COTTONMOUTH ~ ______________________ G_R_O_U_P_3_:_R_E_PT_I_LE_S_& __ A_M_P_H_IB_IA_N __ S _~~ ... CLASS ~ Reptilia
... ORDER ~ Squamata
... FAMilY ~ Viperidae
GENUS & SPECIES Agkistrodon piscivorus
The cottonmouth is one of the largest poisonous snakes in the United States, sometimes reaching a length of six feet. A deadly
predator, it is also one of the few snakes to eat carrion.
KEY FACTS
SIZE
length: 1 ~-6 feet.
BREEDING
Sexual maturity: About 3 years.
Mating season: Spring or fall.
Gestation: Nearly a year.
No. of young: 1-15.
LIFESTYLE
Habit: Active mainly at night,
when the pit organ is more effec
tively used. Lives alone or in pairs
but hibernates in groups. Range of the cottonmouth.
DISTRIBUTION
Diet: Fish, frogs, turtles, young alli
gators, birds, and mammals.
lifespan: 18-20 years.
RELATED SPECIES
There are 2 other Agkistrodon spe
cies found in North and Central
America: the copperhead, A. contortrix, and the Mexican moccasin,
A. bilineatus. The 10 Asian species
include the Malaysian moccasin,
A. rhodostoma.
The cottonmouth is found in the southern and southeastern
states of the United States, from eastern Texas to Virginia.
CONSERVATION
The cottonmouth's habitat is threatened by the drainage of
swamps and other wetlands. In addition, shooting is drastical
ly reducing the population.
FEATURES OF THE COTTONMOUTH
Body: Thick and muscular. Dark blue-black scales with brown markings that later turn black.
Pit: Heat-detecting organ situated on each side of the face, between the eye and nostril. Detects infrared radiation given off by warm-blooded animals. Enables the cottonmouth to hunt camouflaged prey and track mammals in the dark.
CLASS ... ORDER FAMILY GENUS & SPECIES Reptilia ~ Chelonia Emydidae Chrysemys scripta
The red-eared slider is a sociable turtle found in the southern and midwestern United States. When large numbers bask in the sun, they may climb on top of each other in stacks of three or four.
KEY FACTS
SIZES
Length: Carapace (upper shell),
5-11 in. Female larger than male.
Weight: Up to 2 lb.
BREEDING
Sexual maturity: 2-3 years.
Mating: March to June.
No. of eggs: 2-22 white elliptical
eggs per clutch. Often 2 clutches
per year.
Incubation: 2~-3 months.
LIFESTYLE
Habit: Fairly sociable. Often basks
in large groups.
Diet: Water plants, freshwater fish,
mollusks, and insects.
Lifespan: 40 years.
RELATED SPECIES
The red-eared slider is a subspecies
(race elegans) of Chrysemys scripta,
the pond slider. Two closely related
species are the painted turtle, C. picta, and the red-bellied turtle,
C. rubriventris.
Range of the red-eared slider.
DISTRIBUTION
Found in freshwater ponds and slow-moving streams and rivers
in the United States, from Indiana to Texas.
CONSERVATION
The heavy demands of the pet trade appear to be affecting
wild populations of the red-eared slider. Many red-eared sliders
are raised on turtle farms, but few of them reach adulthood.
FEATURES OF THE RED-EARED SLIDER
Head: Distinctive red patches behind eyes. Mouth has powerful jaws, with toothless sharp edges that tear food into pieces.
Young: Green at first. Gains brown or black blotches as it matures.
Carapace: Domed upper part of the shell, covered with horny plate. Color and markings vary.
Plastron: Bony lower part of the shell . Joined to the carapace.
Hind limbs: Strong and muscular. Feet have claws for tearing food and are partially webbed for swimming.
0160200791 PACKET 79
The red-eared slider is named for the way it slides
into the water and for the broad red stripe behind
each of its eyes. The red stripe looks somewhat like an
ear, and it is most noticeable in young adult males.
On occasion, however, the stripe may be yellow.
~ HABITS The red-eared slider prefers an undisturbed pond or a quiet stretch of slow-moving fresh water that has a muddy bottom and plenty of thick vegetation surrounding it.
Like many other freshwater chelonians (terrapins, tortoises, and turtles), the slider spends hours out of the water during spring and summer. After hauling itself onto a log or rock, it warms its body by basking in the sun. If disturbed, it retreats into the safety of the water. In some areas there are so many red-eared sliders sunbathing that they climb on top of each other in stacks of three or four.
Right: The red-eared slider and other pond sliders quickly slide into the water when alarmed.
~ BREEDING When the temperature begins to rise in the spring, the redeared slider is ready to mate. The male waves the long claws on his forefeet in the face of the female to stimulate her to mate. As he clambers onto the female, his claws help him grip her carapace (upper shell).
In early summer the female chooses a nest site near the water's edge, just above the
Left: The red-eared slider emerges from its food-rich waters and basks in the sun on land.
DID YOU KNOW? • Melanism (the development of dark pigment) is common in the red-eared slider. Black streaks, spots, and blotches appear on both the upper and lower shells and spread
high-water mark. After digging out the nest with her hind legs, she lays 2 to 22 white eggs with leathery shells. She sometimes lays two clutches in a year.
After they hatch, the young sliders grow rapidly, reaching two or more inches by their second year. They then grow about a half-inch each year until they reach the adult size of up to 11 inches.
Right: The female carefully chooses a nest site on land in which she lays her eggs.
over the original shell pattern. In some cases, the shell becomes a uniform brown. •• For the slider to be buoyant in water, 14 percent of its total body volume must be air.
~ FOOD & FEEDING The red-eared slider eats plants and animals. Fibrous green water plants are its main food, but it may also catch worms, small freshwater fish, mollusks, and aquatic insects, which it swallows whole.
Like other chelonians, the redeared slider lacks teeth. It tears up large pieces of food using its foreclaws. To chew, it uses the sharp cutting edges inside its mouth, which are moved by strong jaw muscles.
~ RED-EARED SLIDER & MAN Because of cartoon series about the Teenage Mutant Ninja Turtles, the red-eared slider was a popular pet in the late 1980s. At the craze's peak in 1988, two million sliders were exported from the United States, mainly to western Europe.
Most red-eared sliders die in captivity, mainly because their
owners are unaware of their requirements. The few that do survive mature rapidly and become large and messy. Some become snappish and cannot be kept at home. Many people simply dump their unwanted pets in the country, where they may die from cold or the lack of suitable food.
Left: Buying a young redeared slider as a pet may not be a good idea because it often carries Salmonella bacteria. In addition, the pet trade is a threat to sliders in the wi/d.
GRASS SNAKE
CLASS Reptilia
ORDER Squamata
~CARD40
GROUP 3: REPTILES & AMPHIBIANS
~ FAMILY "11IIIIIIII Colubridae
GENUS fir SPECIES Natrix natrix
One of the largest and most common snakes in Europe, the grass snake is harmless to humans. Also known as the water snake,
it is equally at home in the water and on land.
KEY FACTS
SIZE
Length: Male, about 2~ ft. Fe
male, 3-3~ft. Longest recorded,
6~ft.
BREEDING
Breeding season: April to July.
Sexual maturity: 5 years.
No. of eggs: 30-40, increasing
with the age of the female.
Hatching time: 6-10 weeks.
LIFESTYLE
Habit: Day-active in damp areas.
May hibernate with several others.
Diet: Frogs, newts, fish, and small
mammals. Young feed on insects
and other invertebrates.
Range of the grass snake.
DISTRIBUTION
lifespan: About 9 years.
RELATED SPECIES
The grass snake is found in Great Britain, east across Europe
and Asia as far as Mongolia, and south to the northwestern
coast of Africa.
CONSERVATION The grass snake's closest relatives
are the water snakes of the genus
Nerodia of North America. Steady loss of habitat is causing a reduction in the grass snake
population. Although the animal is already less common than
in the past, it is not yet endangered.
HOW THE GRASS SNAKE EATS ITS PREY
The grass snake seizes prey in its jaws, then works it into its mouth very gradually. Its jaws are loosely hinged and very elastic. While gripping its victim with its small teeth, the snake "walks" its jaws forward one side at a time. Slippery prey such as a frog is easy to
Markings: Irregular dark markings on a brown or olive-green background.
work into the mouth. But to swallow furry prey, 1Ifii~;r~~~~ the snake produces large amounts of saliva ~ to ease passage through its mouth.
Head: Yellow collar around neck gives the animal its alternative name of ringed snake. Black eyes; round pupils.
The grass snake is not poisonous, but it is often mistaken
for the venomous adder. As a result of this confusion, many
grass snakes are killed. Although there are some similarities
between them, it is quite easy to tell the difference between
the harmless reptile and the toxic animal. Their markings
are noticeably different, and the grass snake can
sometimes be twice as long as the adder.
~ HABITS The grass snake is active by day in damp places in hedgerows, marshes, and woods. It sleeps at night in a dry, sheltered spot. It spends much of its time basking in the sun and it may climb into a shrub late in the day to catch the last rays of the sun.
In the cold parts of its range the grass snake hibernates for the winter in an empty burrow, hollow log, or hole in a bank or tree. Sometimes several snakes hibernate together.
The grass snake is preyed on by badgers, hedgehogs, and birds of prey. It has no venom-
ous bite to use as a defense, but its coloring makes it difficult to detect in the undergrowth, and it can move very fast.
When threatened, the snake strikes as if it were venomous. But it keeps its mouth closed, inflates its body, and hisses. If this does not succeed, it then produces a foul-smelling liquid from glands at the base of its tail. If the predator still does not go away, the grass snake may play dead by lying on its back with its head flopped to the side, its mouth open, and its tongue hanging out.
~ BREEDING The grass snake mates in April or May. To court a female, the male approaches her while nodding his head and then rubs his chin along her back.
The female lays up to 40 eggs in June or July. In colder regions she finds a warm place such as a manure heap, haystack, or pile of rotting leaves and makes a nest by burrowing into the soft material. Or she uses a natural hole and enlarges it by twisting her body around. Sometimes
Left: A dead grass snake is not an appealing meal, so playing dead is a good defense.
10 10 YOU KNOW?
• It is said that the grass snake I drinks milk from the udders of
cows and goats, but this is just folklore . The snake will drink milk in captivity, but only if it is the only liquid available. • A grass snake found swimming 25 miles from shore in the Bay of Biscay was not hurt by the salt water.
several grass snakes will use the same site.
The female does not remain with her eggs or look after the young. The eggs may hatch after 6 weeks in warm weather or take up to 10 weeks. The young snake is about six inches long. It has an egg tooth on its snout, which it uses to tear its way out of the leathery shell. The egg tooth drops off in a few hours. The young then eats worms and other small invertebrates.
Right: The eggs all hatch at about the same time, and the young go off to find food.
II The grass snake is one of the few snakes that can be found inside the Arctic Circle. It also lives at altitudes of over 7,200 feet in the Alps. " Great Britain has three species of snakes, but Ireland has none at all. According to Irish legend, Saint Patrick rid the island of snakes.
[ \..;~~ NATUREWATCH The grass snake is often mistaken for a poisonous adder. Although the two snakes look similar, the grass snake has a yellow collar, round pupils, and irregular dark markings. The adder has no collar, its pupils are slitted, and a zigzag
~ FOOD &: HUNTING The grass snake feeds on frogs, newts, fish, lizards, and small mammals such as mice. It also eats birds and their eggs and chicks. It consumes very large meals that sustain it for days and can go for a week without food if inactive.
The snake hunts on land and in water. It swallows small prey underwater but takes larger animals onto land. It locates prey by flicking its tongue to pick up scents in the air. It catches prey
Left: With its jaws open wide, the grass snake slowly works prey into its mouth.
pattern runs down its back. The grass snake can be seen
on damp ground near fresh water or on the surface of a pond. In cold areas it can only be seen from May to September, since it hibernates from October to April.
by gliding as close as possible, then lunging forward to seize the victim in its teeth.
The grass snake's elastic jaws are loosely joined and are able to move separately. The snake usually moves its prey until its mouth is over the head. It swallows the animal whole by mov
ing alternate sides of its jaws forward over its victim. It produces a large amount of saliva to ease the operation.
A big meal takes some time to digest, so the grass snake rests in a quiet place while its food goes down.
~ARD44 J ~TTERJACK TOADGROUP 3: REPTILES &; AMPHIBIANS ~ ~ CLASS ORDER FAMILY ~ GENUS & SPECIES ,.,~
The natterjack toad burrows into coastal dunes and sandy heaths in much of Europe. It has rapid reflexes, snatching and then eating almost any small animal it encounters.
KEY FACTS ----~I---
SIZE
Length: Normally, up to 2Z1 in.;
rarely, up to 3 in . Female usually
larger than the male.
BREEDING
Sexual maturity: 2-4 years.
Breeding seas6n: April to July.
Hatching time: 5-8 days.
Tadpole stage: 6-8 weeks.
LIFESTYLE
Habit: Solitary, active at night.
Usually land-dwelling, but lives in
ponds while breeding. Hibernates
during winter.
Diet: Small live prey such as in
sects, worms, and snails.
Call: Male croaks when courting.
Lifespan: 15-16 years.
RELATED SPECIES
The natterjack toad's relatives in
clude the wide-ranging Europe
an toad, Bufo bufo; the American
toad, B. american us; and 1 7 other
toad species in North America.
Range of the natterjack toad.
DISTRIBUTION
Found in much of continental Europe from Spain north to the
Netherlands, Germany, Denmark, Sweden, Estonia, Latvia, and
Lithuania. It is rare in Great Britain and Ireland.
CONSERVATION
The natterjack toad is in decline throughout its range, mainly
because of habitat destruction.
FEATURES OF THE NATTERJACK TOAD
Skin: Dry, shiny, and warty. Yellowish olive-green with green patches. Laced with glands that secrete a bad-tasting
poison to deter predators. A yellow
Eyes: Pupils are fully rounded at night to absorb qS much light as possible. During the day they narrow to slits. :;;.~~~~~j~~~,".striPe down its back distinguishes it
~~~It~S~~~~~~~~:~~~~1 from the European toad.
Voice: In the breeding season males call from their spawning
l ponds. They may continue their rattling , trilling croaks throughout the night.
Forefeet: May be used for digging in areas with firm soil. A breeding male develops pads on his first three fingers to improve his grip on the female .
Hind limbs: Comparatively short for I a toad, enabling it to run with
surprising speed. Its digits are partially webbed. J
0160200921 PACKET 92
The natterjack is a small, burrowing relative of the
European toad. In some parts of its range it has suffered
greatly from the conversion of its heath land habitat into
modern farms. It has also been affected by urbanization.
Even though it is still widespread in much of continental
Europe, it is now an endangered species in Great Britain.
~ HABITS In winter the natterjack toad remains in its burrow, insulated from the cold by up to two feet of soil or sand. When spring temperatures rise to about 54 0 F, it rouses and digs to the surface.
Although the natterjack is active mostly at night, it may venture out on a dry day. Known as the "running toad," it prefers to crawl or run and rarely hops. It is a skilled climber and can scuttle over sand dunes. But com-
pared with other toads or frogs, the natterjack is a bad swimmer. It visits water only when necessary, in order to breed.
The natterjack often lives in areas with sandy, loose soil that it can dig easily. It uses its short hind legs to burrow in sand but employs its forelimbs to scoop out a retreat on firmer ground.
Right: After absorbing their tails, tadpoles move onto land as tiny toads under half an inch long.
~ FOOD & HUNTING The natterjack toad eats small animals such as insects, spiders, slugs, snails, and worms. As a tadpole, it may even eat other tadpoles if food is scarce.
The natterjack usually hunts at night, attacking anything that moves. Once the toad's attention is caught, it watches briefly. If the prey stops moving, the toad may lose interest. But if the animal twitches, the natterjack
~ DEFENSES Poison glands in the natter-jack's skin give it a bad taste, but this does not always stop predators. Crows rip off the skin, while herons, foxes, and snakes eat the toad anyway.
Left: In early spring the male natterjack toad swells his vocal sac and sings to attract a mate.
DID YOU KNOW? • The natterjack toad has been known to climb a steep sandbank and spend the winter in the burrow of a bank swallow. Several toads may huddle together in a big burrow. • During the spawning season, small "satellite" males some-
flicks out its sticky tongue and quickly snatches its victim.
Because the toad swallows its food whole, the size of its prey is limited by the size of the toad's mouth. After crushing its victim, the toad retracts its eyeballs toward the roof of its mouth to force its meal down its throat.
Right: The natterjack toad is alert to signs of live preYt reacting to the slightest movements.
The natterjack has other defenses. To deter a rat, the toad may fill its body with air so that it appears larger. At the same time it raises its rump to present the poison glands on its back. To deceive a heron, the toad may lie flat on the ground and pretend to be dead.
times lurk silently near a pond where other males are calling and intercept females on their way to their suitors. • The natterjack is often found close to reeds, and its scientif-ic name derives from calamus, I the Latin word for a reed. ~
[>, l ;'~ NATUREWATCH The natterjack toad is slightly smaller and greener than the European toad . It is easily distinguished from this related toad by the yellow line down its back.
Because the natterjack usual-
~ BREEDING The natterjack toad lives mostly on land but returns to water to breed. It actually mates in water, since the male just sheds sperm over the female's eggs and the eggs must stay moist to survive.
Cloudy, mild weather in early spring prompts males to head for shallow, warm ponds, where they prefer to breed. They croak to attract females within a radius of a half-mile or more.
The breeding male develops
Left: The male natterjack does not internally fertilize the female's eggs. Instead, he mounts her, gripping her firmly while she spawns. This mating act is referred to as amplexus.
Iy forages at night, it is rarely seen in daylight. Rather than hopping, it normally runs on its short legs. If it is alarmed, it may try to burrow quickly out of sight, scooping out sand J like a dog burying a bone.
thick pads on his first three fingers, so he can grip the female and fertilize her eggs as she lays them. Each season she produces up to 4,000 eggs in jelly strings over three feet long. The strings wrap around water plants.
The tadpoles hatch in five to eight days. They are oval with long tails but in a few weeks develop hind legs, then forelegs . Finally they absorb their tails and move to dry land.
LEATHERBACK TURTLE ) GROUP 3: REPTILES £< AMPHIBIANS ~ ... FAMILY GENUS & SPECIES ~ Oermochelyidae Oermochelys coriacea
CLASS ORDER Reptilia Chelonia
The leatherback turtle is the biggest turtle in the world. This hardy reptile wanders in tropical as well as temperate oceans.
It spends most of its life feeding far from land.
'\J KEY FACTS
I~ I SIZES ~ Shell length: Up to 7 ft.
Weight: Up to 1,600 lb .
LIFESTYLE
Habit: Solitary, oceanic.
Diet: Large planktonic animals like
jellyfish and siphonophores. Also
mollusks and crustaceans.
Lifespan: Unknown, but probably
quite long.
BREEDING
Mating: At sea.
Egg laying: On traditional breed
ing beaches.
Eggs: Up to 1,000 per season. Laid
in batches of 50 to 170.
Incubation: Several months.
RELATED SPECIES
The leatherback is the only species
in its family. The other family of
true sea turtles, the Cheloniidae,
includes the green, ridley, and
loggerhead turtles.
• Range of the leatherback turtle.
DISTRIBUTION
Widespread but scattered throughout the oceans of the world.
Not found in the polar regions.
CONSERVATION
The leatherback turtle is classified as an endangered species.
Populations that breed on well-known beaches are threatened
by the collection of eggs by local people. The development of
tropical beaches for tourism is also a problem.
FEATURES OF THE LEATHERBACK TURTLE
Ridges: 7 raised ridges run the length of the carapace, or top covering. There are 5 on the plastron, or bottom part of the covering.
Foreflippers: Very powerful. The turtle uses them for swimming and digging but may occasionally lash out in defense. Winglike and tapering, the flippers may span 11 feet.
Carapace: The structure of this massive, tapering covering is unique among turtles. Instead of horny scutes (outer plates) , there is a thick, leathery skin. Instead of
internal bone plates, there are many small , linked
bones supporting a cartilage "shell."
0160200841 PACKET 84
The leatherback turtle is unusual because it does not have
a stiff shell. Instead, this marine giant has a lightweight
structure of cartilage that is covered with leathery skin and
reinforced with tiny bones. This structure gives the turtle
surprising mobility in the water. However, the leatherback
must return to land to lay its eggs, and on the beaches it
faces interference from egg collectors as well as tourists.
~ CHARACTERISTICS The huge leatherback is clearly a turtle, but it lacks the one feature that is common to nearly all other turtles and tortoises: a rigid, horny shell. The bodies of most turtles are encased in a two-part boxlike armor. The top part is called the carapace, and the bottom part is called the plastron. Each is made up of an outer layer of thick, horny scutes (plates) bonded to an inner layer of bony plates. The inner plates are fused to the ribs and backbone to form a rigid unit. Only the turtle's tail, legs, and head are free to move.
Judging from fossil remains, ancestors of the leatherback
turtle had shells of this type. However, over years of evolution, the leatherback replaced the horny scutes with a thick, leathery skin. Instead of bony inner plates, it developed tiny interwoven bones that support a fake shell of flexible cartilage.
This structure is much lighter than a rigid shell. As a result, the turtle is more buoyant in water and uses less energy to swim . Although the lack of a hard shell makes it vulnerable, few predators are big enough to attack it.
Right: The three-inch-Iong hatchlings are covered with scales, which they shed as they mature.
~ FOOD & FEEDING The leatherback uses its winglike forelimbs to "fly" through the water. But it cannot swim fast enough to pursue swift fish and squid. It generally feeds on less agile prey such as jellyfish and comb jellies, as well as other large creatures that drift with the plankton near the surface.
Although these animals are large, they consist mostly of water and are not as nutritious as fish of similar size. The turtle
Left: The leatherback visits land to lay its eggs, which it buries in sand.
DID YOU KNOW? • The leatherback travels great distances. One turtle that was tagged in Suriname turned up on the other side of the Atlantic over 4,200 miles away. • The leatherback may not nest for several years. But then it lays up to nine clutches with more than 80 eggs in each. • Because it is an open-sea
must eat great numbers to get the nourishment it needs.
The leatherback seems to be immune to the poisons that these animals use to catch their own prey. Many possess stinging cells, and several jellyfish species can paralyze and kill large fish . Yet the turtle apparently snaps them up without suffering. The leatherback may, however, avoid species that have the strongest poisons.
Right: Long spines in its mouth help the leatherback swallow food.
species, the leatherback does not adapt to captivity. The turtle never learns to avoid the walls of its tank. • Several of the eggs in each leatherback clutch are malformed and do not hatch. • This turtle is found in waters near Iceland in the north to New Zealand in the south.
~ SPECIAL ADAPTATIONS Turtles obtain body heat from the environment rather than generating their own heat, so most sea turtle species live only in warm tropical waters.
The leatherback has a greater range because of the insulating fat under its skin and the
~ BREEDING The leatherback spends most of its life at sea but returns to land to breed. Until recently its nesting sites were unknown, but several breeding beaches have now been found in the tropics. The turtle prefers beaches facing deep water and avoids sites that are protected by coral reefs. It will swim through heavy surf to reach a good location.
After mating at sea, the female comes ashore at high tide, frequently at night. She crawls up the beach to a point where the sand is moist but beyond the waves' reach. She may excavate a few trial pits before digging in earnest with her flippers.
heat-exchange system in its forelimbs. Heat is transferred from warm blood exiting the heart to cooler blood entering the heart-conserving heat in the body. These adaptations and its big size keep the turtle warm in waters as cool as 54°F.
When the nest hole is deep enough, she starts to lay 50 to 170 large, round eggs. She guides them into the hole with her hind limbs and covers them with sand. Then she returns to the sea, hiding her tracks by zigzagging across the beach.
The eggs develop over several months. When the young turtles hatch, they climb out of the nest and scurry off to the sea . Many never make it. They are easy targets for such predators as skuas, gulls, and ghost crabs. But a few do survive and grow to maturity. Many years later they return to the same beach to produce the next generation.
COMMON GARTER SNAKE
... CLASS ~ Reptilia
.... ORDER ~ Squamata
GROUP 3: REPTILES &: AMPHIBIANS
FAMILY Colubridae
... GENUS &: SPECIES ~ Thamnophis sirtalis
The common garter snake is the most widespread snake in North America. This harmless, graceful creature is unusually sociable and
lives in large groups that contain several hundred individuals.
"J KEY FACTS
I~ I SIZE ~ Length: Usually 2-2 y'; ft. Male
smaller than female .
BREEDING
Sexual maturity: 2-3 years.
Breeding season: Spring.
No. of young: 12-80.
Incubation: 3 months.
LIFESTYLE
Habit: Sociable, living in large
groups of several hundred indi
viduals. Torpid in winter.
Diet: Frogs, toads, fish, salaman
ders, earthworms, small mammals
and birds, carrion.
Range of the common garter snake.
DISTRIBUTION Lifespan: Up to 12 years.
RELATED SPECIES The common garter snake is found from southern Canada
through the United States southward to Central America.
CONSERVATION There are 22 species in the genus
Thamnophis, of which 13 occur in
the U.S. and Canada. Among the
more widespread are the eastern
ribbon snake, T. sauritus, and the
western terrestrial garter snake,
In general the common garter snake appears to be in no dan
ger. But one subspecies-the San Francisco common garter
snake-has been affected by habitat disturbance and is now
listed as endangered.
T. terrestris . .
FIVE SUBSPECIES OF THE COMMON GARTER SNAKE
Eastern common garter snake, Thamnophis sirtalis sirta/is: Common across eastern U.S. Usually striped . May also be spotted or plain.
San Francisco garter snake , T. s. tetra taenia: Restricted to San Mateo County. Threatened by habitat disturbance. Red ,
orange, black, and yellow stripes.
Texas garter snake , T. s. annectans: ' Inhabits eastern
Limited to coast of northern Florida. Blue lateral stripes.
Lives along coast north
of Baja. Red spots
and pale lateral stripes.
0160200971 PACKET 97
The common garter snake is found in a variety of North and
Central American habitats. Although the different subspecies
vary in color and size, many have three light stripes and a
checkered pattern. These markings resemble the patterns on
the old-fashioned garters once used to hold up men's socks.
~HABITS The common garter snake lives
in southern Canada, most of the
United States, and parts of Mex
ico and Central America. It is of
ten found near water such as a
pond or stream. It is also seen in
city parks and gardens, since it
is well adapted to humans.
Like other reptiles, this snake
relies on outside sources to raise
its body temperature. Active by
day, it hides at night beneath a
fallen tree or in a deep hole or
rock crevice.
Right: An excellent swimmer, the common garter snake can remain submerged for a long period. It is at home on land as well as in the water.
At the onset of winter, a large
group of common garter snakes
gathers in a communal shelter
called a hibernaculum, which is
in a rock crevice, ground hole,
or empty burrow. The snakes
spend the winter in a sluggish
or inactive state called torpor. Periodically, the common gar
ter snake molts, shedding its out
er layer of skin as it grows. This
process usually occurs immedi
ately after the snake emerges
from its winter torpor.
~ FOOD & HUNTING Unlike other snake species, the
common garter snake cannot
immobilize large prey with any
venom or by coiling itself tightly
around the animal's body. As a
result, it preys only on small ani
mals such as fish, frogs, toads,
salamanders, and earthworms.
Its diet also includes small mam
mals and birds as well as carrion (dead animal flesh).
Left: Although harmless, common garter snakes are killed because people think they are poisonous.
The garter snake senses the
approach of prey by repeatedly
flicking out its forked tongue to
pick up chemical molecules in
the air. The chemicals are ana
lyzed in the snake's Jacobson's
organ, a pair of pockets located
in the roof of the mouth.
The common garter snake is
generally an active hunter. It of
ten searches for its prey among
vegetation. It takes a victim with
a single lunge, seizing the ani
mal behind the head.
DID YOU KNOW? • The longest common garter
snake on record measured al
most four and a half feet.
• The common garter snake
can survive farther north than
almost any other snake spe-
~ BREEDING Common garter snakes mate in
spring, not long after emerging
from their winter torpor. A num
ber of males compete for a fe
male by wrapping themselves
around her, but only one male
succeeds in fertilizing her. After
mating, the male and female
go their separate ways.
The female common garter
snake is ovoviviparous (giving
Left: The common garter snake requires warmth, so it lives in a communal den during winter.
Left: Because it does not have venom and is unable to constrict big prey, the common garter snake feeds on a variety of small animals. It eats anything it can easily subdue on land or in water.
cies. It can even be found in
sub-Arctic areas of the Yukon.
• There is a Native American
superstition that the year's first
thunderclap brings the garter
snake out of its winter torpor.
birth to live young). The fertil
ized eggs stay in her body until
they are ready to hatch, at the
end of a period of about three
months. She is a prolific breed
er, usually producing up to 60
young in a single brood. The
number may rise to 80 if it is a
warm year with plenty of food.
The young snake is left on its
own from the minute it is born.
It grows rapidly during its first
two years and is ready to mate
when two to three years old .
Left: At mating time, several male common garter snakes wrap themselves around a female and sometimes become knotted together in the process.
