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Lifespan, longevity, and ageing

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Maximum longevity: 14 years (captivity)
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Reproduction

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These snakes begin mating in the spring as soon as they emerge from hibernation. The males leave the den first and wait for the females to exit. Once the females leave the den the males surround them. The males give off pheromones that attract the females. After the female has chosen her mate and mated, she returns to her summer habitat to feed and to find a proper birth place. However, the males stay to re-mate with other available females. The females have the ability to store the male's sperm until it is needed and thus a female may not mate if she does not find a proper partner.

Mating System: polygynandrous (promiscuous)

Common garter snakes are ovoviviparous (bearing live young). The young are incubated in the lower abdomen, about half way down from the snake's body. Gestation is usually two to three months. Most females in the northern parts of their range give birth to from 4 to 80 young between late July and October. Most litters range from 10 to 40 young and litter size depends on the size of the female, with larger females giving birth to larger litters. Upon birth, baby garter snakes are independent and must find food on their own.

Common garter snakes become sexually mature at 1.5 years (males) or two years (females).

Breeding interval: Common garter snakes breed once each year.

Breeding season: Common garter snakes breed in the spring and give birth to their young in late summer.

Range number of offspring: 4 to 80.

Average number of offspring: 10 to 40.

Range gestation period: 2 to 3 months.

Average age at sexual or reproductive maturity (female): 2 years.

Average age at sexual or reproductive maturity (male): 1.5 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; sexual ; fertilization ; ovoviviparous ; sperm-storing

Average age at sexual or reproductive maturity (male)
Sex: male:
730 days.

Average age at sexual or reproductive maturity (female)
Sex: female:
730 days.

Female common garter snakes nurture their young in their bodies until they are born. The mother gives birth to live young, she doesn't lay eggs. Newly born snakes tend to stay around their mother for several hours or days but she provides no parental care or protection after they are born.

Parental Investment: pre-hatching/birth (Provisioning: Female, Protecting: Female)

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Ryan Zimmerman, Western Maryland College
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Untitled

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Some of the subspecies of common garter snakes (Thamnophis sirtalis) are: Thamnophis sirtalis semifasciatus (Chicago Garter Snake), Thamnophis sirtalis parietalis (Red-sided Garter Snake), Thamnophis sirtalis dorsalis (New Mexico Garter Snake), Thamnophis sirtalis annectens (Texas Garter Snake), Thamnophis sirtalis similes (Blue-stripe Garter Snake), Thamnophis sirtalis pallidulus (Maritime Garter Snake), Thamnophis sirtalis fitchi (Valley Garter Snake), Thamnophis sirtalis infernalis (California red-sided Garter Snake), and Thamnophis sirtalis tetrataenia (San Francisco Garter Snake). All of these subspecies are similar, but vary in details of coloration and geographic distribution.

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Behavior

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Common garter snakes communicate with each other primarily through touch and smell, especially for breeding. Outside of the breeding season they do not interact much with other snakes. They use their forked tongues to collect chemicals from the air and insert these forks into a special organ in the roof of their mouth, which interprets these chemical signals, called pheromones. Pheromones can be used as a tracking device for garter snakes. Using their acute sense of smell, common garter snakes can locate other snakes or trails left behind by other snakes through the pheromones given off by their skin. After they are born, baby snakes follow the same pheromone trails to feed and locate other common garter snakes. Snakes are also sensitive to vibrations and have reasonably good vision.

During the breeding season, common garter snakes use complex systems of chemical communication. Male common garter snakes use skin lipids as pheromonal cues for sex recognition because female and male skin pheromones are extremely different. However, some males are occasionally born with both female and male skin pheromones. During mating season these males with female pheromones are courted by other males. The confusion often allows the males with female pheromones to mate first because the other males are courting the wrong sex. Shine et al. (2000) hypothesized that the behavior could provided a mating advantage to the genetically altered males.

Communication Channels: tactile ; chemical

Other Communication Modes: pheromones

Perception Channels: visual ; infrared/heat ; tactile ; vibrations ; chemical

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Ryan Zimmerman, Western Maryland College
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Conservation Status

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Common garter snakes are some of the most common and abundant snakes throughout the eastern United States, at least partly because they do well in urban and suburban areas. Despite the fact that they are harmless snakes, they are often persecuted by humans. Pesticide use in some areas has significantly reduced common garter snake populations. Habitat destruction and over-collection for the commercial pet trade have also led to a decline in the number of garter snakes in the wild. Water pollution is a problem for this species, because so much of its food is aquatic. Northern populations are more vulnerable than southern ones, because they hibernate in larger groups (which are easily harvested) and produce smaller numbers of young each year. It is important to continue to monitor populations of 'common' species as declines in their populations can tell us a great deal about environmental health.

One subspecies, the San Francisco garter snake, Thamnophis sirtalis tetrataenia, is considered endangered, and placed on the US and California Endangered Species list in 1967. Other subspecies may be protected by state laws.

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Ryan Zimmerman, Western Maryland College
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Life Cycle

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The young grow quickly and become mature in their second or third year, when they reach about 55 cm in length. Growth continues throughout the lifespan of these snakes.

Development - Life Cycle: indeterminate growth

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Benefits

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On very rare occasions people have been known to have allergic reactions to common garter snake saliva after handling one and being bitten. These are extremely rare, though, and their reputation as harmless snakes is well deserved.

Negative Impacts: injures humans (bites or stings)

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Benefits

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Common garter snakes act to control populations of insect and mollusk pests. They are a common and welcome sight to many gardeners. They also tame easily and are sometimes kept as pets.

Positive Impacts: pet trade ; controls pest population

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Associations

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Garter snakes are low-level predators, feeding on many small animals and in turn being eaten by other predators higher in the food web. These snakes are one of the few kinds of animals that can eat toads, newts, and other amphibians with strong chemical defenses.

Common garter snakes are infected by a parasitic nematode that lives in the tissues of their tail. Snakes with this condition often have shortened or stubby tails. The nematodes live part of their lifecycle in small aquatic crustaceans and in amphibian larvae. The snakes are infected when they eat the amphibian larvae.

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Trophic Strategy

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Common garter snakes typically eat earthworms, amphibians, leeches, slugs, snails, insects, crayfish, small fish and other snakes. They seem immune to the toxic skin secretions of toads and can eat them without harm. Occasionally small mammals, lizards, or baby birds are eaten as well. Common garter snakes find their prey using their excellent sense of smell and their vision. They use several different hunting methods, such as peering, craning, and ambushing to capture their prey. The different techniques describe the way the snakes move while they hunt. They immobilize their prey using their sharp teeth and quick reflexes. The saliva of common garter snakes may be slightly toxic to some of their small prey, making it easier to handle them while they are being eaten. Like other snakes, they swallow their food whole.

Animal Foods: birds; mammals; amphibians; reptiles; fish; insects; terrestrial non-insect arthropods; mollusks; terrestrial worms; aquatic crustaceans

Primary Diet: carnivore (Eats terrestrial vertebrates)

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Ryan Zimmerman, Western Maryland College
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Distribution

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Common garter snakes are native to the Nearctic region only. They occur throughout much of North America, although they are largely absent from the arid southwestern United States. Common garter snakes are found throughout eastern North America from Florida to coastal Quebec, west to British Columbia, south into southern California east of the Sierras, and throughout the less arid areas of the southwest. Isolated populations occur on mountain ranges in New Mexico and northern Mexico (New Mexico garter snakes, Thamnophis sirtalis dorsalis). They are found as far south as the Gulf of Mexico in the eastern United States.

Biogeographic Regions: nearctic (Native )

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Ryan Zimmerman, Western Maryland College
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Habitat

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Common garter snakes are very widespread, highly adaptable and can survive extreme environmental conditions. Common garter snakes are found in a wide variety of habitats, including meadows, marshes, woodlands, and hillsides. They tend to prefer moist, grassy environments. They are often found near water, such as near the edges of ponds, lakes, ditches, and streams, and are common in suburban and urban areas with plenty of cover (debris, boards, vegetation, logs, or rocks).

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: savanna or grassland ; forest

Wetlands: marsh ; swamp

Other Habitat Features: suburban ; agricultural ; riparian

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Life Expectancy

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The average lifespan of wild common garter snakes is approximately two years. Most common garter snakes probably die in their first year of life. Common garter snakes reach sexual maturity, and maximum size, at 3 to 4 years of age. The lifespan of common garter snakes kept in captivity is longer, between 6 and 10 years. One captive common garter snake lived to be 20 years old, but few wild snakes live this long.

Average lifespan
Status: wild:
2 years.

Range lifespan
Status: captivity:
20 (high) years.

Average lifespan
Status: captivity:
6-10 years.

Typical lifespan
Status: captivity:
6 to 20 years.

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Morphology

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Common garter snakes are highly variable in color pattern. They typically have three light stripes that run along the length of their body on a black, brown, gray, or olive background. The stripes can be white, yellow, blue, greenish, or brown. One stripe runs down the center of the snake's back, the other two stripes run alongside this central stripe. Sometimes the stripes are absent or poorly defined. Some garter snakes have alternating rows of dark spots that run along the stripes, making the stripes look more like checkerboard patterns of light, rather than lines. Common garter snakes have a head that is wider than the neck and is uniformly dark. Their tongues are red, tipped in black, and their scales are keeled (with a raised ridge along the length of the scale). The chin, throat and belly resemble the stripes in coloration, ranging from white to yellow, greenish, blue, or brown.

Common garter snakes grow to be 46 to 137 cm in total length. Males are generally smaller than females and have longer tails. Young common garter snakes are born at 12.5 to 23 cm long and are similar in appearance to the adults. There are many dozens of recognized regional populations of common garter snakes that have distinct color patterns. In some areas there are populations that have a high percentage of entirely black garter snakes. Common garter snakes are similar in appearance to their close relatives, ribbon snakes (Thamnophis sauritus) and Butler's garter snakes (Thamnophis butleri).

Range length: 46 to 137 cm.

Average length: 88.00 cm.

Other Physical Features: heterothermic ; polymorphic

Sexual Dimorphism: female larger; sexes shaped differently

Average mass: 150 g.

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Associations

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Common garter snakes are eaten by a wide variety of predators, which varies throughout their range. Large fish, bullfrogs, snapping turtles, milk snakes, American crows, hawks, great blue herons, raccoons, foxes, squirrels, and shrews are some of the animals that prey on common garter snakes. They rely on stealth and camouflage for protection, and will flee into water to escape predators on land. Their stripes make them difficult to see properly and capture in grassy areas. If unable to flee they coil to make themselves appear larger, and may strike and bite. If grabbed, these snakes writhe and release a foul-smelling secretion; they will also urinate on their attacker.

Known Predators:

  • hawks (Accipitridae)
  • American crows (Corvus brachyrhynchos)
  • raccoons (Procyon lotor)
  • shrews (Soricidae)
  • milk snakes and king snakes (Lampropeltis)
  • coral snakes (Elapidae)
  • large fish (Actinopterygii)
  • bullfrogs (Lithobates catesbeianus)
  • snapping turtles (Chelydridae)
  • great blue herons (Ardea herodias)
  • foxes (Canidae)
  • squirrels (Sciuridae)

Anti-predator Adaptations: cryptic

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Zimmerman, R. 2002. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Thamnophis_sirtalis.html
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Common garter snake

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The common garter snake (Thamnophis sirtalis) is a species of natricine snake, which is indigenous to North America and found widely across the continent. Most common garter snakes have a pattern of yellow stripes on a black, brown or green background, and their average total length (including tail) is about 55 cm (22 in), with a maximum total length of about 137 cm (54 in).[2][3] The average body mass is 150 g (5.3 oz).[4] Common garter snakes are also the state reptile of Massachusetts.[5]

Subspecies

Current scientific classification recognizes 13 subspecies (ordered by date):[6]

Nota bene: A trinomial authority in parentheses indicates that the subspecies was originally described in a genus other than Thamnophis.

Etymology

The subspecific name, fiestchi, is in honor of American herpetologist Henry Sheldon Fitch.[7]

The subspecific name, lowei, is in honor of American herpetologist Charles Herbert Lowe.[8]

The subspecific name, pickeringii, is in honor of American naturalist Charles E. Pickering.[9]

Description

Common garter snakes are thin snakes. Few grow over about 4 ft (1.2 m) long, and most stay smaller. Most have longitudinal stripes in many different colors. Common garter snakes come in a wide range of colors, including green, blue, yellow, gold, red, orange, brown, and black.

Life history

The common garter snake is a diurnal snake. In summer, it is most active in the morning and late afternoon; in cooler seasons or climates, it restricts its activity to the warm afternoons.

In warmer southern areas, the snake is active year-round; otherwise, it sleeps in common dens, sometimes in great numbers. On warm winter afternoons, some snakes have been observed emerging from their hibernacula to bask in the sun.

Venom

 src=
Tetrodotoxin effects in garter snakes

The saliva of a common garter snake may be toxic to amphibians and other small animals. Garter snakes have a mild venom in their saliva.[10] For humans, a bite is not dangerous, though it may cause slight itching, burning, and/or swelling. Most common garter snakes also secrete a foul-smelling fluid from postanal glands when handled or harmed.

Common garter snakes are resistant to naturally found poisons such as that of the American toad and rough-skinned newt, the latter of which can kill a human if ingested. They have the ability to absorb the toxin from the newts into their bodies, making them poisonous, which can deter potential predators.[11]

The common garter snake uses toxicity for both offense and defense. On the offensive side, the snake's venom can be toxic to some of its smaller prey, such as mice and other rodents.[11] On the defensive side, the snake uses its resistance to toxicity to provide an important antipredator capability.[12] A study on the evolutionary development of resistance of tetrodotoxin tested between two populations of Thamnophis and then tested inside a population of T. sirtalis. Those that were exposed to and lived in the same environment as the newts (Taricha granulosa) that produce tetrodotoxin when eaten were more immune to the toxin (see figure).[12]

While resistance to tetrodotoxin is beneficial in acquiring newt prey, costs are associated with it, as well. Consuming the toxin can lead to reduced speed and sometimes no movement for extended periods of time, along with impaired thermoregulation.[13] The antipredator display that this species uses demonstrates the idea of an "arms race" between different species and their antipredator displays.[12] Along the entire geographical interaction of T. granulosa and T. sirtalis, patches occur that correspond to strong coevolution, as well as weak or absent coevolution. Populations of T. sirtalis that do not live in areas that contain T. granulosa contain the lowest levels of tetrodotoxin resistance, while those that do live in the same area have the highest levels of tetrodotoxin resistance. In populations where tetrodotoxin is absent in T. granulosa, resistance in T. sirtalis is selected against because the mutation causes lower average population fitness. This helps maintain polymorphism within garter snake populations.[14]

Reproduction

In the early part of spring, when snakes are coming out of hibernation, the males generally emerge first to be ready when the females wake up. Some males assume the role of a female and lead other males away from the burrow, luring them with a fake female pheromone.[15] After such a male has led rivals away, he "turns" back into a male and races back to the den, just as the females emerge. He is then the first to mate with all the females he can catch. This method also serves to help warm males by tricking other males into surrounding and heating up the male, and is particularly useful to subspecies in colder climates (such as T. s. parietalis).[16] Generally, populations include far more males than females, so during mating season, they form "mating balls", where one or two females are completely swamped by 10 or more males. Sometimes, a male snake mates with a female before hibernation, and the female stores the sperm internally until spring, when she allows her eggs to be fertilized. If she mates again in the spring, the fall sperm degenerate, and the spring sperm fertilize her eggs. The females may give birth ovoviviparously to 12 to 40 young from July through October.

Habitat

The habitat of the common garter snake ranges from forests, fields, and prairies to streams, wetlands, meadows, marshes, and ponds, and it is often found near water. It is found at altitudes from sea level to mountain locations. Depending on the subspecies, the common garter snake can be found as far south the southern-most tip of Florida in the U.S and as far north as the southern-most tip of the Northwest Territories in Canada.

Diet

The diet of T. sirtalis consists mainly of amphibians and earthworms, but also fish, small birds, and rodents. Common garter snakes are effective at catching fast-moving creatures such as fish and tadpoles.

As prey

Animals that eat the common garter snake include large fish (such as bass and catfish), bullfrogs, snapping turtles, larger snakes, hawks, raccoons, foxes, wild turkeys, and domestic cats and dogs.

Conservation

Water contamination, urban expansion, and residential and industrial development are all threats to the common garter snake. The San Francisco garter snake (T. s. tetrataenia), which is extremely scarce and occurs only in the vicinity of ponds and reservoirs in San Mateo County, California, has been listed as an endangered species by the U.S. Fish and Wildlife Service since 1967.

Antipredatory displays

Garter snakes exhibit many different antipredatory behaviors, or behaviors that ward off predators. Morphology refers to the shape that the snake's body makes in response to the environment, predatory defense, mating, etc. The term body geometry may also be used to describe the shape a snake's body makes. Garter snakes exhibit a higher variation of morphology when compared to other snakes. Predation has been such an intense selection pressure throughout evolution, these snakes have developed body geometries that are highly variable and heritable. These morphologies have been concluded to be highly variable even within a single population.[17] Different geometries indicate whether the snake is preparing to flee, fight, or protect itself. Since the traits are heritable, some evolutionary benefit must exist, such as warding off predators. Different biological factors such as body temperature and sex also influence whether the snake exhibits certain antipredatory behaviors.[18]

Studies show that the warmer the temperature of a garter snake, the more likely the snake is to flee a predator; a snake with a cooler body temperature remains stationary or attacks. However this is not always true. Male garter snakes are also more likely to flee.[18][19] Garter snakes that exhibit more aggressive antipredatory displays tend to also be fast and have high stamina. However, the cause for correlation is unknown.[20]

 src=
Effects of temperature in the common garter snake

As said, temperature can play a part in the antipredator behavior of the common garter snake.[18] Temperature can also be the factor that determines whether the snake stays passive or attacks when provoked by a predator. For example, one study found that snakes are less likely to escalate in response to an attack when the temperature is lower. One study tested the activity of the snake in response to different temperatures while being provoked by touching or by almost touching. By recording the popular responses as passive or aggressive, the study concluded that as temperature goes down, so does the antipredator response and general activity of the snake. Thus, temperature is important in determining the snake's antipredatory responses.[19]

The same study included the idea that the first response of the snake is actually a bluff. When the snake was teased with a finger, the snake reacted aggressively, but once touched, it became passive and did not react with any more violence.[19] This is most likely because the snake will not attack an organism it sees as larger than itself. This behaviour was seen multiple times throughout the course of the experiment. Aposematism, or warning coloration, is another factor that influences antipredator behavior. For example, the coral snake exhibits aposematic coloration that can be mimicked.[21] While garter snakes do not exhibit mimicry or aposematic coloration, these snakes will freeze until they know they are spotted, then slowly and successively slither away, while spotted and unstriped snakes are more likely to deceptively flee from predators.[22]

The decision of a juvenile garter snake to attack a predator can be affected by whether the snake has just eaten or not. Snakes that have just eaten are more likely to strike a predator or stimulus than snakes that do not have a full stomach. Snakes are more likely to flee a threatening situation if their stomachs are empty. Snakes that have just eaten a large animal are less mobile. Feeding positively affects endurance as opposed to speed.[23]

Another factor that controls the antipredatory response of the garter snake is where, on its body, the snake is attacked. Many birds and mammals prefer to attack the head of the snake. A research study found that garter snakes are more likely to hide their heads and move their tails back and forth when being attacked close to the head. The same study concluded that snakes that were attacked in the middle of their bodies were more likely to flee or exhibit open-mouthed warning reactions.[24]

Time may be another factor that contributes to antipredatory responses. Garter snakes are affected by maturation time. As snakes mature, the length of time at which garter snakes can display physical activity at 25 °C increases. Juvenile snakes can only be physically active for 3-5 minutes. Adult snakes can be physically active up to 25 minutes. This is mostly due to aerobic energy production; pulmonary aeration increases up to three times in adult garter snakes when compared to juveniles. The quick fatigue of the juveniles most certainly limits the habitats they can live in, as well as their food sources.[25] It absolutely affects the antipredator response of both juvenile and adult garter snakes; without sufficient energy production, the snake cannot exhibit any antipredatory response.

Female garter snakes produce a specific pheromone. Some males of various species of garter snakes exhibit female behavior and morphology. This type of mimicry is primarily found in the red-sided garter snake. A portion of the males that exhibit female mimicry also secrete the sex-specific hormone to attract other males. In a study these "she-males" mated with females significantly more often than males that did not exhibit this mimicry.[26] A male pretending to be a female around other males increases his chances of reproduction and protects against stronger, more aggressive males.

See also

References

  1. ^ Frost DR, Hammerson GA, Santos-Barrera G (2015). Thamnophis sirtalis. The IUCN Red List of Threatened Species 2015 doi:10.2305/IUCN.UK.2015-2.RLTS.T62240A68308267.en
  2. ^ Conant, Roger. (1975). A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition. Boston: Houghton Mifflin. ISBN 0-395-19979-4. (Thamnophis sirtalis, pp. 157–160 + Plates 23 & 24 + Map 116).
  3. ^ Eastern Garter Snake (Thamnophis sirtalis). uga.edu
  4. ^ Fast Facts: Common garter snake. Canadian Geographic
  5. ^ "Citizen Information Service: State Symbols". Massachusetts State (Secretary of the Commonwealth). Retrieved 2011-01-21. The Garter Snake became the official reptile of the Commonwealth on January 3, 2007.
  6. ^ Thamnophis sirtalis , Reptile Database
  7. ^ Boelens et al., p. 90.
  8. ^ Beolens et al., p. 161.
  9. ^ Beolens et al., p. 207.
  10. ^ "Two things you probably didn't know about garter snakes". Living digitally. 5 May 2016. Retrieved 5 May 2016.
  11. ^ a b Williams BL, Brodie ED Jr, Brodie ED III (2004). "A resistant predator and its toxic prey: Persistence of newt toxin leads to poisonous (not venomous) snakes". J Chem Ecol. 30 (10): 1901–19. doi:10.1023/b:joec.0000045585.77875.09. PMID 15609827.
  12. ^ a b c Brodie ED III, Brodie ED Jr (1990). "Tetrodotoxin resistance in garter snakes: an evolutionary response of predators to dangerous prey". Evolution. 44 (3): 651–59. doi:10.2307/2409442. JSTOR 2409442.
  13. ^ Williams, Becky L.; Brodie Jr., Edmund D.; Brodie III, Edmund D. (2003). "Coevolution of deadly toxins and predator resistance: self-assessment of resistance by garter snakes leads to behavioral rejection of toxic newt prey" (PDF). Herpetologica. 59: 155–163. doi:10.1655/0018-0831(2003)059[0155:codtap]2.0.co;2.
  14. ^ Brodie Jr., Edmund D.; Ridenhour, B. J.; Brodie III, E. D. (2002). "The evolutionary response of predators to dangerous prey: hotspots and coldspots in the geographic mosaic of coevolution between garter snakes and newts". Evolution. 56 (10): 2067–2082. doi:10.1554/0014-3820(2002)056[2067:teropt]2.0.co;2. PMID 12449493.
  15. ^ Crews, David; Garstka, William R. (1982). "The Ecological Physiology of a Garter Snake". Scientific American. 247: 159–168. doi:10.1038/scientificamerican1182-158.
  16. ^ Mason, Robert T.; Crews, David (1985). "Female Mimicry in Garter Snakes" (PDF). Nature. 316 (6023): 59–60. doi:10.1038/316059a0. PMID 4010782.
  17. ^ Garland, T. (1988). "Genetic Basis of Activity Metabolism. I. Inheritance of Speed, Stamina & Antipredator Display in the Garter Snake, Thamnophis sirtalis" (PDF). Evolution. 42 (2): 335–350. doi:10.2307/2409237.
  18. ^ a b c Shine, R.; M.M. Olsson; M.P. Lesmaster; I.T. Moore & R.T. Mason (1999). "Effects of Sex, Body, Size, Temperature & Location on the Antipredator Tactics of Free-Ranging Garter Snakes (Thamnophis sirtalis, Colubridae)". Oxford Journal. 11 (3): 239–245. doi:10.1093/beheco/11.3.239.
  19. ^ a b c Schieffelin, C. D.; de Queiroz, A. (1991). "Temperature and defense in the common garter snake: warm snakes are more aggressive than cold snakes". Herpetologica. 47: 230–237. JSTOR 3892738.
  20. ^ Brodie III, E.D. (1992). "Correlational Selection For Color Pattern & Antipredator Behavior In The Garter Snake". Evolution. 46 (5): 1284–1298. doi:10.2307/2409937. JSTOR 2409937.
  21. ^ Greene, H.W.; McDiarmid, R.W. (1981). "Coral Snake Mimicry: Does It Occur?". Science. 213 (4513): 1207–1212. doi:10.1126/science.213.4513.1207. PMID 17744739.
  22. ^ Arnold, S.J.; Bennett, A.F. (1984). "Behavioural Variation in Natural Population III: Antipredator Display in the Garter Snake Thamnophis radix" (PDF). Animal Behaviour. 32 (4): 1108–1118. doi:10.1016/S0003-3472(84)80227-4.
  23. ^ Herzog, Harold A. Jr.; Bailey, Bonnie D. (1987). "Development of Antipredator Responses in Snakes: II. Effects of recent feeding on defensive behaviors of juvenile garter snakes (Thamnophis sirtalis)". Journal of Comparative Psychology. 101 (4): 387–389. doi:10.1037/0735-7036.101.4.387.
  24. ^ Langkilde, Tracy; Shine, Richard; Mason, Robert T. (2004). "Predatory Attacks to the Head vs. Body Modify Behavioral Responses of Garter Snakes". Ethology. 110 (12): 937–947. doi:10.1111/j.1439-0310.2004.01034.x.
  25. ^ Pough, F. Harvey (1977). "Ontogenetic Change in Blood Oxygen Capacity and Maximum Activity in Garter Snakes (Thamnophis sirtalis)". Journal of Comparative Physiology. 116 (3): 337–345. doi:10.1007/BF00689041.
  26. ^ Mason, Robert T.; Crews, David (1985). "Female Mimicry in Garter Snakes". Nature. 316 (6023): 59–60. doi:10.1038/316059a0. PMID 4010782.
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Common garter snake: Brief Summary

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The common garter snake (Thamnophis sirtalis) is a species of natricine snake, which is indigenous to North America and found widely across the continent. Most common garter snakes have a pattern of yellow stripes on a black, brown or green background, and their average total length (including tail) is about 55 cm (22 in), with a maximum total length of about 137 cm (54 in). The average body mass is 150 g (5.3 oz). Common garter snakes are also the state reptile of Massachusetts.

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