prey such as birds. This means they are among the first reptiles recorded to use tools. By balancing sticks and branches on their heads, American alligators are able to lure birds looking for suitable nesting material to kill and consume. This strategy, which is shared by the mugger crocodile, is particularly effective during the nesting season, in which birds are more likely to gather appropriate nesting materials.
Aquatic vs terrestrialEdit
Fish and other aquatic prey taken in the water or at the water's edge form the major part of American alligator's diet and may be eaten at any time of the day or night. Adult American alligators also spend considerable time hunting on land, up to 170 ft (50 m) from water, ambushing terrestrial animals on trailsides and road shoulders. Usually, terrestrial hunting occurs on nights with warm temperatures. When hunting terrestrial prey, American alligators may also ambush them from the edge of the water by grabbing them and pulling the prey into the water, the preferred method of predation of larger crocodiles.
Additionally, American alligators have recently been filmed and documented killing and eating sharks and rays; four incidents documented indicated that bonnetheads, lemon sharks, Atlantic stingrays, and nurse sharks are components of the animal's diet. Sharks are also known to prey on American alligators, in turn, indicating encounters between the two predators are common.
American alligators are considered an apex predator throughout their range. They are opportunists and their diet is determined largely by both their size and age and the size and availability of prey. Most American alligators eat a wide variety of animals, including invertebrates, fish, birds, turtles, snakes, amphibians, and mammals. Hatchlings mostly feed on invertebrates such as insects, insect larvae, snails, spiders, and worms. As they grow, American alligators gradually expand to larger prey. Once an American alligator reaches full size and power in adulthood, any animal living in the water or coming to the water to drink is potential prey. Most animals captured by American alligators are considerably smaller than itself. Stomach contents show, among native mammals, muskrats and raccoons are some of the most commonly eaten species. In Louisiana, where introduced coypu are common, they are perhaps the most regular prey for adult American alligators, although only larger adults commonly eat this species.
Other animals may occasionally be eaten, even large deer or feral wild boars, but these are not normally part of the diet. American alligators occasionally prey on large mammals, such as deer, but usually do so when fish and smaller prey levels go down. Rarely, American alligators have been observed killing and eating bobcats, but such events are not common and have little effect on bobcat populations. Although American alligators have been listed as predators of West Indian manatees, very little evidence exists of such predation. In the 2000s, when invasive Burmese pythons first occupied the Everglades, alligators have been recorded preying on them, possibly controlling populations, thus preventing the invasive species from spreading northwards.
Occasionally, domestic animals, including dogs, cats, and calves, are taken as available, but are secondary to wild and feral prey. Other prey, including snakes, lizards, and various invertebrates, are eaten occasionally by adults. Water birds, such as herons and egrets, storks, waterfowl and large dabbling rails such as gallinules or coots, are taken when possible. Occasionally, unwary adult birds are grabbed and eaten by American alligators, but most predation on bird species occurs with unsteady fledgling birds in late summer, as fledgling birds attempt to make their first flights near the water's edge.
In 2013, American alligators and other crocodilians were reported to also eat fruit. Such behavior has been witnessed, as well as documented from stomach contents, with the American alligators eating such fruit as wild grapes, elderberries, and citrus fruits directly from the trees. The discovery of this unexpected part of the American alligator diet further reveals that they may be responsible for spreading seeds from the fruit they consume across their habitat. Additionally, American alligators engage in what seems to be cooperative hunting.
In Florida and East TexasEdit
The diet of adult American alligators from central Florida lakes was dominated by fish, highly opportunistically based upon local availability. In Lake Griffin, fish made up 54% of the diet by weight, with catfish being most commonly consumed, while in Lake Apopka, fish made up 90% of the food and mostly shad were taken; in Lake Woodruff, the diet was 84% fish and largely consists of bass and sunfish. Unusually in these regions, reptiles and amphibians were the most important nonpiscivore prey, mostly turtles and water snakes. In southern Louisiana, crustaceans (largely crawfish and crabs) were found to be present in the southeastern American alligators, but largely absent in southwestern American alligators, which consumed a relatively high proportion of reptiles, although fish were the most recorded prey for adults, and adult males consumed a large portion of mammals.
Crocodilians are the most vocal of all reptiles and have a variety of different calls depending on the age, size, and gender of the animal. The American alligator can perform specific vocalizations to declare territory, signal distress, threaten competitors, and locate suitable mates. Juveniles can perform a high-pitched hatchling call (a "yelping" trait common to many crocodilian species' hatchling young) to alert their mothers when they are ready to emerge from the nest. Juveniles also make a distress call to alert their mothers if they are being threatened. Adult American alligators can growl, hiss, or cough to threaten others and declare territory.
Both males and females bellow loudly by sucking air into their lungs and blowing it out in intermittent, deep-toned roars to attract mates and declare territory. Males are known to use infrasound during mating bellows. Bellowing is performed in a "head oblique, tail arched" posture. Infrasonic waves from a bellowing male can cause the surface of the water directly over and to either side of its back to literally "sprinkle", in what is commonly called the "water dance". Large bellowing "choruses" of American alligators during the breeding season are commonly initiated by females and perpetuated by males. Observers of large bellowing choruses have noted they are often felt more than they are heard due to the intense infrasound emitted by males. American alligators bellow in B flat (specifically "B♭1", defined as an audio frequency of 58.27 Hz), and bellowing choruses can be induced by tuba players, sonic booms, and large aircraft.
The breeding season begins in the spring. On spring nights, American alligators gather in large numbers for group courtship, in the aforementioned "water dances". The female builds a nest of vegetation, sticks, leaves, and mud in a sheltered spot in or near the water.
After the female lays her 20 to 50 white eggs, about the size of a goose egg, she covers them with more vegetation, which heats as it decays, helping to keep the eggs warm. This differs from Nile crocodiles, which lay their eggs in pits. The temperature at which American alligator eggs develop determines their sex (see temperature-dependent sex determination). Those eggs hatched at a temperature of 93 °F (34 °C) or more become males, while those at a temperature of 86 °F (30 °C ) or lower become female. The nests built on levees are warmer, thus produce males, while the cooler nests of wet marsh produce females. The female remains near the nest throughout the 65-day incubation period, protecting it from intruders. When the young begin to hatch — their "yelping" calls can sometimes even be heard just before hatching commences — the mother quickly digs them out and carries them to the water in her mouth, as some other crocodilian species are known to do.
The young are tiny replicas of adults, with a series of yellow bands around their bodies that serve as camouflage. Hatchlings gather into pods and are guarded by their mother and keep in contact with her through their "yelping" vocalizations. Young American alligators eat small fish, frogs, crayfish, and insects. They are preyed on by large fish, birds, raccoons, and adult American alligators. Mother American alligators eventually become more aggressive towards their young, which encourages them to disperse. Young alligators grow 3–8 in (7.6–20.3 cm) a year and reach adulthood at 6 ft (1.8 m).
Interactions with exotic speciesEdit
Nutria were introduced into coastal marshes from South America in the mid-20th century, and their population has since exploded into the millions. They cause serious damage to coastal marshes and may dig burrows in levees. Hence, Louisiana has had a bounty to try to reduce nutria numbers. Large American alligators feed heavily on nutria, so American alligators may not only control nutria populations in Louisiana, but also prevent them spreading east into the Everglades. Since hunting and trapping preferentially take the large American alligators that are the most important in eating nutria, some changes in harvesting may be needed to capitalize on their ability to control nutria.
Recently, a population of Burmese pythons became established in Everglades National Park. Substantial American alligator populations in the Everglades may be a contributing factor in keeping the python populations low, preventing the spread of the species north. While events of predation by Burmese pythons on young American alligators have been observed, no evidence of a net negative effect has been seen on overall American alligator populations.
American alligator predation on Florida panthers is rare, but has been documented. Such incidents usually involve a panther trying to cross a waterway or coming down to a swamp or river to get a drink. The American alligator is the only known natural predator of the panther. American alligator predation on American black bears has also been recorded.
Indicators of environmental restorationEdit
American alligators play an important role in the restoration of the Everglades as biological indicators of restoration success. American alligators are highly sensitive to changes in the hydrology, salinity, and productivity of their ecosystems; all are factors that are expected to change with Everglades restoration. American alligators also may control the long-term vegetation dynamics in wetlands by reducing the population of small mammals, particularly coypu, which may otherwise overgraze marsh vegetation. In this way, the vital ecological service they provide may be important in reducing rates of coastal wetland losses in Louisiana. They may provide a protection service for water birds nesting on islands in freshwater wetlands. American alligators prevent predatory mammals from reaching island-based rookeries and in return eat spilled food and birds that fall from their nests. Wading birds appear to be attracted to areas with American alligators and have been known to nest at heavily trafficked tourist attractions with large numbers of American alligators, such as the St. Augustine Alligator Farm in St. Augustine, Florida.
Historically, hunting and habitat loss have severely affected American alligator populations throughout their range, and whether the species would survive was in doubt. In 1967, the American alligator was listed as an endangered species (under a law that was the precursor Endangered Species Act of 1973), since it was believed to be in danger of extinction throughout all or a significant portion of its range.
Both the United States Fish and Wildlife Service (USFWS) and state wildlife agencies in the South contributed to the American alligator's recovery. Protection under the Endangered Species Act allowed the species to recuperate in many areas where it had been depleted. States began monitoring their American alligator populations to ensure that they would continue to grow. In 1987, the USFWS removed the animal from the endangered species list, as it was considered to be fully recovered. The USFWS still regulates the legal trade in American alligators and their products to protect still endangered crocodilians that may be passed off as American alligators during trafficking.
Relationship with humansEdit
Attacks on humansEdit
American alligators are capable of killing humans, but fatal attacks are fairly rare. Mistaken identity leading to an attack is always possible, especially in or near cloudy waters. American alligators are often less aggressive towards humans than larger crocodile species, a few of which (mainly the Nile and saltwater crocodiles) may prey on humans with some regularity. American alligator bites are serious injuries due to the reptile's sheer bite force and risk of infection. Even with medical treatment, an American alligator bite may still result in a fatal infection.
As human populations increase, and as they build houses in low-lying areas or fish or hunt near water, incidents are inevitable where American alligators intrude, or at least appear to intrude, on human life. Since 1948, 257 documented attacks on humans in Florida (about five incidents per year) have been reported, of which an estimated 23 resulted in death. Only nine fatal attacks occurred in the United States throughout the 1970s–1990s, but American alligators killed 12 people between 2001 and 2007. In May 2006, American alligators killed three Floridians in less than a week. At least 28 fatal attacks by American alligators have occurred in the United States since 1970.
Since the late 1880s, alligator wrestling has been a source of entertainment for some. Created by the Miccosukee and Seminole tribes prior to the arrival of Europeans, this tourism tradition continues to persist despite criticism from animal-rights activists.
Today, alligator farming is a large, growing industry in Georgia, Florida, Texas, and Louisiana. These states produce a combined annual total of some 45,000 alligator hides. Alligator hides bring good prices and hides in the 6- to 7-ft range have sold for $300 each. The market for alligator meat is growing, and about 300,000 pounds (140,000 kg) of meat are produced annually. According to the Florida Department of Agriculture and Consumer Services, raw alligator meat contains roughly 200 Calories (840 kJ) per 3-oz (85-g) portion, of which 27 Calories (130 kJ) come from fat.
"Gators" has been the nickname of the University of Florida's sports teams since 1911. In that year, a printer made a spur-of-the-moment decision to print an alligator emblem on a shipment of the school's football pennants. The mascot stuck, perhaps because the team captain's nickname was Gator. Allegheny College and San Francisco State University both have Gators as their mascots, as well.
The Gator Bowl is a college football game held in Jacksonville annually since 1946, with Gator Bowl Stadium hosting the event until the 1993 edition. The Gatornationals is a NHRA drag race held at the Gainesville Raceway in Gainesville since 1970.
- Crocodile Specialist Group (2018). "Alligator mississippiensis ". The IUCN Red List of Threatened Species. 1996: e.T46583A11061981. doi:10.2305/IUCN.UK.1996.RLTS.T46583A11061981.en. Retrieved November 10, 2017.
- Species Alligator mississippiensis at The Reptile Database . www.reptile-database.com.
- American Alligators, American Alligator Pictures, American Alligator Facts – National Geographic. Animals.nationalgeographic.com.
- American alligator Archived April 11, 2013, at the Wayback Machine. Philadelphia Zoo.
- "American Alligator". www.animalspot.net. Retrieved April 24, 2017.
- "Gator factsheet" (PDF). Savannah River Ecology Laboratory. Retrieved August 14, 2012.
- "American Alligator Fact Sheet". The National Zoo. Retrieved December 30, 2013.
- Vilet, Kent (1989). "Social Displays of the American Alligator (Alligator mississippiensis)". American Zoology. 2 (3): 1019–1031. doi:10.1093/icb/29.3.1019.
- Pajerski, Lauren; Schechter, Benjamin; Street, Robin (2000). "Alligator mississippiensis". University of Michigan Museum of Zoology.
- Alligator Cuvier, 1807. ITIS.gov
- Brochu, Christopher A. (2003). "Phylogenetic approaches toward crocodylian history" (PDF). Annual Review of Earth and Planetary Sciences. 31: 357–97. doi:10.1146/annurev.earth.31.100901.141308.[permanent dead link]
- Brochu, Christopher A. (1999). "Phylogenetics, Taxonomy, and Historical Biogeography of Alligatoroidea". Society of Vertebrate Paleontology Memoir. 6: 9–100. doi:10.2307/3889340. JSTOR 3889340.
- Whiting, Evan T.; Steadman, David W.; Vliet, Kent A. (June 1, 2016). "Cranial Polymorphism and Systematics of Miocene and Living Alligator in North America". Journal of Herpetology. 50 (2): 306–315. doi:10.1670/15-023. ISSN 0022-1511.
- Janke, A.; Arnason, U. (1997). "The complete mitochondrial genome of Alligator mississippiensis and the separation between recent archosauria (birds and crocodiles)". Molecular Biology and Evolution. 14 (12): 1266–72. doi:10.1093/oxfordjournals.molbev.a025736. PMID 9402737.
- Green RE, Braun EL, Armstrong J, Earl D, Nguyen N, Hickey G, Vandewege MW, St John JA, Capella-Gutiérrez S, Castoe TA, Kern C, Fujita MK, Opazo JC, Jurka J, Kojima KK, Caballero J, Hubley RM, Smit AF, Platt RN, Lavoie CA, Ramakodi MP, Finger JW, Suh A, Isberg SR, Miles L, Chong AY, Jaratlerdsiri W, Gongora J, Moran C, Iriarte A, McCormack J, Burgess SC, Edwards SV, Lyons E, Williams C, Breen M, Howard JT, Gresham CR, Peterson DG, Schmitz J, Pollock DD, Haussler D, Triplett EW, Zhang G, Irie N, Jarvis ED, Brochu CA, Schmidt CJ, McCarthy FM, Faircloth BC, Hoffmann FG, Glenn TC, Gabaldón T, Paten B, Ray DA (2014). "Three crocodilian genomes reveal ancestral patterns of evolution among archosaurs". Science. 346 (6215): 1254449. doi:10.1126/science.1254449. PMC 4386873. PMID 25504731.
- Thorbjarnarson, J. B. (2010). Black caiman Melanosuchus niger. Crocodiles. Status Survey and Conservation Action Plan, 29–39.
- Woodward, A. R.; White, J. H. & Linda, S. B. (1995). "Maximum size of the alligator (Alligator mississippiensis)". Journal of Herpetology. 29 (4): 507–513. doi:10.2307/1564733. JSTOR 1564733.
- Clippinger, T. L.; Avery Bennett, R.; Johnson, C. M.; Vliet, K. A.; Deem, S. L.; Orós, J.; Brown, M. B. (2000). "Morbidity and mortality associated with a new mycoplasma species from captive American alligators (Alligator mississippiensis)". Journal of Zoo and Wildlife Medicine. 31 (3): 303–314. doi:10.1638/1042-7260(2000)031[0303:mamawa]2.0.co;2. PMID 11237136.
- Charles, S.; Ross, A. and Garnett, Stephen (1989) Crocodiles and Alligators. Checkmark Books. ISBN 978-0-8160-2174-1.
- Wood, Gerald (1983). The Guinness Book of Animal Facts and Feats. ISBN 978-0-85112-235-9.
- "Crocodilian Species—American Alligator (Alligator mississippiensis)". Flmnh.ufl.edu. Retrieved October 14, 2008.
- Smith, E. N.; Standora, E. A. & Robertson, S. L. (1984). "Physiological thermoregulation of mature alligators". Comparative Biochemistry and Physiology. A, Comparative Physiology. 77 (1): 189–93. doi:10.1016/0300-9629(84)90033-1. PMID 6141029.
- "Record gator caught in Southwest Arkansas". FoxNews.com. Retrieved March 15, 2014.
- Everglades National Park Flora & Fauna Page. Everglades National Park
- Florida alligator. Floridaadventuring.com (March 2, 2016). Retrieved on 2016-09-07.
- Goodwin, Thomas M. (1979). "Seasonal activity ranges and habitat preferences of adult alligators in a north-central Florida lake". Journal of Hepatology. 13 (2): 157–64. doi:10.2307/1563922. JSTOR 1563922.
- Honeyfield, D. C.; Ross, J. P.; Carbonneau, D. A.; Terrell, S. P.; Woodward, A. R.; Schoeb, T. R.; Hinterkopf, J. P. (2008). "Pathology, physiologic parameters, tissue contaminants, and tissue thiamine in morbid and healthy central Florida adult American alligators (Alligator mississippiensis)". Journal of Wildlife Diseases. 44 (2): 280–294. doi:10.7589/0090-3558-44.2.280. PMID 18436661.
- Ruben, J. A.; Jones, T. D. (2000). "Selective factors associated with the origin of fur and feathers". American Zoologist. 40 (4): 585–596. doi:10.1668/0003-1569(2000)040[0585:sfawto]2.0.co;2.
- Saalfeld, D. T.; Webb, K. K.; Conway, W. C.; Calkins, G. E.; Duguay, J. P. (2008). "Growth and condition of American alligators (Alligator mississippiensis) in an inland wetland of east Texas". Southeastern Naturalist. 7 (3): 541–550. doi:10.1656/1528-7092-7.3.541.
- Webb, GJW.; Messel, H. (1978). "Morphometric analysis of Crocodylus porosus from the north coast of Arnhem Land, northern Australia". Australian Journal of Zoology. 26 (1): 1–27. doi:10.1071/zo9780001.
- Lance, V. A.; Elsey, R. M.; Lang, J. W. (2000). "Sex ratios of American alligators (Crocodylidae): male or female biased?". Journal of Zoology. 252 (1): 71–78. doi:10.1017/s0952836900009080.
- "American Alligator: Species Profile". US National Park Service. Retrieved August 14, 2012.
- "Zoo keeps albino alligator in the dark". NBC News.com. May 11, 2007. Retrieved August 15, 2012.
- Erickson, Gregory M.; Lappin, A. Kristopher; Vliet, Kent A. (March 2003). "The ontogeny of bite-force performance in American alligator (Alligator mississippiensis)". Journal of Zoology. 260 (3): 317–327. doi:10.1017/s0952836903003819. ISSN 0952-8369.
- Erickson, Gregory M.; Lappin, A. Kristopher; Parker, Trevor; Vliet, Kent A. (2004). "Comparison of bite-force performance between long-term captive and wild American alligators (Alligator mississippiensis)" (PDF). Journal of Zoology. 262 (1): 21–28. doi:10.1017/S0952836903004400.
- Erickson, GM; Gignac PM; Steppan SJ; Lappin AK; Vliet KA; et al. (2012). "Insights into the Ecology and Evolutionary Success of Crocodilians Revealed through Bite-Force and Tooth-Pressure Experimentation". PLoS ONE. 7 (3): e31781. doi:10.1371/journal.pone.0031781. PMC 3303775. PMID 22431965.
- Reilly, S. M.; Elias, J. A. (1998). "Locomotion in alligator mississippiensis: kinematic effects of speed and posture and their relevance to the sprawling-to-erect paradigm" (PDF). The Journal of Experimental Biology. 201 (18): 2559–74. PMID 9716509.
- Fish, F. E. (1984). "Kinematics of undulatory swimming in the American alligator" (PDF). Copeia. 1984 (4): 839–43. doi:10.2307/1445326. JSTOR 1445326. Archived from the original (PDF) on October 21, 2013.
- Farmer, C. G.; Sanders, K. (2010). "Unidirectional airflow in the lungs of American alligators". Science. 327 (5963): 338–340. doi:10.1126/science.1180219. PMID 20075253.
- Uriona, T. J.; Farmer, C. G. (2008). "Recruitment of the diaphragmaticus, ischiopubis and other respiratory muscles to control pitch and roll in the American alligator (Alligator mississippiensis)". Journal of Experimental Biology. 211 (7): 1141–11477. doi:10.1242/jeb.015339. PMID 18344489.
- "SEARCHING FOR THE NORTHERN AND SOUTHERN DISTRIBUTION LIMITS OF TWO CROCODILIAN SPECIES: Alligator mississippiensis AND Crocodylus moreletii IN SOUTH TEXAS, US, AND IN NORTHERN TAMAULIPAS, MEXICO". Retrieved August 16, 2018.
- Tennessee Wildlife Resources Agency - Alligators. , accessed March 28, 2018
- "NAS - Nonindigenous Aquatic Species: Alligator mississippiensis". USGS.
- "Elusive Chattahoochee alligator caught in Cobb County". myajc. Retrieved December 17, 2016.
- "American Alligator (Alligator mississippiensis)". Savannah River Ecology Lab. Retrieved August 16, 2012.
- "What's the difference between a crocodile and an alligator?". Flmnh.ufl.edu. Retrieved August 26, 2012.
- Guggisberg, C.A.W. (1972). Crocodiles: Their Natural History, Folklore, and Conservation. Newton Abbot: David & Charles. p. 195. ISBN 978-0-7153-5272-4.
- Lance, Valentine A. (2003). "Alligator physiology and life history: the importance of temperature". Experimental Gerontology. 38 (7): 801–805. doi:10.1016/S0531-5565(03)00112-8. PMID 12855291.
- Dinets, Vladimir; Britton, Adam; Shirley, Matthew (2013). "Climbing behaviour in extant crocodilians" (PDF). Herpetology Notes. 7: 3–7. (published online January 25, 2014)
- Rice, Ken G.; Mazzotti, Frank (October 2005). "American Alligator Ecology and Monitoring for the Comprehensive Everglades Restoration Plan" (PDF). University of Florida IFAS Extension.
- Campell, Mark R.; Mazzotti, Frank J. (2004). "Characterization of Natural and Artificial Alligator Holes" (PDF). Southeastern Naturalist. 3 (4): 583–94. doi:10.1656/1528-7092(2004)003[0583:CONAAA]2.0.CO;2.[permanent dead link]
- WEC203/UW230: Living with Alligators: A Florida Reality. Edis.ifas.ufl.edu. Retrieved on August 21, 2012.
- Dinets, V; Brueggen, JC; Brueggen, J.D. (2013). "Crocodilians use tools for hunting". Ethology, Ecology and Evolution. 1: 74–78. doi:10.1080/03949370.2013.858276.
- "Crocodiles are cleverer than previously thought: Some crocodiles use lures to hunt their prey". ScienceDaily. December 4, 2013. Retrieved December 8, 2013.
- Dinets, V. L. (2011). "On terrestrial hunting in crocodilians" (PDF). Herpetological Bulletin. 114: 15–18. Archived from the original (PDF) on October 15, 2011.
- Jason Bittel (September 20, 2017). "Alligators Attack and Eat Sharks, Study Confirms". National Geographic.
- Nifong, James C.; Lowers, Russell H. (2017). "Reciprocal Intraguild Predation between Alligator mississippiensis (American Alligator) and Elasmobranchii in the Southeastern United States". Outheastern Naturalist. 16 (3): 383–396. doi:10.1656/058.016.0306.
- Valentine Jr, J. M.; Walther, J. R.; McCartney, K. M.; Ivy, L. M. (1972). "Alligator diets on the Sabine National Wildlife Refuge, Louisiana". The Journal of Wildlife Management. 36 (3): 809–815. doi:10.2307/3799434. JSTOR 3799434.
- Keddy, P.A., L. Gough, J.A. Nyman, T. McFalls, J. Carter and J. Siegrist (2009). Alligator hunters, pelt traders, and runaway consumption of Gulf coast marshes: A trophic cascade perspective on coastal wetland losses. pp. 115–133 in B.R. Silliman, E.D. Grosholz, and M.D. Bertness (eds.) Human Impacts on Salt Marshes. A Global Perspective. University of California Press, Berkeley, CA ISBN 0-520-25892-4 Google Books
- "American Alligator". News Daily. Archived from the original on March 18, 2015. Retrieved February 28, 2018.
- "Gator eats bobcat". Flickr. November 7, 2012. Retrieved November 7, 2012.
- "Sneaky alligator nearly eats bobcat". Kens5. Archived from the original on January 11, 2014. Retrieved June 1, 2012.
- Whitaker, John O. (1996). The Audubon Society Field Guide to North American Mammals. New York, pg. 808. ISBN 978-0-679-44631-6.
- Dorcas, M. E.; Willson, J. D.; Reed, R. N.; Snow, R. W.; Rochford, M. R.; Miller, M. A.; Hart, K. M. (2012). "Severe mammal declines coincide with proliferation of invasive Burmese pythons in Everglades National Park". Proceedings of the National Academy of Sciences. 109 (7): 2418–2422. doi:10.1073/pnas.1115226109. PMC 3289325. PMID 22308381.
- Nolen, R. S. (2012). "How big is Florida's python problem?". J Am Vet Med Assoc. 240 (7): 778–782. doi:10.2460/javma.240.7.778. PMID 22443430.
- Choi, Charles Q. (August 30, 2013). "Crocodiles and alligators like to chomp down on ... fruit !". NBC News: Science. Retrieved August 31, 2013.
- Platt, S.G; Elsey, R.M; Liu, H. (2013). "Frugivory and seed dispersal by crocodilians: an overlooked form of saurochory?". Journal of Zoology. 291 (2): 87. doi:10.1111/jzo.12052.
- F. Wayne King, John Thorbjarnarson and Carlos Yamashita. 1998. Cooperative Feeding, A Misinterpreted and Under-Reported Behavior of Crocodilians. 9 p. Available at: http://www.flmnh.ufl.edu/herpetology/links/cooperative-feeding (Online: 1 August 1998)
- Dinets, Vladmir (2014). "Apparent coordination and collaboration in cooperatively hunting crocodilians". Ethology Ecology & Evolution. 27 (2): 244–250. doi:10.1080/03949370.2014.915432.
- Rice, A. N. (2004). Diet and condition of American alligators (Alligator mississippiensis) in three central Florida lakes (Doctoral dissertation, University of Florida).
- Gabrey, S. W. (2010). "Demographic and geographic variation in food habits of American alligators (Alligator mississippiensis) in Louisiana" (PDF). Herpetological Conservation and Biology. 5 (2): 241–250.
- Saalfeld, D. T.; Conway, W. C.; Calkins, G. E. (2011). "Food Habits of American Alligators (Alligator mississippiensis) in East Texas". Southeastern Naturalist. 10 (4): 659–672. doi:10.1656/058.010.0406.
- Riede, T; Tokuda, I. T.; Farmer, C. G. (2011). "Subglottal pressure and fundamental frequency control in contact calls of juvenile Alligator mississippiensis". Journal of Experimental Biology. 214 (Pt 18): 3082–95. doi:10.1242/jeb.051110. PMC 3160820. PMID 21865521.
- Britton, Adam. "Crocodile Talk". University of Bristol and Florida Museum of Natural History.
- "Yelping" of alligator hatchlings. YouTube.com (September 3, 2013). Retrieved on 2016-09-07.
- Male alligator "sprinkling" while bellowing in near-infrasound during courtship. YouTube.com (April 28, 2010). Retrieved on 2016-09-07.
- Garrick, L. D.; Lang, J. W. (1977). "Social Displays of the American Alligator". American Zoologist. 17: 225–239. doi:10.1093/icb/17.1.225.
- Garrick, L.; Lang, J.; Herzog, H. (1978). "Social Signals of Adult American Alligators". 60 (3): 153–192. Cite journal requires
- Kilnkenberg, Jeff (June 21, 2013). "Alligators in B Flat? Gatorland's denizens roar in ecstasy". Tampa Bay Times.
"We want to hit the B flat two octaves below middle C, " Mickelsen reminded his young assistant. "At 57 hertz. That's what that old scientific report advised...BLAAAA!...Though only a few clouds scudded across the sky, we heard what sounded like thunder in the distance. It was a randy male American alligator, turned on by tuba, telling the world that he was a stud...He lifted his upper body out of the water while lowering the middle and raising his tail. Though he barely moved, a droplet spray exploded from the water covering his back. "The water dance!" Tim Williams cried. Toxic let loose a roar that shook the earth.
- Dinets, V. L. (2010). "Nocturnal behavior of the American Alligator (Alligator mississippiensis) in the wild during the mating season". Herpetological Bulletin. 111: 4–11.
- Joanen, T.; Ferguson, M. W. J. (1982). "Temperature of egg incubation determines sex in Alligator mississippiensis". Nature. 296 (5860): 850–53. doi:10.1038/296850a0. PMID 7070524.
- Hunt, R. H.; Watanabe, M. E. (1982). "Observations on the maternal behavior of the American alligator, Alligator mississippiensis". Journal of Herpetology. 16 (3): 235–39. doi:10.2307/1563716. JSTOR 1563716.
- Gator-guzzling python comes to messy end. Associated Press (October 5, 2005). Retrieved 2008-03-11.
- Butler, Rhett A. (October 5, 2005) Python explodes after swallowing 6-foot alligator in Florida Everglades. Mongabay.com. Retrieved 2008-03-11.
- United States Department of the Interior, U.S. Geological Survey (February 20, 2008). USGS Maps Show Potential Non-Native Python Habitat Along Three U.S. Coasts. www.usgs.gov. Retrieved 2008-03-11.
- Sivlerstein, Alvin (1997). The Florida Panther. Brooksville, Connecticut: Millbrook Press. pp. 41+. ISBN 0-7613-0049-X.
- "American Alligator". Animal List.
- "Alligators". Aquatic Community.
- "Key West Florida Attractions | Alligator Exhibit". Key West Aquarium. Retrieved December 20, 2012.
- Harvey, Rebecca G.; Brandt, Laura A.; Mazzotti, Frank J. (October 2011). "The American Alligator: An Indicator Species for Everglades Restoration" (PDF). University of Florida IFAS Extension.
- Keddy, P.A. (2010). Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. ISBN 0-521-78367-4.
- White, C.; Frederick, P.; Main, M.; Rodgers, J. (May 2005). "Nesting Island Creation for Wading Birds" (PDF). University of Florida IFAS Extension.
- "American Alligator Alligator mississippiensis" (PDF). U.S. Fish and Wildlife Service. February 2008. Retrieved September 3, 2012.
- Crocodile and Alligator Differences – Animal Facts for Kids. Sciencekids.co.nz (July 11, 2012). Retrieved on 2012-08-21.
- Harding, Brett E.; Wolf, Barbara C. (2006). "Alligator Attacks in Southwest Florida". Journal of Forensic Sciences. 51 (3): 674–677. doi:10.1111/j.1556-4029.2006.00135.x. PMID 16696720.
- McLaughlin, Eliott C.; Almasy, Steve and Shoichet, Catherine E. (2016-06-16) Disney alligator attack: Resort to add warning signs, source says. CNN
- "A String of Deaths by Gators in Florida". nytimes.com. May 15, 2006. Retrieved May 15, 2006.
- "Alligator wrestling – cruelty or tradition?". BBC News.com. March 17, 2009. Retrieved August 29, 2012.
- Lane, Thomas J.; Ruppert, Kathleen C. (June 2008). "Alternative Opportunities for Small Farms:Alligator Production Review" (PDF). University of Florida. Retrieved August 29, 2012.
- Reig Eimeric (2006). "Gator Maters: Florida farmers find lucrative business mating alligators". Orange and Blue Magazine. Archived from the original on May 30, 2013. Retrieved August 29, 2012.
- "Alligator". Florida State Symbols. Florida Division of Historical Resources. 2013. Retrieved April 6, 2013.
- "About Louisiana". Louisiana.gov. State of Louisiana. Archived from the original on March 24, 2013. Retrieved April 6, 2013.
- Act No. 302 of July 1, 2005 (PDF). Retrieved April 6, 2013.
- "History: 1906–1927, early Gainesville". University of Florida. Archived from the original on December 31, 2010. Retrieved February 13, 2011.
- "Why Gators?". Allegheny College. Retrieved March 30, 2019.
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- Boulenger GA (1889). Catalogue of the Chelonians, Rhynchocephalians, and Crocodiles in the British Museum (Natural History). New Edition. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). x + 311 pp. + Plates I-VI. (Alligator mississippiensis, p. 290).
- Daudin FM (1802). Histoire Naturelle, Générale et Particulière des Reptiles; Ouvrage faisant suite à l'Histoire Naturelle générale et particulière, composée par Leclerc de Buffon; et rédigée par C.S. Sonnini, membre de plusieurs sociétés savantes. Tome Second [Volume 2]. 432 pp. Paris: F. Dufart. ("Crocodilus mississipiensis [sic]", new species, pp. 412–416). (in French and Latin).
- Powell R, Conant R, Collins JT (2016). Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, Fourth Edition. Boston and New York: Houghton Mifflin Harcourt. xiv + 494 pp., 47 Plates, 207 Figures. ISBN 978-0-544-12997-9. (Alligator mississippiensis, p. 170 + Plate 13 + photographs on pp. 166–167, 465).
- Smith, Hobart M.; Brodie, Edmund D., Jr. (1982). Reptiles of North America: A Guide to Field Identification. New York: Golden Press. 240 pp. ISBN 0-307-13666-3. (Alligator mississippiensis, pp. 208–209).