Hypsiglena torquata

Geographic Range

Night snakes are typically found from southern Mexico in the state of Guerrero (including Sinaloa, Nayarit, Jalisco, Colima, Michoacan, Guerrero, West Puebla, Morelos, and Aguascalientes) north through much of the western United States (northeastern Baja, California, Arizona, western Colorado, Utah, Nevada, eastern California, southern Idaho, Oregon and Washington) and into south central British Columbia, Canada. They have also been found in Texas, Kansas, and Oklahoma. Though widely distributed, night snakes are considered rare in many parts of their geographic range.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Night snakes are found in a variety of habitats (some more commonly than others), including rocky canyons (talus and scree), oak woodlands, savannahs, brushy flatlands, prairies, grasslands, croplands, and occasionally moist mountain meadows. They may be found hiding under surface debris or rocks and in crevices. Night snakes may be found from sea level up to 2650 meters above sea level and prefer arid or semi-arid habitats.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune
• savanna or grassland savanna or grassland
• chaparral chaparral
• forest forest
• scrub forest scrub forest
• mountains mountains

Physical Description

Night snakes are small, usually less than 66 centimeters in length. They have vertical pupils and bronze-copper colored eyes. Dorsal coloration consists of a tan ground color with darker brown saddle-shaped spots and lateral spots. The head is also dark brown, with the color stretching from the eyes to the base of the head where it forms a dark blotch, contrasting with the cream colored labial area. Ventral areas are pearly white (often iridescent). They are rear fanged and only mildly venomous. There is no seasonal variation in this species, but they do exhibit sexual dimorphism, with females up to three times longer than males. Night snakes are geographically widespread, with 17 sub-species currently recognized. Each may differ slightly in the above morphological characters and original type description, particularly with regards to patterns of nuchal color blotches, dorsal spots, and scale counts.

• Other Physical Features
• venomous venomous

• Sexual Dimorphism
• female larger

Development

Little is known about the development of night snake specifically, but it is likely that they follow the development pattern of other small snake species. After fertilization, females lay a clutch of 2-6 eggs, often in sandy soil. Young develop inside the egg, nourished by yolk, for 50-60 days, depending on temperature. When they hatch, young are independent and resemble small adults.

• Development - Life Cycle
• indeterminate growth indeterminate growth

Reproduction

There is no information currently available regarding specific mating behaviors of night snakes. However, it is possible that males compete for mates, as seen in a related species, Imantodes cenchoa . It is likely that females produce only one clutch of eggs in a breeding season and therefore that this species is polygnous, or possibly monogamous.

• Mating System
• polygynous polygynous

These snakes are capable of breeding from spring through early fall (April-September). Clutch size may range from 2-6 eggs (averaging 3) and there is no evidence that females produce more than one clutch of eggs in a breeding season. The smallest sexually mature male recorded measured about 237 millimeters SVL (snout-vent length), while the smallest sexually mature female recorded measured 310 mm SVL, suggesting that males reach sexual maturity earlier than females. Age at sexual maturity also likely varies depending on geographic location. Young are independent upon hatching.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• sexual sexual
• fertilization fertilization
• oviparous oviparous

This species is not known to exhibit any parental investment after eggs are laid.

• Parental Investment
• no parental involvement

Lifespan/Longevity

There is no data regarding the lifespan of night snakes in the wild, but they have been known to survive over 12 years in captivity.

Behavior

Night snake are crepuscular and nocturnal, and are found in burrows or rocky crevices during the day. They are solitary animals outside of breeding, though any particular area may have multiple night snakes as residents.

• Key Behaviors
• terricolous
• nocturnal nocturnal
• crepuscular crepuscular
• sedentary sedentary
• daily torpor
• solitary solitary

Home Range

There is no evidence that night snakes have specified home ranges or defend territories.

Communication and Perception

Night snakes have cat-like eyes with vertical pupils and larger cornea and lens apertures than diurnal snakes. Snakes mainly use their olfactory and vomeronasal systems to sense their environments. They use their forked tongues to draw air into pits in the roofs of their mouths, where neuroreceptors detect chemicals and other elements of their environments. They have well-developed senses of hearing, picking up sounds as vibrations along their bodies. They also have highly developed tactile receptors.

• Communication Channels
• tactile tactile
• chemical chemical

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

Food Habits

Night snakes use mild venom to subdue small prey. They are nocturnal hunters and prey items include scorpions, lizards ( Bipes biporus , Cnemidophorus tigris , Coleonyx variegatus , Dipsosaurus dorsalis , Elgaria multicarinata , Sceloporus graciosus , Uta stansburiana , Xantusia vigilis ) and their eggs (particularly of Uta stansburiana ), salamanders ( Batrachoseps sp.), frogs ( Pseudacris sp.), toads ( Bufo alvarius , Scaphiopus couchii , Spea hammondii ), other snakes ( Crotalus viridis ), and insects. They are also known to occasionally eat carrion and may eat animals that wander into their daytime hiding places.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • eats eggs
  • insectivore insectivore

• Animal Foods
• amphibians
• reptiles
• eggs
• carrion carrion
• insects
• terrestrial non-insect arthropods

Predation

These snakes hide during the day, avoiding predation by many species. Night snakes are likely preyed upon by owls, noctural mammals, and other snakes. They are a known prey item of red-tailed hawks.

Ecosystem Roles

Night snakes prey on multiple small vertebrate and invertebrate species, helping to control the populations of these animals. They also serve as prey to other vertebrate species such as birds and reptiles.

Economic Importance for Humans: Positive

Night snakes are nocturnal and live in areas mostly uninhabited by humans; there is no known positive economic importance for humans outside of scientific research, where studies have been conducted to test venom concentration as well as to analyze the systematics of the Hypsiglena torquata species complex.

• Positive Impacts
• research and education

Economic Importance for Humans: Negative

Texas night snakes ( Hypsiglena torquata texana ), a subspecies of night snake, has venom known to cause pain and possible hemorrhage in humans.

• Negative Impacts
• injures humans
  • bites or stings
  • venomous venomous

Conservation Status

Night snakes are classified as a species of "Least Concern" by the International Union for Conservation of Nature and Natural Resources due to their wide distribution and stable population size.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

Samuel Burrell (author), Hobart & William Smith Colleges, Jim Ryan (editor), Hobart & William Smith Colleges, Jeremy Wright (editor), University of Michigan-Ann Arbor.

References

Diller, L., R. Wallace. 1986. Aspects of the life history and ecology of the desert night snake, Hypsiglena torquata deserticola: Colubridae, in southwestern Idaho. Southwestern Naturalist , 31: 55-64. Accessed February 20, 2012 at http://www.jstor.org/stable/3670960?seq=1 .

Dundee, H. 1950. Additional Records of Hypsiglena from Oklahoma, with Notes on the Behavior and the Eggs. Herpetologica , 6/2: 28-30. Accessed February 20, 2012 at http://www.jstor.org/stable/10.2307/3889887 .

Goldberg, S. 2001. Reproduction in the night snake, Hypsiglena torquata (Serpentes: Colubridae), from Arizona. The Texas Journal of Science , 53/2: 210. Accessed February 20, 2012 at http://www.freepatentsonline.com/article/Texas-Journal-Science/78359396.html .

Gregory, P. 1996. The occurrence of the night snake, Hypsiglena torquata, in British Columbia, with comments on its body size and diet. Canadian Field Naturalist , 110/4: 620-625. Accessed February 20, 2012 at http://apps.webofknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=1&SID=3AmN75Jgj6fF7b7mnci&page=1&doc=1 .

Hammerson, G., D. Frost, G. Santos-Barrera, J. Vasquez Díaz, G. Quintero Díaz. 2012. "Hypsiglena torquata" (On-line). The IUCN Red List of Threatened Species. Accessed February 23, 2013 at http://www.iucnredlist.org/details/full/63823/0 .

Lieb, C., D. Clark. 1973. Notes on reproduction in the night snake ( Hypsiglena torquata ). The Southwestern Naturalist , 18: 248-252. Accessed February 20, 2012 at http://www.jstor.org/stable/10.2307/3670427 .

Mulcahy, D. 2007. Molecular systematics of neotropical cat-eyed snakes: a test of the monophyly of Leptodeirini (Colubridae: Dipsadinae) with implications for character evolution and biogeography. Biological Journal of the Linnean Society , 92/3: 483-500. Accessed February 20, 2012 at http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8312.2007.00855.x/full .

Pizzato, L., M. Cantor, J. de Oliveira, O. Marques, V. Capovilla, M. Martins. 2008. Reproductive ecology of dipsadine snakes, with emphasis on South American species. Herpetologist's League Journals , 64/2: 168-179. Accessed February 20, 2012 at http://www.hljournals.org/doi/abs/10.1655/07-031.1 .

Rodriguez-Robles, J., D. Mulcahy, H. Greene. 1999. Feeding ecology of the desert nightsnake, Hypsiglena torquata (Colubridae). Copeia , 1: 93-100. Accessed February 25, 2013 at http://faculty.unlv.edu/jrodriguez/15.pdf .

Roots, C. 2006. Nocturnal Animals . Westport, CT: Greenwood Press. Accessed February 25, 2013 at http://books.google.com/books?id=YlUQPtK8J9kC&pg=PA38&lpg=PA38&dq=hypsiglena+torquata+vision&source=bl&ots=NYO9rntM0y&sig=eqAetmo3mY9CNbXUFe-CJAv-uPs&hl=en&sa=X&ei=nZYrUce9N4i60QHFhoGYCQ&ved=0CCYQ6AEwBA#v=onepage&q&f=false .

Uetz, P., J. Hallermann. 2012. "Hypsiglena torquata (GÜNTHER, 1860)" (On-line). The Reptile Database. Accessed February 23, 2013 at http://reptile-database.reptarium.cz/species?genus=Hypsiglena&species=torquata .

Vest, D. 1988. Some effects and properties of Duvernoy's gland secretion from Hypsiglena torquata texana (Texas night snake). Toxicon , 26/4: 417-419. Accessed February 20, 2012 at http://www.sciencedirect.com/science/article/pii/0041010188900128 .

Weaver, R. 2008. Distribution, abundance, and habitat associations of the night snake ( Hypsiglena torquata ) in Washington state. Northwestern Naturalist , 89: 164-170. Accessed February 20, 2012 at http://www.academia.edu/378705/Distribution_abundance_and_habitat_associations_of_Hypsiglena_chlorophaea_in_Washington_State .

Weaver, R. 2009. Microhabitat and prey odor selection in Hypsiglena chlorophaea . Copeia , 2009/3: 475-482. Accessed February 20, 2012 at http://www.asihcopeiaonline.org/doi/abs/10.1643/CE-08-094 .

2012. "Hypsiglena torquata: Night Snake" (On-line). Encyclopedia of Life. Accessed February 25, 2013 at http://eol.org/pages/963474/overview .

Walter Feller. 2012. "Night Snake: Hypsiglena torquata" (On-line). Digital Desert. Accessed February 25, 2013 at http://digital-desert.com/wildlife/snakes/night-snake.html .