The geographic range of western hognose snakes, Heterodon nasicus, extends from southern Canada to northern Mexico. Its range is bordered to the west by Colorado and Wyoming, and in the east by Illinois.
Biogeographic Regions: nearctic (Native )
Heterodon nasicus searchs for its prey, often by using its upturned nose to dig holes in the ground while looking for toads burrowed into the sand. Toads are the main food item of H. nasicus, and can make up nearly 80 percent of its diet in certain regions. When in the mouths of the snakes, toads will swell in order to make themselves too big to swallow. In order to counter this, H. nasicus has its bigger teeth in the back of its mouth, allowing these snakes to puncture the toads if they try to inflate. Another adaption on the snakes' part is an enlarged adrenal gland, which functions in negating the toxins found in the toads' skin. The enlarged adrenal gland can produce enough adrenalin to counteract the digitaloid (which slows down the predator's heart until the point of death) released by the toads as a means of denfense.
Animal Foods: mammals; amphibians; reptiles; eggs
Primary Diet: carnivore (Eats terrestrial vertebrates)
Heterodon nasicus does play an important role in its ecosystem by keeping toad populations from exploding. It is one of the few species that has the ability to cope with the toads' poison, so it is possible that the removal of this species could in fact alter that particular ecosystem.
Its mild temperament makes H. nasicus an ideal pet snake, because it is extremely docile and rarely bites. Once handled by humans enough, the snakes are calm and there is little or no danger of them biting. This snake has an extremely mild venom, and so does not pose a health risk to humans even if a human manages to get bitten.
In addition to their importance in the pet trade, these snakes help people by controlling toad populations. Without these snakes, the toad population could rise high enough so that the toads would infringe upon human establishments. Domestic animals eating toads might be harmed by their toxins (Allen, 1997).
Positive Impacts: pet trade ; controls pest population
Even though H. nasicus is docile, with venom that is mild, it still has venom that can cause some swelling and discomfort in whomever it bites.
Negative Impacts: injures humans (bites or stings, venomous )
As soon as young western hognose snakes hatch they are fully developed, but just smaller in size at about 14 to 18 centimeters. Within hours the young are fully capable of actively searching out prey.
Heterodon nasicus is not given national status as endangered or threatened. However, because of habitat destruction, the numbers of H. nasicus have declined by a considerable amount in certain regions, and as a result western hognose snakes are listed as threatened or even endangered in some of the states in which they reside. These states include Iowa and Illinois. Numerous human developments have pushed western hognose snakes from their sandy habitat into more wooded areas, where it is ill-equipped for survival. In these states there are programs to help save these snakes' habitats. In the southern states, such as Texas and New Mexico, western hognose snakes are quite common. In these areas there is no shortage of the sandy areas which are optimal for these snakes, so they are able to thrive.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
Heterodon nasicus is a species that lives a solitary lifestyle, and the only time that it needs to communicate with other members of its species is during mating season. This communication occurs when the male snakes pick up a chemical scent that the female produces as she sheds her skin, signaling that she is ready for a mate. Males will track the female by the scent.
Some communication occurs with other species. This communication involves visual signals, noises, and sometimes tactile cues. When western hognose snakes encounter a potential predator, they will at first hiss, and flatten their heads and necks to make themselves appear larger. If this fails to ward off the predator, the snake may strike--although it does not bite, apparently, this movement is threatening. If this fails, the snake will feign death in hopes that the predator will lose interest.
Communication Channels: visual ; tactile ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; infrared/heat ; tactile ; acoustic ; chemical
Various people have questioned whether or not this snake is actually venomous. However, an article published by Michael A. Morris describes the effects that the bite of H. nasicus had on him. He experienced swelling and tenderness of the bitten are for two days, and came to the conclusion that the snake does have venom with hemotoxic effects (Morris 1985).
Heterodon nasicus is found at elevations of 90 to 2400 m. It is found in shortgrass prairie, dry rocky lands, and coastal islands (Johns, 2000). It prefers areas that are for the most part dry and sandy. According to Wright (1957, p. 299) H. nasicus is "Distinctly a prairie species, almost every writer refers it to sandy tracts such as sandy hills, sand dunes, sandy flood plains, sandy prairies, sandy areas, and sandy fine loam." The reason for its preference of sandy areas is that it is a snake that likes to burrow into the soil, mainly to search for food (Wright, 1957; Shaw and Camplbell, 1974).
Range elevation: 90 to 2400 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland
Heterodon nasicus has a life expectancy of around fourteen years in the wild. For the most part this is average in comparison to other snake species.
Typical lifespan
Status: wild: 9 to 19 years.
Typical lifespan
Status: captivity: 15 to 20 years.
In comparison to other snakes, H. nasicus is small to medium in size, with an average length of about 50 centimeters, and a weight between 80 and 350 g. The dorsal side these snakes is grayish brown or a light olive green with approximately 40 dorsal spots that are a darker shade of olive green. ventrum is mainly white, but is black underneath the tail. The head is lighter in color than the body, but is strongly marked with dark brown bands across the top and behind the eyes. Each snake has 23 rows of dorsal scales. Perhaps the most distinguishing characteristic of H. nasicus is its upturned nose, which is uses for digging and burrowing.
Range mass: 80 to 350 g.
Range length: 36 to 93 cm.
Average length: 50 cm.
Heterodon nasicus has two main anti-predator adaptations, both of whihc are behavioral. The first line of defense for this snake is to make itself appear larger by making its head and neck flatter. This flattening is accompanied by extremely loud hissing and blowing, whihc apparently makes the individual seem enraged and dangerous. If this defense fails to ward off a predator, the snake will shift into phase two of its defense. This begins with the snake spasming uncontrollably, and then rolling over on its back, lying motionless. Western hognose snakes will feign death in order to make a predator lose interest. When an indivudual perceives an absence of danger, it will resume its activities.
Known Predators:
Anti-predator Adaptations: aposematic
These snakes are described as polygamous. Females will breed with more than one male throughout the course of the breeding season to ensure fertilization, but apparently males also will breed with multiple females. When a female sheds her skin, a chemical is released. Males pick up this scent and actively search for the females. If the female is receptive upon discovery the two will copulate.
Mating System: polygynandrous (promiscuous)
The mating season for H. nasicus occurs between the months of June and August, as males actively seek out females to breed with. Females lay from 4 to 23 eggs between June and August. Once the eggs have been fertilized they are buried in the sand and hatch in 52 to 64 days.
Breeding season: Breeding occurs in Spring and Summer.
Range number of offspring: 4 to 23.
Range gestation period: 52 to 64 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; sexual ; fertilization ; oviparous
Average number of offspring: 13.
Average age at sexual or reproductive maturity (male)
Sex: male: 730 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 730 days.
After having buried its eggs, H. nasicus invests no parental care into its young. This is why it is important that the young are fully developed upon hatching.
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female)
When disturbed, H. nasicus will make mock strikes by jerking its body and flatten its head and neck. Its not known to bite but according to Tennant (2003), a man who was bitten on the finger, with the snake having chewed on for several minutes, experienced an anti-coagulant effect, followed by mild swelling and numbness that reached his elbow after several hours. No permanent damage occurred.
Western hognose snake
H. nasicus can reach a maximum size of about 90 cm, averaging between 38 to 64 cm. The dorsal pattern consists of sandy ground colored scales contrasted by more than 35 brown dorsal blotches from the snout to the vent in males and more than 40 in females. The flanks are speckled with brown scales and large spots. Like in other members of its genus, a prominent brown band crosses the eye to the forehead. The ventral scales are coal-black colored with white, yellow or pale orange edges. (Tennan, 2003).
H. nasicus has a more generalized diet than other members of its genus, which prey predominantly on toads. They will consume small mammals, amphibians, lizards and smaller snakes (Tennant, 2003).
Mostly active during the morning and evening, sheltering at night and during cold weather by burrowing into sandy soil, or, when on the surface, submerged in leaf litter (Tennant, 2003).
Short and mixed grass prairies in broken terrain where canyons provide seasonal water, gravelly or sandy soil which allows burrowing, and leaf litter litter or ground cover which provide shelter (Tennant, 2003).
Oviparous
The western hognose snake (Heterodon nasicus) is a species[2] of snake in the family Colubridae. The species is endemic to North America.
The specific name, nasicus, is from the Latin nasus ("nose"), in reference to the upturned snout.[3]
The subspecific name, gloydi, is in honor of American herpetologist Howard K. Gloyd (1902–1978).[4]
The subspecific (or specific) name, kennerlyi, is in honor of American naturalist Caleb Burwell Rowan Kennerly.[4]
Common names for Heterodon nasicus include blow snake, bluffer, faux viper, plains hognose snake, prairie hognose snake, spoonbill snake, spreadhead snake, Texas hognose snake, Texas rooter, and western hognose snake.
Some authors elevate H. n. kennerlyi, also known as the Mexican hognose snake, to species level. Those same authors have subsumed H. n. gloydi into H. nasicus so that there are only two species (H. nasicus and H. kennerlyi) and no subspecies.
The western hognose snake is a relatively small, stout-bodied snake. Its color and pattern is highly variable between subspecies, although most specimens appear much like rattlesnakes to the untrained eye, which appears to be Batesian mimicry. Males are considerably smaller than females, with adults rarely exceeding a total length (including tail) of 40–50 cm (15–20 inches). This snake gets its common name, "hognose", from the modified rostral (nose) scale that is formed in an upturned manner, providing a very "hog-like" look. Additionally, this adaptation makes these snakes adept burrowers.[5]
The species is not dangerous to humans, but there exists scientific debate regarding whether the mild toxins in the hognose's bite result from saliva, harmful to its preferred wild food source – toads – or an extremely mild venom produced in glands connecting to the hognose's minuscule rear fangs. In either case, no deaths or systemic effects from the extremely rare bite from this rear-fanged snake have been recorded.[6] Although bites may uncommonly be medically significant, the species is not regarded as venomous.[2]
In captivity, the species has been bred into about 52 different "designer" color morphs.[7]
The western hognose snake occurs from southern Canada throughout the United States to northern Mexico. It frequents areas with sandy or gravelly soils, including prairies, river floodplains, scrub and grasslands, semi-deserts, and some semiagricultural areas.[1] It has been found at elevations of up to 2,500 m (8,200 feet).[6]
The western hognose snake is primarily diurnal. It is typically a docile snake (though known to be highly defensive in some individuals). If threatened (or perceiving a threat), it may flatten its neck (much like a cobra), hiss, and make 'mock' or 'bluff' strikes if harassed, which are strikes made at an intruder but with the snakes' mouth closed. Subsequently, even when further harassed, western hognose snakes virtually never bite as a self defense mechanism, but will instead usually resort to playing dead.[8][9] Although it is more common that it will flatten its head, some individuals may puff up, filling the throat with air. This is more common with adolescent males.
In the wild, the western hognose snake feeds predominately on amphibians, such as large and medium-sized tree frogs, as well as small or medium-sized toads and small lizards. There have been accounts of H. nasicus eating the occasional rodent in the wild as well. Not being a true constrictor, Heterodon bites and chews, driving the rear fangs into the prey as a way of introducing the saliva to help break down the toxins from toads. There have been many cases of hognose snakes in captivity that will not eat for about two to three-and-a-half months, from the months January to mid March. This is because hognose snakes' instinct is to brumate underground during the winter months.
Adult western hognose snakes have been observed in copulation as early as February and March. The species is oviparous, with females laying 4–23 elongate, thin-shelled eggs in June–August. The eggs take approximately 60 days to hatch. Each hatchling is 13–23 cm (5–9 in) in total length, and reaches sexual maturity after approximately two years (this is predominantly based on size, not so much age).[10]
Although some local declines have been reported, the species H. nasicus is widespread, has a large overall population size (> 100,000), and is effectively protected by a variety of conservation programs. It is therefore currently classified as Least Concern by the IUCN. The eastern hognose snake (Heterodon platirhinos) is classified as a threatened species in some regions of its range and is therefore protected under those states' laws.[1]
The western hognose snake (Heterodon nasicus) is a species of snake in the family Colubridae. The species is endemic to North America.
