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ALLIGATORS

Allan R. Woodward

Alligator Research Biologist

Florida Game and Fresh Water Fish

Commission

Gainesville, Florida 32601

Dennis N. David

Alligator Management Section Leader

Florida Game and Fresh Water Fish

Commission

Gainesville, Florida 32601

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

Hu nt with detachable-head harpoons

or handheld, breakaway pole

snares.

Capture with snatch hooks or tongs.

Identification

The American alligator (Alligator

mississippiensis, Fig. 1) is the most com-

mon of two crocodilians native to the

United States and is one of 22 crocodil-

ian 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.

Fig. 1. American alligator,

Alligator mississippiensis

PREVENTION AND CONTROL OF WILDLIFE DAMAGE — 1994

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

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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, Louisi-

ana, 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 win-

ters north of central Florida and repro-

duce only in southernmost Florida.

Habitat

Alligators can be found in almost any

type of fresh water, but p opulation

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 Geor-

gia, Alabama, and Mississippi. Alliga-

tors commonly inhabit urban wetlands

(canals, lagoons, ponds, impound-

ments, 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, crus-

taceans, small mammals, and birds;

and adults (greater than 6 feet [1.8 m])

eat fish, mammals, turtles, birds, and

other alligators. Diets are range-depen-

dent; 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 82

o

to 92

o

F (28

o

to 33

o

C). They

stop feeding when ambient tempera-

ture drops below 70

o

F (21

o

C) and

become dormant below 55

o

F (13

o

C).

Alligators are among the largest ani-

mals 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 con-

structed of the predominant surround-

ing 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 char-

acterized 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 alli-

gators smaller than 5 feet (1.5 m) in

length are rare.

Contrary to popular belief, few attacks

can be attributed to wounded or terri-

torial alligators or females defending

their nests or young. Necropsies of alli-

gators 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 nor-

mally approach on the surface of the

water where they can be more intimi-

dating. 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 hu mans being

bitten by protective females. Brooding

females typically try to intimidate

intruders by displaying and hissing

before attacking.

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Alligators quickly become conditioned

to humans, especially when food is in-

volved. 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 re-

moved each year following feeding by

humans. Ponds and waterways at golf

courses and high-density housing cre-

ate 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 document-

ed approximately 140 unprovoked

attacks from 1972 to 1991, or about 7

per year. Since 1972, 5 deaths have

been p ositively attributed to alligators.

Historically, nonfatal attacks have also

been docu mented 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 punc-

ture wounds and/or torn flesh. Alliga-

tors, like other crocodilians that take

large prey, prefer to seize an append-

age and twist it off by spinning. Many

serious injuries have involved badly

damaged and broken arms on humans

and legs on animals. Sometimes alliga-

tors bite or eat previously drowned

persons. Coroners can usually deter-

mine 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 exten-

sive burrows or dens for refuges from

cold temperatures, drought, and

predators (other alligators and hu-

mans). Burrowing by alligators can

damage dikes in impoundments.

Legal Status

The American alligator is federally

classified as “threatened due to simi-

larity of appearance” to other

endangered and threatened crocodil-

ians. This provides federal p rotection

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

Alligators are most dangerous in water

or at the water’s edge. They occasion-

ally make overland forays in search of

new habitat, mates, or prey. Concrete

or wooden bulkheads that are a mini-

mum of 3 feet (1 m) above the high

water mark will repel alligators along

waterways and lakes. Alligators have

been documented to climb 5-foot (1.5-

m) chain-link fences to get at dogs.

Fences at least 5 feet high with 4-inch

(10-cm) mesh will effectively exclude

larger alligators if the top of the fence

is angled outward.

Habitat Modification

Elimination of wetlands will eradicate

alligators because they depend on

water for cover, food, and temperature

regulation. Most modifications of wet-

lands, however, are unlawful and

would adversely affect other wildlife.

Elimination of emergent vegetation

can reduce alligator densities by

reducing cover. Check with appropri-

ate conservation authorities before

modifying any wetlands.

Frightening

Aversive conditioning using sticks to

prod “tame” alligators and rough han-

dling of captured alligators have been

attempted in several areas with limited

success. Hunting pressure appears to

be the most effective means of increas-

ing alligator wariness and may be re-

sponsible for limiting the incidence of

alligator attacks in Florida, despite in-

creasing human and alligator pop ula-

tions. The historically low attack rate

in Louisiana is attributed to a history

of intense hu nting.

Repellents

None are registered.

Toxicants

None are registered.

Trapping

Alligators can be readily trapped be-

cause they are attracted to baits. A

baited hook is the simplest method

and is used in Louisiana as a general

harvest method and in Florida to

remove nuisance alligators. Hooks are

rigged by embedding a large fish hook

(12/0 forged) in bait (nutria, fish, beef

lungs, and chicken are popular) and

suspended from a tree limb or pole

about 2 feet (0.6 m) above the surface

of the water. The bait should be set

closer to the water to catch smaller alli-

gators. To increase succ ess, baited

hooks should be set in the evening and

left overnight during the primary feed-

ing time of alligators. Once swallowed,

the hook lodges in the alligator’s stom-

ach and the alligator is retrieved with

the attached rope. This method can kill

or otherwise injure alligators and is not

suitable for alligators that are to be

translocated. Hooked alligators are

most effectively killed by a shot to the

brain with a small caliber (.22) rifle.

Powerheads (“bangsticks”) can also be

used to kill alligators, but should only

be used with the barrel under water

and according to manufacturer recom-

mendations.

Trip-snare traps (Fig. 2) are more com-

plicated and somewhat less effective

than are set hooks but do not injure or

kill alligators. An alligator is attracted

to the bait and, because of the place-

ment of the guide boards, is forced to

enter from the end of the trap with the

snare. The alligator puts its head

through the self-locking snare (No. 3,

72-inch [1.84-m]; see Supplies and

Materials), seizes the bait, and releases

the trigger mechanism as it pulls the

bait. The surgical tubing contracts and

locks the snare on the alligator. These

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traps can be modified as floating sets.

A variation of the trip-snare trap c an

be set on alligator trails and rigged to

trip by the weight of the alligator (see

Mazzotti and Brandt 1988).

Wire box traps have been used effec-

tively to trap alligators. Heavy nets

have been used with limited success to

capture alligators and crocodiles at

basking sites.

Translocation

Translocation of problem alligators

was practiced extensively during the

1970s with limited success. Alligators,

especially larger ones, tended to return

to their original c apture sites after

being moved. These alligators not only

caused problems during their return

trip but frequently required subse-

quent capture and translocation.

Translocation is not recommended

unless areas with depleted alligator

populations are available for release of

problem animals.

Shooting

Next to baited hooks, shooting is prob-

ably the most effective means of

removing alligators. Alligators can be

shot during the day or at night, and

should be shot in the brain case with a

sufficiently powerful rifle (.243 caliber

and larger) for an efficient and

humane kill. Firearms, however, pre-

sent public safety problems in most

nuisance alligator settings. Further-

more, alligators sink almost immedi-

ately after dying and may be difficult

to recover (by gaffs or snatch hooks) in

areas with currents or dense submer-

gent plants. This method may make

confirmation of a kill difficult and may

compromise the commercial value of

the alligator. Crossbows with lines

attached to barbed bolts work fairly

well at short distances but should only

be used to kill alligators.

Other Methods

Detachable-head harpoons (Fig. 3a, b)

with attached lines have been used ef-

fectively to harvest nuisance alligators.

A harpoon assembly (Fig. 3a) is at-

tached to a 10- to 12-foot (3- to 3.5-m)

wooden pole. The harpoon is thrust at

INSERT

6"

See insert

32" surgical

tubing stretched

to 80" when snare

is set

8"

Kleflo ck

No. 2 Snare

Fragile

Twig

20"

WATER

EDGE

Surgical

Tubing

WATER

LINE

Fig. 2. Alligator trip-snare trap.

the alligator and, after the tip pene-

trates the skin, withdrawn, leaving the

tip embedded under the alligator’s

skin (Fig. 3b). As tension is placed on

the retrieval line, the off-center attach-

ment location of the cable c auses the

tip to rotate into a position parallel to

the skin of the alligator, providing a

secure attachment to the alligator. Har-

poons are less effective than firearms,

but the attached line helps to ensure

the recovery of the alligator.

Snatch hooks are weighted multitine

hooks on fishing line that can be cast

over an alligator’s back and embedded

in its skin. The size of hooks and the

line strength should be suited to the

size of the alligator; small alligators

can be caught with standard light fish-

ing gear while large alligators require

10/0 hooks, a 100-pound test line, and

a heavy-duty fishing rod. Heavy hooks

with nylon line can be hand-cast for

larger alligators. After the hook pen-

etrates the alligator’s skin, the line

must be kept tight to prevent the hook

from falling out. Alligators frequently

roll after being snagged and become

entangled in the line. This entangle-

ment permits a more effective recov-

ery. Snatch hooks work well during

the day and at night, provided that

vegetation is minimal.

Handheld poles with self-locking

Smooth Top

Notch

3/16" x 3" wooden

dowel with eyelet

inserted into surgi-

cal tubing

8 P common nail

driven through 1" x 2"

upright and excess

trimmed to 3/4"

F-5

Pe g

(stainless steel)

Tip

(stainless steel)

Base

(aluminum)

Tube

(copper)

Cable

(stainless steel)

a

b

Skin

Muscle

Nylon

rope

Duct tape

(1/2")

Fig. 4. Break-away snare.

snares (sizes No. 2 and 3; Fig. 4) can be

used effectively to capture unwary

alligators at night. For smaller (less

than 6 feet [1.8 m]) alligators, snares

can be affixed to a pole with a hose

clamp. For adult alligators, snares

should be rigged to “break away”

from the pole by attaching the snare to

the pole with thin (1/2-inch [1-cm]

wide) duct tape (Fig. 4). The tape or

clamps allow the snare to be maneu-

vered and are designed to release after

the snare is locked. Carefully place the

snare around the alligator’s neck, then

jerk the pole and/or retrieval line to

set the locking snare. A nylon retrieval

rope should always be fastened to the

snare and the rope secured to a boat or

other heavy object.

For alligators less than 6 feet (1.8 m)

long, commercially available catch

poles (Fig. 5; see Supplies and

Materials) can be used. Snake tongs

(Fig. 6, see Supplies and Materials)

are effective for catching alligators less

than 2 feet (0.6 m) long.

Avoidance

Measures can be taken to avoid con-

frontations with alligators and sub-

stantially reduce the p robability of

attacks. Avoid swimming or partici-

pating in water activities in areas with

large alligators. Avoid water activities

at dusk and at night during the

warmer months when alligators are

most active. Alligators can quickly

surge at least 5 feet (1.5 m) onto the

shore to seize prey, so care should be

taken when at the water’s edge. Do

not feed alligators. Avoid approaching

nests and capturing young (<2 feet

[0.6 m]) alligators.

Economics of Damage and

Control

Alligators can cause injuries and death

to humans, livestock, and pets. All alli-

gator bites require medical treatment

and serious bites may require hospital-

ization. Infections can result from alli-

gator bites, particularly from the

Aeromonas spp. bacteria.

Lawsuits that arise from findings of

negligence on the part of a private

Locking snare (No. 3)

Fig. 3. (a) Detachable-head harpoo n; (b) Rotation of harpo on tip after penetration.

F-6

Acknowledgments

We thank William Brownlee, Texas Parks and

Wildlife Department; Ted Joanen, Louisiana

Department of Wildlife and Fisheries; Steve

Ruckel, Georgia Department of Natural

Resources; Thomas Swayngham, South Caro lina

Department of Wildlife and Marine Resources;

and Paul Moler and Michael Jennings, Florida

Game and Fresh Water Fish Commission for

providing information on their respective states

and for reviewing this chapter. We also thank

Thomas Murphy and Philip Wilkinson, South

Carolina Department of Wildlife and Marine

Resources, for providing diagrams of the trip-

snare trap.

For Additional

Information

Delany, M. F., A. R. Woodward, and I. H.

Kochel. 1988. Nuisance alligator food habits

in Florida. Florida Field Nat. 16:90-96.

Hines, T. C., and K. D. Keenlyne. 1976. Alligator

attacks on humans in Florida. Proc. Ann.

Conf. Southeast. Assoc. Fish Wildl. Agencies

30:358-361.

Hines, T. C., and A. R. Woodward. 1980.

Nuisance alligator control in Florida. Wildl.

Soc. Bull. 8:234-241.

Jennings, M. L., A. R. Woodward, and D. N.

David. 1989. Florida’s nuisance alligator

control program. Proc. Eastern Wildl.

Damage Control Conf. 4:29-36.

Joanen, T., and L. McNease. 1987. The

management of alligators in Louisiana,

U.S.A. Pages 33-42 in G. J. W. Webb, S. C.

Manolis, and P. J. Whitehead, eds. Wildlife

management: crocodiles and alligators.

Surrey Beatty and Sons Pty. Ltd., Chipping

Norton, NSW, Australia.

Mazzotti, F. J., and L. A. Brandt. 1988. A method

of live-trapping wary crocodiles. Herpetol.

Rev. 19:40-41.

Murphy, T., P. Wilkinson, J. Coker, and M.

Hudson. 1983. The alligator trip snare: a live

capture method. South Carolina Wildl. and

Marine Resour. Dep., Columbia. (unpub.

brochure).

Thompson, B. C., L. A. Johnson, D. S. Lobpries,

and K. L. Brown. 1986. Capabilities of

hunters to shoot and retrieve free-swimming

alligators. Proc. Ann. Conf. Southeast. Assoc.

Fish Wildl. Agencies 40:342-348.

Editors

Scott E. Hygnstrom

Robert M. Timm

Gary E. Larson

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, live-

stock losses. Losses of livestock other

than domestic waterfowl, however,

are unc ommon 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 p roducts

such as skulls, teeth, fat, and organs

can be sold, but account for less than

10% of the value of an alligator. Nui-

sance 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 har-

vests about 4,000 alligators per year.

Nuisance alligator harvests also occur

in Louisiana (600), Georgia (400),

South Carolina (250), and Texas (50).

Fig. 5. Commercial catch pole.

Fig. 6. Snake tongs.