ALLIGATORS

Alligators live in freshwater environments such as ponds, marshes, rivers and swamps. Although alligators have heavy bodies and slow metabolisms, they are capable of short bursts of speed that can exceed 30 miles per hour.

Identification
The American alligator (Alligator mississippiensis) is the most common of two crocodilians native to the United States and is one of 22 crocodilian species worldwide. The other native crocodilian is the American crocodile (Crocodylus acutus). Caimans (Caiman spp.), imported from Central and South America, are occasionally released in the United States and can survive and reproduce in Florida. The American alligator is distinguished from the American crocodile and caiman by its more rounded snout and black and yellow-white coloration. American crocodiles and caimans are olive-brown in color and have more pointed snouts. American alligators and crocodiles are similar in physical size, whereas caimans are 40% smaller.

Range
The American alligator is found in wetlands throughout the coastal plain of the southeastern United States. Viable alligator populations are found in Texas, Oklahoma, Arkansas, Louisiana, Mississippi, Alabama, Florida, Georgia, South Carolina, and North Carolina. The northern range is limited by low winter temperatures. Alligators are rarely found south of the Rio Grande drainage. Alligators prefer fresh water but also inhabit brackish water and occasionally venture into salt water. American crocodiles are scarce and, in the United States, are only found in the warmer coastal waters of Florida, south of Tampa and Miami. Caimans rarely survive winters north of central Florida and reproduce only in southernmost Florida.

Habitat
Alligators can be found in almost any type of fresh water, but population densities are greatest in wetlands with an abundant food supply and adjacent marsh habitat for nesting. In Texas, Louisiana, and South Carolina, the highest densities are found in highly productive coastal impoundments. In Florida, highest densities occur in nutrient-enriched lakes and marshes. Coastal and inland marshes maintain the highest alligator densities in Georgia, Alabama, and Mississippi. Alligators commonly inhabit urban wetlands (canals, lagoons, ponds, impoundments, and streams) throughout their range.

Food Habits
Alligators are exclusively carnivorous and prey upon whatever creatures are most available. Juvenile alligators (less than 4 feet [1.2 m]) eat crustaceans, snails, and small fish; subadults (4 to 6 feet [1.2 to 1.8 m]) eat mostly fish, crustaceans, small mammals, and birds; and adults (greater than 6 feet [1.8 m]) eat fish, mammals, turtles, birds, and other alligators. Diets are range-dependent; in Louisiana coastal marshes, adult alligators feed primarily on nutria (Myocastor coypus), whereas in Florida and northern Louisiana, rough fish and turtles comprise most of the diet. Recent studies in Florida and Louisiana indicate that cannibalism is common among alligators. Alligators readily take domestic dogs and cats. In rural areas, larger alligators take calves, foals, goats, hogs, domestic waterfowl, and occasionally, full-grown cattle and horses.

General Biology, Reproduction, and Behavior
Alligators are ectothermic — they rely on external sources of heat to maintain body temperature. They are most active at warmer temperatures and prefer 82o to 92o F (28o to 33o C). They stop feeding when ambient temperature drops below 70o F (21o C) and become dormant below 55o F (13o C).

Alligators are among the largest animals in North America. Males can attain a size of more than 14 feet (4.3 m) and 1,000 pounds (473 kg). Females can exceed 10 feet (3.1 m) and 250 pounds (116 kg). Alligators of both sexes become sexually mature when they attain a length of 6 to 7 feet (1.8 to 2.1 m), but their full reproductive capacity is not realized until females and males are at least 7 feet (2.1 m) and 8 feet (2.4 m) long, respectively.

Alligators begin courtship in April throughout most of their range and breed in late May and early June. Females lay a single clutch of 30 to 50 eggs in a mound of vegetation from early June to mid-July. Nests average about 2 feet (0.6 m) in height and 5 feet (1.5 m) in diameter. Nests are constructed of the predominant surrounding vegetation, which is commonly cordgrass (Spartina spp.), sawgrass (Cladium jamaicense), cattail (Typha spp.), giant reed (Phragmytes spp.), other marsh grasses, peat, pine needles, and/or soil. Females tend their nests and sometimes defend them against intruders, including humans. Eggs normally take 65 days to complete incubation. In late August to early September, 9 to 10-inch (23 to 25-cm) hatchlings are liberated from the nest by the female. She may defend her hatchlings against intruders and stay with them for up to 1 year, but gradually loses her affinity for them as the next breeding season approaches.

Growth rates of alligators are variable and dependent on diet, temperature, and sex. Alligators take 7 to 10 years to reach 6 feet (1.8 m) in Louisiana, 9 to 14 years in Florida, and up to 16 years in North Carolina. When maintained on farms under ideal temperature and nutrition, alligators can reach a length of 6 feet (1.8 m) in 3 years.

Alligators are not normally aggressive toward humans, but aberrant behavior occasionally occurs. Alligators can and will attack humans and cause serious injury or death. Most attacks are characterized by a single bite and release with resulting puncture wounds. Single bites are usually made by smaller alligators (less than 8 feet [2.4 m]) and result in an immediate release, possibly because they were unsure of their intended prey. One-third of the attacks, however, involve repeated bites, major injury, and sometimes death. Serious and repeated attacks are normally made by alligators greater than 8 feet in length and are most likely the result of chase and feeding behavior. Unprovoked attacks by alligators smaller than 5 feet (1.5 m) in length are rare.

Contrary to popular belief, few attacks can be attributed to wounded or territorial alligators or females defending their nests or young. Necropsies of alligators that have attacked humans have shown that most are healthy and well-nourished. It is unlikely that alligator attacks are related to territorial defense. When defending a territory, alligators display, vocalize, and normally approach on the surface of the water where they can be more intimidating. In most serious alligator attacks, victims were unaware of the alligator prior to the attack. Female alligators frequently defend their nest and young, but there have been no confirmed reports of humans being bitten by protective females. Brooding females typically try to intimidate intruders by displaying and hissing before attacking.

Alligators quickly become conditioned to humans, especially when food is involved. Feeding-habituated alligators lose their fear of humans and can be dangerous to unsuspecting humans, especially children. Many aggressive or “fearless” alligators have to be removed each year following feeding by humans. Ponds and waterways at golf courses and high-density housing create a similar problem when alligators become accustomed to living near people.

Damage and Damage Identification
Damage by alligators is usually limited to injuries or death to humans or domestic animals. Most alligator bites occur in Florida, which has documented approximately 140 unprovoked attacks from 1972 to 1991, or about 7 per year. Since 1972, 5 deaths have been positively attributed to alligators. Historically, nonfatal attacks have also been documented in South Carolina (8), Louisiana (2), Texas (1), Georgia (1), and Alabama (1).

Alligators inflict damage with their sharp, cone-shaped teeth and powerful jaws. Bites are characterized by puncture wounds and/or torn flesh. Alligators, like other crocodilians that take large prey, prefer to seize an appendage and twist it off by spinning. Many serious injuries have involved badly damaged and broken arms on humans and legs on animals. Sometimes alligators bite or eat previously drowned persons. Coroners can usually determine whether a person drowned before or after being bitten. Stories of alligators breaking the legs of full-grown men with their tails are unfounded.

Alligators sometimes excavate extensive burrows or dens for refuges from cold temperatures, drought, and predators (other alligators and humans). Burrowing by alligators can damage dikes in impoundments.

Economics of Damage and Control
Alligators can cause injuries and death to humans, livestock, and pets. All alligator bites require medical treatment and serious bites may require hospitalization. Infections can result from alligator bites, particularly from the Aeromonas spp. bacteria.

Lawsuits that arise from findings of negligence on the part of a private owner or governmental agency responsible for an attack site can lead to significant economic liability.

In Florida, approximately 15% of the alligator complaints are due to fear of pet losses and, to a lesser extent, livestock losses. Losses of livestock other than domestic waterfowl, however, are uncommon and difficult to verify. Levees damaged by alligator burrows or dens may require repair.

Alligators are valuable for their skin and meat. An average-sized nuisance alligator typically yields 8 feet (2.4 m) of skin and 30 pounds (13.5 kg) of boneless meat with a wholesale value of $390 (at $30 per foot for skins and $5 per pound for meat). Other products such as skulls, teeth, fat, and organs can be sold, but account for less than 10% of the value of an alligator. Nuisance alligator control programs in several states use the sale of alligator skins to offset costs of removal and administration.

Florida has the most pressing nuisance alligator problem and currently harvests about 4,000 alligators per year. Nuisance alligator harvests also occur in Louisiana (600), Georgia (400), South Carolina (250), and Texas (50).

Legal Status
The American alligator is federally classified as “threatened due to similarity of appearance” to other endangered and threatened crocodilians. This provides federal protection for alligators but allows state-approved management and control programs. Alligators can be legally taken only by individuals with proper licenses or permits. Florida, Louisiana, Georgia, South Carolina, and Texas have problem or nuisance alligator control programs that allow permitted hunters to kill or facilitate the removal of nuisance alligators. Other states use state wildlife officials to remove problem animals.


Damage Prevention and Control Methods

Exclusion
Bulkheads along edges of lakes and waterways. Wire mesh fences.

Habitat Modification
Minimize emergent vegetation. Drain ponds and borrow pits where appropriate and permitted.

Frightening
Prodding or other harassment can increase wariness. Hunting pressure increases wariness and avoidance of people.

Repellents
None are registered.

Toxicants
None are registered.

Fumigants
None are registered.

Trapping
Baited hooks and trip-snare traps are most effective.

Shooting
Hunt during the day or night with rifles or crossbows.

Other Methods
Hunt with detachable-head harpoons or handheld, breakaway pole snares. Capture with snatch hooks or tongs.



ACKNOWLEDGEMENTS
The above information was adapted from PREVENTION AND CONTROL OF WILDLIFE DAMAGE with permission of the editors, Scott E. Hygnstrom, Robert M. Timm, and Gary E. Larson (Cooperative Extension Division, Institute of Agriculture and Natural Resources University of Nebraska-Lincoln, United States Department of Agriculture Animal and Plant Health Inspection Service, Animal Damage Control, Great Plains Agricultural Council Wildlife Committee).