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 ; chemical
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
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.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
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
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 )
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
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.
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 (Incilius 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.
Animal Foods: amphibians; reptiles; eggs; carrion ; insects; terrestrial non-insect arthropods
Primary Diet: carnivore (Eats terrestrial vertebrates, Eats eggs, Insectivore )
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 (Native )
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.
Range elevation: 0 to 2650 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral ; forest ; scrub forest ; mountains
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.
Range lifespan
Status: captivity: 12.2 (high) years.
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.
Range length: 30 to 66 cm.
Other Physical Features: venomous
Sexual Dimorphism: female larger
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.
Known Predators:
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
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.
Breeding interval: Female night snakes breed once during mating season.
Breeding season: Breeding takes place from the spring through early fall.
Range number of offspring: 2 to 6.
Average number of offspring: 3.
Range gestation period: 50 to 60 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; sexual ; fertilization ; oviparous
This species is not known to exhibit any parental investment after eggs are laid.
Parental Investment: no parental involvement
The night snake (Hypsiglena torquata) is a species of rear-fanged colubrid. It is found in Mexico.[3]
Total length is 12–26 in (30–66 cm). It is pale gray, light brown, or beige in color, with dark grey or brown blotches on the back and sides. The night snake's head is rather flat and triangular-shaped and usually has a pair of dark brown blotches on the neck. It also has a black or dark brown bar behind the eyes that contrast against the white or pale gray upper labial scales, and the pupil of the eye is vertical. The belly is white or yellowish. Females are usually longer and heavier than males.
Although the night snake poses no threat to humans, it is slightly venomous and uses this venom to subdue its prey.
The night snake is endemic to Mexico. Not much is known as far as population densities and exact range due to the highly cryptic nature of the night snake.
Night snakes are known to be both crepuscular (most active at dawn and dusk), and nocturnal. They are usually seen at night while crossing roads, but can be found under rocks, boards, dead branches and other surface litter during the day. Night snakes hibernate during the winter months, and are known to aestivate during periods of the summer. They are generally most active from April to October, with peaks of activity usually occurring in June. If threatened, the night snake may coil up and thrust its coils at the threat, while flattening its head into a triangular defensive shape.
Their main prey is lizards. A study in southwestern Idaho found that the night snake's diet consisted mostly of side-blotched lizards (Uta stansburiana) and their eggs. Other prey includes juvenile rattlesnakes and blind snakes, salamanders, frogs, and large insects.
Night snakes mate in the spring, and females lay a clutch of 2–9 eggs from April to August. Eggs hatch in 7 to 8 weeks, usually in late summer. Males reach sexual maturity after one year.
Night snakes are known to be docile and easily handled. Captive night snakes have lived over 12 years.
The night snake (Hypsiglena torquata) is a species of rear-fanged colubrid. It is found in Mexico.
