Western terrestrial garter snake

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Western terrestrial garter snake
Coast Garter Snake.jpg
T. elegans terrestris
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Colubridae
Genus: Thamnophis
Species:
T. elegans
Binomial name
Thamnophis elegans
(Baird & Girard, 1853) [2]
Subspecies

6 sspp., see text

Synonyms

The western terrestrial garter snake (Thamnophis elegans) is a western North American species of colubrid snake. At least five subspecies are recognized.

Contents

Description

Most western terrestrial garter snakes have a yellow, light orange, or white dorsal stripe, accompanied by two stripes of the same color, one on each side. Some varieties have red or black spots between the dorsal stripe and the side stripes. It is an immensely variable species, and even the most experienced herpetologists have trouble when it comes to identification. They are medium-sized snakes, usually 46–104 cm (18–41 in).

Like many species of North American garter snake, the western terrestrial garter snake possesses a mildly venomous saliva. Specimens collected from Idaho and Washington produced venom with myonecrotic (muscle tissue-killing) effects when injected into the gastrocnemius muscles of mice. [3] Several cases of mild human envenomation with local edema and other symptoms (but without any systemic symptoms) have occurred from the wandering garter snake subspecies, including in Colorado. [4] [5]

This species is the only garter snake species with a well-documented tendency to constrict prey, although the constriction is inefficient when compared with the constriction of many other snakes (such as the gopher snake), involving disorganized, loose, and sometimes unstable coils and a longer time required to kill prey. [6] [7] Snakes from Colorado populations of terrestrial garter snakes appear to be more efficient at killing their prey by constriction than those from Pacific Coast populations. [6]

Geographic range

Thamnophis elegans is found in central British Columbia, central Alberta, and southwestern Manitoba in Canada. [1] It can be found in the western United States, as far east as western Nebraska and the Oklahoma Panhandle. An isolated population occurs in Baja California, Mexico. [8]

Subspecies

Thamnophis elegans terrestris with dark coloring Big Sur Snake.JPG
Thamnophis elegans terrestris with dark coloring

Six subspecies have been identified, although the validity of some of them is debated. [2]

Habitat

Thamnophis elegans occurs in a wide variety of habitats, including grasslands, woodlands, and coniferous forests, from sea level up to 3,962 m (12,999 ft). It is primarily terrestrial, although populations in the Great Basin and Rocky Mountains are semi-aquatic. [8]

Reproduction

The western terrestrial garter snake does not lay eggs, but instead is ovoviviparous, which is characteristic of natricine snakes. Broods of eight to 12 young are born in August and September. [9]

Diet

The diet of Thamnophis elegans depends heavily on the prey available in the local area, and thus varies due to regional geographical differences. This makes the western terrestrial garter snake an excellent example of polyphagism—the adaptation of an organism to maintain a varied diet. [10] There are two main variants that are most prevalent: coastal and inland. [11] As T. elegans is found along the Pacific West Coast of the United States, they will often be seen hunting at or adjacent-to beaches, estuaries, lagoons and marshes along the coast, often at sites where ocean saltwater meets an inland freshwater source (brackish water). Meanwhile, more inland or montane populations are often found adjacent to fresh water sources such as creeks, rivers, streams, ponds, or lakes.

Coastal populations' food sources mainly include terrestrial prey such as earthworms, grubs, caterpillars, crickets, small snails, slugs, salamanders, baby rodents (such as small ground squirrels and other mammals) and small lizards or toads. By comparison, inland and montane populations prefer a far more “amphibious” diet of small frogs, newts, salamanders, toads and their larvae, as well as freshwater leeches, earthworms and small fish. [12] Thus, aquatic food sources are a staple in the inland snake populations' diet.

Coastal snakes are less likely to respond to chemical cues received from fish, which can be inferred by less rapid tongue-flicking when around them. [11] They are also less likely to attack and ingest fish. This preference in diet is so strong that the snake will starve before eating non-preferred prey types. [11] Further, this appears to be genetically determined as this variation in diet is observed in newborn snakes from both populations. [10] When hunting, the Western Garter Snake's actions are chemically and visually mediated on land and in water. [12] Regardless the habitat in which foraging takes place, both ecotypes utilize similar techniques. This consists of attacks that are both aerial and underwater. [11] These include craning, cruising, and diving. However, coastal snakes are less likely to participate these activities. [11]

These differences in diet and foraging behavior between coastal and inland snake populations suggest that the species has undergone microevolution. Due to dietary and foraging differences between variants of T. elegans, it can be inferred that coastal populations have filled a niche in the environment that allows them to no longer rely on fish as a major food source. [11]

Related Research Articles

<span class="mw-page-title-main">Garter snake</span> Common name for North American snakes of the genus Thamnophis

Garter snake is the common name for small to medium-sized snakes belonging to the genus Thamnophis in the family Colubridae. Native to North and Central America, species in the genus Thamnophis can be found in all of the lower 48 United States, and nearly all of the Canadian provinces south of the Northwest Territories and Nunavut—with the exception of Newfoundland and Labrador. They are found from the subarctic plains of west-central Canada east through Ontario and Quebec; from the Maritime Provinces and south to Florida, across the southern and central U.S. into the arid regions of the southwest and Mexico, Guatemala and south to the neotropics and Costa Rica.

<span class="mw-page-title-main">Common garter snake</span> Species of snake

The common garter snake is a species of snake in the subfamily Natricinae of the family Colubridae. The species is indigenous to North America and found widely across the continent. There are several recognized subspecies. Most common garter snakes have a pattern of yellow stripes on a black, brown or green background, and their average total length 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). The common garter snake is the state reptile of Massachusetts.

Constriction is a method used by several snake species to kill or subdue their prey. Although some species of venomous and mildly venomous snakes do use constriction to subdue their prey, most snakes which use constriction lack venom. The snake strikes at its prey and holds on, pulling the prey into its coils or, in the case of very large prey, pulling itself onto the prey. The snake then wraps one or two loops around the prey, forming a constriction coil. The snake monitors the prey's heartbeat to ascertain it is dead. This can be a physically demanding and potentially dangerous procedure for the snake, because its metabolism is accelerated up to sevenfold and it becomes vulnerable to attack by another predator.

<span class="mw-page-title-main">California newt</span> Species of amphibian

The California newt or orange-bellied newt, is a species of newt endemic to California, in the Western United States. Its adult length can range from 5 to 8 in. Its skin produces the potent toxin tetrodotoxin.

<i>Thamnophis saurita</i> Species of snake

Thamnophis saurita, also known as the eastern ribbon snake, common ribbon snake, or simply ribbon snake, is a common species of garter snake native to Eastern North America. It is a non-venomous species of snake in the subfamily Natricinae of the family Colubridae. The ribbon snake averages 16 to 35 inches in total length. It is dark brown with bright yellow stripes. The ribbon snake is not sexually dimorphic; however, females are normally thicker than their male counterparts.

<span class="mw-page-title-main">San Francisco garter snake</span> Subspecies of snake

The San Francisco garter snake is a slender multi-colored subspecies of the common garter snake. Designated as an endangered subspecies since the year 1967, it is endemic to San Mateo County and the extreme northern part of coastal Santa Cruz County in California.

<span class="mw-page-title-main">Eastern garter snake</span> Subspecies of snake

The eastern garter snake is a medium-sized snake indigenous to North America.

<span class="mw-page-title-main">Giant garter snake</span> Species of snake

The giant garter snake is the largest species of garter snake. Relatively rare, it is a semi-aquatic snake with a limited distribution in the wetlands of central California.

<i>Thamnophis saurita saurita</i> Subspecies of snake

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<span class="mw-page-title-main">Sierra newt</span> Species of amphibian

The Sierra newt is a newt found west of the Sierra Nevada, from Shasta county to Tulare County, in California, Western North America.

<span class="mw-page-title-main">Aquatic garter snake</span> Species of snake

The aquatic garter snake is a species of colubrid snake. Three subspecies are currently recognized.

<span class="mw-page-title-main">Blackneck garter snake</span> Species of snake

Thamnophis cyrtopsis, the blackneck garter snake, is a species of garter snake of the genus Thamnophis. It is native to the southwestern United States, Mexico and Guatemala, and can be found in a wide range of different habitats, often near water sources.

Thamnophis sirtalis semifasciatus, the Chicago garter snake, is a subspecies of the common garter snake native to the Chicago, United States, region. It was described by Edward Drinker Cope in 1892, and can be found in the vicinity of rural waterways in northeastern Illinois, such as Piscasaw Creek in Boone County and McHenry County, Illinois.

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There are 14 species of amphibians and 5 species of reptiles known to occur in Mount Rainier National Park.

<span class="mw-page-title-main">Shorthead garter snake</span> Species of snake

Thamnophis brachystoma, commonly known as the shorthead garter snake or short-headed gartersnake, is a small species of colubrid snake. The species is endemic to the north-eastern United States.

<span class="mw-page-title-main">California red-sided garter snake</span> Subspecies of snake

The California red-sided garter snake is a subspecies of the common garter snake. This slender subspecies of natricine snake is indigenous to North America and is one of three recognized subspecies of Thamnophis sirtalis found in California. While commonly confused with the subspecies T. s. concinnus, it is biologically part of the population of the subspecies T. s. tetrataenia, as pointed out by Boundy and Rossman (1995), but was preserved as T. s. infernalis as a neotype under ICZN code Article 75 in a 2000 decision by the International Commission on Zoological Nomenclature (ICZN) in 2000 in order to preserve the existing subspecies taxonomy.

<span class="mw-page-title-main">Blackbelly garter snake</span> Species of snake

The blackbelly garter snake is a species of snake of the family Colubridae. It is found in Mexico.

<span class="mw-page-title-main">Mexican wandering garter snake</span> Species of snake

The Mexican wandering garter snake is a species of snake of the family Colubridae. It is endemic to Mexico.

References

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  2. 1 2 Thamnophis elegans at the Reptarium.cz Reptile Database. Accessed 12 December 2014.
  3. Jansen, David W (1987). "The Myonecrotic Effect of Duvernoy's Gland secretion of the snake Thamnophis elegans vagrans". Journal of Herpetology. 21 (1): 81–83. doi:10.2307/1564384. JSTOR   1564384.
  4. Gomez, H.F.; Davis, M.; Phillips, S.; McKinney, P.; Brent, J. (1984). "Human envenomation from a wandering garter snake". Annals of Emergency Medicine. 23 (5): 1119–22. doi:10.1016/s0196-0644(94)70113-x. PMID   8185110.
  5. Vest, DK (1981). "Envenomation following the bite of a wandering garter snake (Thamnophis elegans vagrans)". Clinical Toxicology. 18 (5): 573–9. doi:10.3109/15563658108990284. PMID   7273669.
  6. 1 2 de Queiroz, Alan; Groen, Rebecca R. (2001). "The inconsistent and inefficient constricting behavior of Colorado Western Terrestrial Garter Snakes, Thamnophis elegans". Journal of Herpetology. 35 (3): 450–460. doi:10.2307/1565963. JSTOR   1565963.
  7. Gregory, Patrick T.; Macartney, J. Malcolm; Rivard, Donald H. (1980). "Small mammal predation and prey handling behavior by the wandering garter snake Thamnophis elegans". Herpetologica. 36 (1): 87–93.
  8. 1 2 Stebbins, Robert C (2003). A field guide to western reptiles and amphibians (3rd ed.). Boston: Houghton Mifflin. pp. 377–380. ISBN   0395982723.
  9. Schmidt, K.P. and D.D. Davis. (1941). Field Book of Snakes of the United States and Canada. G.P. Putnam's Sons. New York. p. 246.
  10. 1 2 Arnold, Stevan J (August 12, 1977). "Polymorphism and Geographic Variation in the Feeding Behavior of the Garter Snake Thamnophis elegans". Science. 197 (4304): 676–678. Bibcode:1977Sci...197..676A. doi:10.1126/science.197.4304.676. PMID   17776270. S2CID   38341468.
  11. 1 2 3 4 5 6 Burghardt, Gordon M; Drummond, Hugh (1983). "Geographic Variation in the Foraging Behavior of the Garter Snake, Thamophis elegans". Behavioral Ecology and Sociobiology. 12 (1): 43–48. doi:10.1007/bf00296931. S2CID   34175574.
  12. 1 2 Whitaker, Jake. "Thamnophis elegans Western Terrestrial Garter Snake". Animal Diversity Web. University of Michigan Museum of Zoology. Retrieved October 23, 2014.