LOUISIANA WETLANDS

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Louisiana Wetland Animals/ Reptiles: American Alligator

REPTILES: American Alligator

American Alligator

Alligator mississippiensis

Presently found: Louisiana, Missisissppi, Arkansas, eastern Texas, Florida, North Carolina.

History: Have been around about 200 million years and survived the dinosaurs. More than 500 years ago, the first explorers to America encountered “serpents” that would dive into a lake or river when approached. In Late 1700s, naturalist William Bartram explored the St. John River and saw the alligators.

Habitat: Amphibious. Fresh water, swamps, marshes, rivers and lakes. Some brackish water. Hibernate in dens. Optimum preferred temp. is 89 degrees.

Size: 7-9” at birth. 9-18’ and 160-550 lbs as adult. Rarely seen in wild bigger than 10’ due to hunting. Grow 1’ a year for the first 5-6 years, then grow very slowly. (Can approximate age during these first years by measuring number of inches from nostril to eyes: 1 inch=1 year.)

Life span: 50-60 years

Description: Broader snout than crocodile. Adults are dull grey and dark olive. Young are black and yellow.

Diet: Can be scavengers. Indiscriminate feeder: small deer, hog, beetle, fish, nutria, small mammals and birds depending on season and size of alligator. Needs warmth to digest food, so will not eat in winter months. Strong stomach acid can dissolve bones and fur. ZOO DIET: nutria, chicken, rats, mice, fish, crickets, beef hearts, twice a week. Zoo alligators will not be fed from Nov thru March.

Reproduction: Mating in Spring in the water. Find each other through use of scent glands. Male has deep, booming roar. Female answers with bellow. Male will mate w/several females.

· Female builds next about 1 mo. After mating. Chooses dry spot on land, usually under a tree to protect from direct sun. Also builds close to water and packs with decaying plant material. Finished nest is 3ft. high and 7ft. wide.

· Lays 30-70 eggs in a hole in middle of mound and covers. As plants decay, it incubates eggs. Nest temp. 85-92 degrees, hatchlings are mostly males. Less than 85, females.

· Female will guard from raccoons, opossums and wild pigs. Hisses to scare them.

· Two months later, babies break egg with egg tooth, which falls off later. Babies grunts are heard by mother who then removes nest material so babies can get out. Will carry them in her mouth to the water.

Senses

SIGHT: Have nictitating membrane for underwater use. Nocturnal eye structure. “Crocodile tears” are tears full of air bubbles secreted to protect its sensitive eyes. Have no peripheral vision but are angled forward and on top of head for better depth perception.

HEARING: Internal ears covered by flaps of skin. Sound is the most efficient means of communication in the dense swamp. Males can be heard up to a mile away. Also send subsonic vibrations with their throat and stomach through the water.

SMELL: Moderate. Can close nostrils when diving. Have musk glands on cloaca and both sides of the lower jaw – active when mating.

Mouth:        Broader snout more adapted for catching prey at waters edge. Muscles are geared for clamping down, roughly 2000psi. Once closed, mouth can be closed with little pressure.

·        Have about 60 teeth, which they will lose and replace. Throughout their lifetime, will go through about 1000 teeth. Alligators have only upper teeth visible when mouth is shut. (Crocodiles show upper and lower teeth.)

·        Throat has closeable flap so they can open mouth under water.

Heart:          4-chambered, just like human heart. Can slow their HR to 1-2 beats/min for diving and hibernation. Can perform their own heart “bypass” by shunting blood away from lungs while they are under water. Have been documented to remain under water 5-6 hours.

Feet:            Webbed for slow swimming and walking on top of mud and slow swimming. Can run 20-30 mph (humans run 12-15 mph).

Tail:              For fast swimming (legs tucked against body), defense and fat storage.

Scales:       Scales on the back have bony “osteoderms” which house series of blood vessels. These osteoderms act as solar panels: sun warms the blood in them, then blood circulates. Allows body temp. regulation while floating in the water w/just their eyes, nose and “solar panels” above the surface.

Hunting      Forte is floating or lying motionless and camouflaged until prey wanders within range. Overcome prey by grabbing and crushing. Can run 20-30 mph. (Humans run 12 –15 mph)

Status:       Was placed on Endangered list in 1967 due to over-hunting and habitat destruction. Have recovered but still classified as T/SA, Threatened by Similarity of Appearance. In La. and Fla. “nuisance alligator” control programs are in effect. In Texas, is usually caught and transported to less populated area. Limited hunting in Tex. and La.

Other fun Info:

Can swim faster than a man paddling a canoe
Can climb just as well as a lizard – a 6” chain link fence is no obstacle.
Most alligator attacks occur only when they feel threatened or when they are surprised, like when about to be stepped on in murky water.
The only other species of alligator is found in China, the Chinese Alligator, which grows to 6-7 feet.
Winter dens are under water and dug out from riverbank, with wider space at one end for air space. Will spend cold days there but come out to sun itself on warmer days.
Is called a “key species” because it affects the envt. Where it lives to a greater extent than most.
American alligators are members of the crocodilian family, which has been around since the dinosaur age.
Out of the 22 species of modern crocodiles alive today, 17 are on the verge of extinction.
Between 1870 and 1970, over 10 million alligators were killed for their skin (an excellent reason to opt for synthetics in the shoe and purse departments).

WHITE ALLIGATOR: Sometimes, alligators display a genetic mutation involving two recessive genes which causes the offspring to be white with blue eyes, or “Leucistic.” (They are not albino!)

Probability of this happening is 1 in 10,000. It is uncommon for these to survive long in wild because their white color makes them easy prey for birds, snakes and other alligators.

In 1987, 19 white male hatchlings were found by a Cajun fisherman on Lands owned by the Louisiana Land and Exploration Company (LL&E) who donated four of them to Audubon Institute. Today AOA has one, Zoo has one, some have died, some are on loan to other zoos and several live on an LL&E alligator farm.
Although leucism exists in other animal species, no leucistic alligators were known until this discovery. A second sighting was made in 1994, when Audubon encountered a wild-born, leucistic female gator 100 miles from the site of the 19 hatchlings.

Habits and Habitats

· Occurs in many bodies of still or slow-moving water – lakes, bayous, swamps, canals, and even occasionally ditches.

· They will enter the salt marsh on occasion but will not nest there.

· In a swamp or marsh, alligators will dig holes 4-10 ft. in diameter and 4-6 ft. deep that are connected to the underground dens they construct.

· These dens may be as long as 40 ft. and serve primarily as a retreat for the winter, when the alligator is largely inactive.

· Dens are important to the environment during droughts. They are usually the only source for water.

Mating

· Alligators do not begin breeding until they are at least 10 years old or about 6 feet long.

· During this season the male alligators are extremely territorial and frequently make a low roar or bellowing sound that can travel considerable distances in water! This sound alerts female alligators of their presence.

· Head slapping – The act of rapidly swinging the head down to make contact with the water surface transmits aural and visual messages.

· Also during this time the males emit a powerful sweet-smelling scent from two musk glands on their lower jaws.

Nest building

· The female alligator will pick high ground to build a mound nest of rotting vegetation lined with mud at the beginning of the summer when it is damp and warm.

· Between 20 to 50 eggs are laid in a conical depression in the top of the nest which is then covered over with more vegetation. When the vegetation decomposes it warms up and incubates the eggs.

· Incubation period is usually around 65 days depending on temperature.

· The juveniles will form a pod and remain close to the mother for up to three years.

· This pod provides protection in numbers and a swift response from the guardian female if they begin calling (chirping) as a result of impending danger.

· Juveniles will grow rapidly; up to a foot a year for the first five years.

Diet

· Alligators will feed on virtually any animal they can capture depending on the alligator’s size.

· Juveniles will eat insects, small fish, crawfish, crabs, small frogs, and small reptiles.

Did you know?

· The largest wild alligator ever caught was captured in the 1890s in Louisiana and it was 19 ft. 2 in. long.

· We get our juvenile alligators from Rockefellow Refuge as hatchlings. We keep them for a year and then return them. The refuge then releases them.

WHITE ALLIGATOR
Sometimes, alligators display a genetic mutation involving two recessive genes which causes the offspring to be white with blue eyes, or “leucistic.” (They are not albino, though true albinistic American alligators do exist!)

Probability of this happening is 1 in 10,000. It is uncommon for these to survive long in wild because their white color makes them easy prey for birds, snakes and other alligators.

In 1987, 19 white male hatchlings were found by a Cajun fisherman on lands owned by the Louisiana Land and Exploration Company (LL&E) who donated four of them to Audubon Institute. Today AOA has one, Zoo has one, some have died, some are on loan to other zoos and several live on an LL&E alligator farm under the care of Audubon Nature Institute.
Although leucism exists in other animal species, no leucistic alligators were known until this discovery. A second sighting was made in 1994, when Audubon encountered a wild-born, leucistic female gator 100 miles from the site of the 19 hatchlings.