REPTILES, AMPHIBIANS, ETC: Alligators
Fig. 1. American
alligator, Alligator mississippiensis
The American alligator
(Alligator mississippiensis, Fig. 1) 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%
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.
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.
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-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 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.
excavate extensive burrows or dens for refuges from cold
temperatures, drought, and predators (other alligators
and humans). Burrowing by alligators can damage dikes in
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.
Prevention and Control Methods
Alligators are most
dangerous in water or at the water’s edge. They
occasionally make overland forays in search of new
habitat, mates, or prey. Concrete or wooden bulkheads
that are a minimum 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
Elimination of wetlands
will eradicate alligators because they depend on water
for cover, food, and temperature regulation. Most
modifications of wetlands, however, are unlawful and
would adversely affect other wildlife. Elimination of
emergent vegetation can reduce alligator densities by
reducing cover. Check with appropriate conservation
authorities before modifying any wetlands.
using sticks to prod “tame” alligators and rough
handling of captured alligators have been attempted in
several areas with limited success. Hunting pressure
appears to be the most effective means of increasing
alligator wariness and may be responsible for limiting
the incidence of alligator attacks in Florida, despite
increasing human and alligator populations. The
historically low attack rate in Louisiana is attributed
to a history of intense hunting.
None are registered.
None are registered.
Alligators can be readily
trapped because 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 alligators. To increase
success, baited hooks should be set in the evening and
left overnight during the primary feeding time of
alligators. Once swallowed, the hook lodges in the
alligator’s stomach 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
Trip-snare traps (Fig. 2)
are more complicated 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
placement 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 traps can be modified as floating sets.
A variation of the trip-snare trap can 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 effectively to trap alligators. Heavy nets have
been used with limited success to capture alligators and
crocodiles at basking sites.
Translocation of problem
alligators was practiced extensively during the 1970s
with limited success. Alligators, especially larger
ones, tended to return to their original capture sites
after being moved. These alligators not only caused
problems during their return trip but frequently
required subsequent capture and translocation.
Translocation is not recommended unless areas with
depleted alligator populations are available for release
of problem animals.
Next to baited hooks,
shooting is probably 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, present public safety problems in most nuisance
alligator settings. Furthermore, alligators sink almost
immediately after dying and may be difficult to recover
(by gaffs or snatch hooks) in areas with currents or
dense submergent 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.
harpoons (Fig. 3a, b) with attached lines have been used
effectively to harvest nuisance alligators. A harpoon
assembly (Fig. 3a) is attached to a 10- to 12-foot (3-
to 3.5-m) wooden pole. The harpoon is thrust at
the alligator and, after
the tip penetrates 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
attachment location of the cable causes the tip to
rotate into a position parallel to the skin of the
alligator, providing a secure attachment to the
alligator. Harpoons are less effective than firearms,
but the attached line helps to ensure the recovery of
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 fishing 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
penetrates 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 entanglement permits a more effective
recovery. Snatch hooks work well during the day and at
night, provided that vegetation is minimal.
Handheld poles with
self-locking snares (sizes No. 2 and 3; Fig. 4) can be
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 maneuvered
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.
Measures can be taken to
avoid confrontations with alligators and substantially
reduce the probability of attacks. Avoid swimming or
participating 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
alligator bites require medical treatment and serious
bites may require hospitalization. Infections can result
from alligator bites, particularly from the Aeromonas
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).
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 Carolina 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
Hines, T. C., and K. D.
Keenlyne. 1976. Alligator attacks on humans in Florida.
Proc. Ann. Conf. Southeast. Assoc. Fish Wildl. Agencies
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,
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.
Scott E. Hygnstrom Robert
M. Timm Gary E. Larson
PREVENTION AND CONTROL OF
WILDLIFE DAMAGE — 1994
Division Institute of Agriculture and Natural Resources
University of Nebraska -Lincoln
United States Department
of Agriculture Animal and Plant Health Inspection
Animal Damage Control
Great Plains Agricultural Council Wildlife Committee