Thamnophis proximus

Geographic Range

Thamnophis proximus , the Western ribbon snake , can be found ranging from the United States specifically Wisconsin and southward, down into Central America, including Belize and Costa Rica. The species is usually found active during early spring into the summer, and is most active during the day or during warm periods. In areas with changeable seasons, the Western Ribbon Snake will hibernate in rocky outcroppings, sometimes with other species.

This species is found in more brush-heavy habitats, close to water sources. They can also be found basking on rocks or flat vegetation, or in sandy, drier areas that are also close to water. Due to it's slender body, it is believed that this and other garter snake species evolved to adapt to more forest-heavy habitats.

• Biogeographic Regions
• neotropical neotropical
  • native native
• atlantic ocean atlantic ocean
  • native native
• pacific ocean pacific ocean
  • native native

• Other Geographic Terms
• cosmopolitan cosmopolitan

Habitat

This species can be found in a wide range of habitats, usually around brush-heavy areas with bodies of water like streams, ponds, lakes, etc. It is a semi-aquatic species, and generally does not live far away from a water source (Sunyer et al., 2013). They will dive into water if disturbed, or hide themselves in thick brush or within crevices. Their body coloration helps them hide in these areas. They prefer warmer temperatures, but can be active between 4 and 42 degrees Celsius, with 22-26 their preference.

• Habitat Regions
• temperate temperate
• tropical tropical
• terrestrial terrestrial
• freshwater freshwater

• Terrestrial Biomes
• forest forest
• rainforest rainforest

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• temporary pools
• coastal coastal
• brackish water brackish water

• Wetlands
• marsh marsh
• swamp swamp
• bog bog

• Other Habitat Features
• estuarine estuarine

Physical Description

The Western Ribbon Snake is often confused with the Eastern Ribbon Snake , which has a very similar look and coloration. A few distinguishing characteristics include the reduction or absence of a broad, brown ventro-lateral stripe found on the Eastern species. The large paired parietal spots, longer muzzle and tail on the Western Ribbon Snake are also a distinguishing features. They have pale undersides, usually a light yellow or green, while their backs will typically be dark brown or black with lighter side stripes. The Western Ribbon Snake have a maximum recorded SVL (snout to vent length) of 1250 mm (around 50 inches). Most remain around 3 feet. Their tail is roughly 30% of their body length.

Juveniles tend to be smaller than adults in body, but with proportionally larger heads. T

Like other garter snakes, this species of snake is non-venomous, and not lethal to humans.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

Development

Thamnophis proximus births live young, which are relatively small compared to adults (around 20 cm). Their tail-to-body ratio, however, is fairly large, and their tails also experience rapid and disproportionate growth. Juveniles are still small compared to adults, but their head size is proportionally larger, giving them an advantage when it comes to catching and consuming larger prey. Adults do not retain this head to body proportion.

Reproduction

Thamnophis proximus is most reproductively active during the spring, but the exact season in which breeding occurs is unknown. Males will trail females by following their scent in order to copulate. Because their sense of smell is so developed, they can follow for some distance.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Female western ribbon snakes can be gravid as early as April, but births usually occur between June and mid-September. Females incubate the eggs within and then have live births of between 3 and 21 offspring. The offspring's mean length can be 16 to 28cm, with little variation within clutches. Mass size varies greater within clutches, from 1.1 to 3.1 grams. Larger females tend to give birth to larger clutches with greater mass.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• sexual sexual
• viviparous viviparous
• ovoviviparous ovoviviparous

• Parental Investment
• female parental care female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Behavior

This species has adapted a special technique of foraging for amphibians, specifically frogs. Thamnophis proximus will move over land and make light thrusts with it's head and upper body, similar to a strike, but with a closed mouth. These thrusts are in sequences of three, each in quick succession and in different directions. A frog will be disturbed by these thrusts, and alert the snake to its location. The snake can then give chase. Thamnophis proximus is fast, and uses this speed for both capturing quick prey like frogs or fish, and for escaping potentially dangerous situations. If disturbed, Thamnophis proximus will disappear into nearby brush or crevices, or even dive into water and swim away if there is a body of water in close proximity. During warm seasons they are active during the day, hunting for food or laying in the sun. In areas with cold seasons, these snakes will hibernate in caves and crevices until a armer period returns. They have been seen emerging while it is still winter, after a few consecutive days of warmth.

• Key Behaviors
• terricolous
• natatorial natatorial
• diurnal diurnal
• motile motile
• hibernation hibernation

Communication and Perception

This species hunts visually, using its head to startle prey into view and give chase. In general, Thamnophis proximus communicates using its forked tongue, which can collect chemicals from the air that the snake will interpret. This is especially useful when following the trail of a female, looking for a potential mate. They will also use touch as a communication method. Thamnophis proximus can also sense vibrations, which can tell them if a prey species is nearby, or a possible predator.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• scent marks scent marks
• vibrations vibrations

• Perception Channels
• visual visual
• tactile tactile
• vibrations vibrations
• chemical chemical

Food Habits

The main food for Thamnophis proximus are amphibians, with studies reporting them to be between 80-92% of their diet. Besides amphibians, Thamnophis proximus will consume fish, snails, eggs that they find, crustaceans, and rarely small mammals. Thamnophis proximus varies its diet based on its individual size. Larger than average snakes will catch larger prey, while smaller snakes with smaller mouths and body capacities will eat smaller prey. With this variation in prey size comes a variation in consumption times - after eating larger prey, a snake will have a longer period between meals in order to digest. Juvenile snakes with a relatively smaller body size compared to adults often have a proportionally-larger head in order to increase their gape, and the size of prey available. Adult snakes will eat smaller prey, as the head-to-body proportion does not continue into adulthood, and has not been shown to be advantageous.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • piscivore piscivore
  • eats eggs
  • eats non-insect arthropods
  • molluscivore molluscivore
  • vermivore
  • eats other marine invertebrates

• Animal Foods
• amphibians
• reptiles
• fish
• eggs
• mollusks
• terrestrial worms
• aquatic crustaceans

Predation

Eaten by various predatory birds and mammals - Weasels, ferrets, large fish, predatory birds (hawks, eagles) and raptors,and other large snakes like rattlesnakes or cottonmouth snakes. When captured by a human or a predator, this snake will thrash its body around to try and escape, usually emitting a foul smell or spraying feces to encourage the foe to release it. The western ribbon snake can also shed its tail, which will continue to move in order to allow the snake to escape. The tail will not regenerate.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

The western ribbon snake has a diet that consists of mostly amphibians, which controls amphibious populations, but has the potential to decimate those populations in certain areas.

Economic Importance for Humans: Positive

Thamnophis proximus eats pests and helps control prey populations that can be pests, including insects and amphibians.

• Positive Impacts
• controls pest population

Economic Importance for Humans: Negative

No known negative impacts on humans.

Conservation Status

This species is listed as least concern and special status on the IUCN Red List, the US Federal List, Cites.org, and the State of Michigan list. It is listed as endangered by the Wisconsin DNR.

This species is very much affected by human development and disturbances in their habitat. Water drainage sites drain water sources for them. Roads and highways offer dangerous blockages for their populations. Climate change is also affecting both the western ribbon snake and its prey - amphibians. Drier seasons lead to water shortages, and therefore limit snake habitats and amphibian hibernation sites.

Pesticides, road substrates and road chemicals have a negative affect on snake health, as well as affecting their pheromone emittance.

Other Comments

There are 6 subspecies of Thamnophis proximus : T. p. alpinus (high-elevation), T. p. diabolicus (Colorado and southward through Pecos Valley), T. p. orarius (Coastal Louisiana to Northeastern Tamaulipas), T. p. rubrilineatus (Central Texas plateaus), and T. p. rutiloris (southern Tamaulipas to central Costa Rica).

Additional Links

Encyclopedia of Life

Contributors

Margaret Waters (author), Minnesota State University Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

Clark Jr., C. 1974. The Western Ribbon Snake (Thamnophis proximus): Ecology of a Texas Population. Herpetologica , 30 No. 4: 372-379.

Dewey, T. 2005. "Thamnophis sauritus - Eastern Ribbonsnake" (On-line). Animal Diversity Web. Accessed April 05, 2017 at http://animaldiversity.org/accounts/Thamnophis_sauritus/ .

Ford, N. 1981. Seasonality of Pheromone Trailing Behavior in Two Species of Garter Snake, Thamnophis (Colubridae). The Southwestern Naturalist , 26/4: 385-388.

Hampton, P. 2011. Feeding performance in the Western Ribbon Snake (Thamnophis proximus): ontogeny and the effects of prey type and size. Canadian Journal of Zoology , 89: 945.

Hampton, P. 2008. Prey Items of the Western Ribbon Snake, Thamnophis proximus. The Southwestern Naturalist , 53: 115-118.

Lancaster, D., N. Ford. 2003. Reproduction in western ribbon snakes, Thamnophis proximus (Serpentes: Colubridae), from an east Texas bottomland. The Texas Journal of Science , 55: 25.

Penn State New Kingston, 2002. "The Virtual Nature Trail at Penn State New Kingston" (On-line). The Virtual Nature Trail at Penn State New Kingston. Accessed April 19, 2017 at http://www.psu.edu/dept/nkbiology/naturetrail/speciespages/ribbonsnake.htm .

Rossman, D., N. Ford, R. Seigel. 1996. The Garter Snakes: Evolution and Ecology . University of Oklahoma Press, Norman.: University of Oklahoma Press.

Rossman, D. 1962. Thamnophis proximus (Say), a Valid Species of Garter Snake. Copeia , 1962 No. 4: 741-748.

Sunyer, J., G. Chaves, W. Lamar, L. Porras, A. Solórzano, G. Hammerson. 2013. "Thamnophis proximus" (On-line). The IUCN Red List of Threatened SpeciesThe IUCN Red List of Threatened Species. Accessed February 14, 2017 at http://dx.doi.org/10.2305/IUCN.UK.2013- .

Wendelken, P. 1978. On Prey-Specific Hunting Behavior in the Western Ribbon Snake, Thamnophis Proximus (Reptilia, Serpentes, Colubridae). Journal of Herpetology , 12/4: 577-578. Accessed April 05, 2017 at www.jstor.org/stable/1563367. .

Wisconsin Department of Natural Resources, 2013. "Western Ribbonsnake Species Guidance" (On-line). Wisconsin Department of Natural Resources. Accessed April 19, 2017 at http://dnr.wi.gov/files/PDF/pubs/er/ER0712.pdf .

2011. "Western ribbon snake fact file" (On-line). Widescreen Archive. Accessed February 14, 2017 at http://www.arkive.org/western-ribbon-snake/thamnophis-proximus/ .