| Western terrestrial garter snake | |
|---|---|
 | |
| T. elegans terrestris | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Suborder: | Serpentes |
| Family: | Colubridae |
| Genus: | Thamnophis |
| Species: | T. elegans |
| Binomial name | |
| Thamnophis elegans | |
| 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.
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 with its 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]
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]
Six subspecies have been identified, although the validity of some of them is debated. [2]
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]
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. [10]
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. [11] There are two main variants that are most prevalent: coastal and inland. [12] 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. [13] 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. [12] 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. [12] Further, this appears to be genetically determined as this variation in diet is observed in newborn snakes from both populations. [11] When hunting, the Western Garter Snake's actions are chemically and visually mediated on land and in water. [13] Regardless the habitat in which foraging takes place, both ecotypes utilize similar techniques. This consists of attacks that are both aerial and underwater. [12] These include craning, cruising, and diving. However, coastal snakes are less likely to participate these activities. [12]
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. [12]
Garter snake is the common name for small to medium-sized snakes belonging to the genus Thamnophis in the family Colubridae. They are native to North and Central America, ranging from central Canada in the north to Costa Rica in the south.
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.
Diadophis punctatus, commonly known as the ring-necked snake or ringneck snake, is a rather small, harmless species of colubrid snake found throughout much of the United States, as well as south in Central Mexico and as far north as Quebec, Canada. Ring-necked snakes are generally fossorial and somewhat secretive, by nature, and, as a nocturnal species, are rarely seen during the daytime. These snakes are believed to be fairly abundant throughout most of their range, though no scientific evaluation supports this hypothesis. Scientific research is lacking for the species, despite their apparently common status, and more in-depth investigations are greatly needed. It is the only species within the genus Diadophis and, currently, 14 subspecies are identified, though many herpetologists question the morphologically-based classifications.
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.
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.
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The eastern garter snake is a medium-sized snake indigenous to North America.
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.
The two-striped garter snake is a species of aquatic snake in the subfamily Natricinae of the family Colubridae. The species is endemic to western North America.
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