Western hog-nosed snake (Heterodon nasicus)

Also known as: western hognose snake
Synonyms: Heterodon gloydi, Heterodon kennerlyi
KingdomAnimalia
PhylumChordata
ClassReptilia
OrderSquamata
FamilyDipsadidae
GenusHeterodon (1)
SizeAdult length: 38 - 83 cm (2)
Hatchling length: 15 - 19 cm (2)
Top facts

The western hog-nosed snake is classified as Least Concern (LC) on the IUCN Red List (1).

The western hog-nosed snake (Heterodon nasicus) is a medium sized snake that is heavy-bodied in relation to its length (2) (3) (4) (5) (6). Individuals vary from a light, sandy-brown to reddish-brown, with a pattern of contrasting darker grey or brown blotches extending from the back of the head to the tail (2) (3) (4) (5). This species has a black-coloured belly with irregular markings in white, yellow or orange, forming a checkered pattern (2) (3) (4). Female western hog-nosed snakes are generally larger than the males (2) (3).

The western hog-nosed snake exhibits the distinct upturned snout that is characteristic of all hognose snake species (2) (3) (4). It is a mildly venomous species of snake, with enlarged, un-grooved teeth towards the rear of the upper jaw (2) (4). The western hog-nosed snake uses its venom to subdue struggling prey, and only bites as a feeding response, never in defence (2) (4). 

The western hog-nosed snake is listed as having two synonyms; Heterodon gloydi andHeterodon kennerlyi on the IUCN Red List (1), but these have been recognised as separate species in several publications, and as recently as 2009 (2) (3) (6).

The western hog-nosed snake is widespread in North America (5). It is found as far north as southern Canada, southwards through Arizona and Wyoming to northern Mexico, and east to Illinois (2) (6).

The western hog-nosed snake is a terrestrial species that is found in a variety of habitats (2)(5). It favours habitats with sandy, loose soil into which the snake can easily burrow, such as prairies, grasslands, rocky environments, semi-arid regions and coastal or floodplain habitats (2) (3) (4) (5) (6).

The western hog-nosed snake feeds on a range of different amphibians, lizards, rodents and eggs (2) (4). They use their enlarged teeth in the rear of its mouth to hold and puncture inflated prey, including frogs and toads (5). The shovel shaped nose, characteristic of hognose snake species, is used for digging, and western hog-nosed snakes have been observed following turtle nest scent trails to locate and dig for eggs (4).

The western hog-nosed snake breeds in the spring, and lays clutches of between 4 and 25 thin shelled eggs during the summer from June - August (2) (4). The eggs hatch after approximately 60 days (2). Western hog-nosed snake hatchlings are around 15-19 cm in length and reach sexual maturity after two years (2).

The western hog-nosed snake is active during the day (2). It is a docile species of snake, and only bites when feeding, not in self-defence (2) (4). If harassed, it will mock strike, and spread its head and neck widely as part of a defensive bluff (2) (4) (5). The western hog-nosed snake might engage in a routine to feign its own death, known as ‘playing possum’ (2) (4) (5) (7). This elaborate strategy involves the snake suddenly turning belly up and writhing violently for a few moments, before lying still with its mouth open and tongue protruding (4) (7). This aims to cause the predator to cease its attack (5) (7).

The western hog-nosed snake may suffer from habitat loss through conversion of prairie habitat for agricultural use, but this is not considered to be a significant threat (1).

This species has been listed as threatened in Illinois and South Dakota, and as endangered in Iowa, but is more commonly found in the southern end of its geographic range, where it holds no particular conservation status (2). It is thought that there is enough protected habitat for this species over a wide distribution of federal, state and private lands to ensure the population trend remains stable (1) (2).

Find out more about western hog-nosed snake conservation here:

Illinois department of natural resources
http://dnr.state.il.us/education/snakes/snakeconservation.HTM

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

  1. IUCN Red List (October 2013)
    http://www.iucnredlist.org/
  2. Mobile Reference (2009) The Illustrated Encyclopedia of North American Reptiles and Amphibians: An Essential Guide to Reptiles and Amphibians of USA, Canada, and Mexico. Mobile Reference
  3. Dixon, J.R. and Werler, J.E. (2000) Texas Snakes: A Field Guide. University of Texas Press, Austin
  4. Stebbins, R.C. (2003) A Field Guide to Western Reptiles and Amphibians: Third Edition. Houghton Mifflin Harcourt, New York
  5. Holman, J.A. (2000) Fossil Snakes of North America: Origin, Evolution, Distribution, Paleoecology. Indiana University Press, Bloomington
  6. Weinstein, S.A. and Keyler, D.E. (2009) Local envenoming by the Western hognose snake (Heterodon nasicus): A case report and review of medically significant Heterodon bites. Toxicon, Volume 54: pages 354-360
  7. Halliday, T. And Adler, K. (2002) The new Encyclopedia of Reptiles and Amphibians. Oxford University Press