Great Plains rat snake (Pantherophis emoryi)

The slender Great Plains rat snake (Pantherophis emoryi) ⁽²⁾ is a medium- to large-sized member of the Colubridae family ^{(4) (5)} and was once considered to be a subspecies of the corn snake (Elaphe guttata) ⁽⁶⁾. Compared to other species of Colubridae, the Great Plains rat snake has a larger head which is distinct from the neck, and is generally more robust in form ⁽³⁾.

This species is typically light grey to brown ^{(2) (3) (4)} with grey, brown or olive black-edged blotches on its back ^{(2) (3) (4) (5) (6)}. A series of spots runs laterally along the body, and these spots occur alternately between the blotches without connecting with them ⁽⁵⁾. A conspicuous feature of the Great Plains rat snake is the marking on the top of its head which resembles a spearpoint ^{(4) (5) (6)} and is formed from two stripes on the neck which meet between the eyes ^{(2) (4) (5)}. The Great Plains rat snake has round pupils ⁽²⁾.

The belly of the Great Plains rat snake is white and is peppered with bold, dark rectangular or square markings ^{(2) (4) (5)} which produce a checker-board pattern ⁽⁵⁾, while the underside of the tail is typically marked with dark stripes ^{(2) (4) (5) (6)}.

The scales along the centre of the snake’s back are weakly keeled ^{(2) (5) (6)}. Interestingly, the underside of the Great Plains rat snake is very flat, forming an angle with the sides which enables the snake to climb effectively ⁽²⁾.

Also known as

Emory rat snake, Emory’s rat snake, Great Plains ratsnake, house snake, Plains ratsnake, prairie rat snake, western corn snake.

Synonyms

Coluber emoryi, Coluber laetus, Coluber rhinomegas, Elaphe emoryi, Elaphe guttata emoryi, Elaphe laeta , Scotophis calligaster, Scotophis emoryi.

Size

Average length: 60 - 150 cm ^{(2) (3)}

Maximum length: 180 cm ⁽²⁾

A primarily nocturnal species ^{(2) (4) (5) (6) (8)}, particularly during periods of warm weather, the Great Plains rat snake is rather secretive ^{(2) (6)} and is seldom seen ⁽⁴⁾. During the day, it tends to take shelter under rocks and logs or within crevices, caves and rodent burrows ^{(2) (4) (6)}. As well as being a terrestrial species, the Great Plains rat snake is known to be arboreal ⁽¹⁾, and is reported to be an excellent climber ⁽⁸⁾.

A very secretive species, the Great Plains rat snake may vibrate its tail when alarmed, much like a rattlesnake ^{(2) (4)}. It may also bite ^{(2) (4)}, although its bite is harmless ⁽⁴⁾, and it will usually void faeces and the contents of its anal scent glands when caught ⁽²⁾.

The Great Plains rat snake typically feeds on small mammals, such as rodents and bats, as well as on lizards, frogs and small birds and their eggs ^{(2) (4) (5) (8)}, which it hunts at night ⁽⁸⁾. As in other snakes, this species uses special organs in its mouth and on its tongue to detect odours and track its prey ⁽⁴⁾. The Great Plains rat snake is non-venomous ^{(2) (4)}, and kills its prey by constriction ⁽²⁾.

The Great Plains rat snake is reported to be active from late March to late September in parts of its range ⁽⁴⁾. Breeding in this species is thought to occur soon after the snake emerges from its overwintering areas ⁽⁴⁾, typically between May and July ⁽²⁾. An egg-laying species ⁽²⁾, the Great Plains rat snake is thought to only produce one clutch per breeding season ⁽⁴⁾. The eggs, which are white with smooth shells ⁽²⁾, are usually laid between late June and early July ⁽⁴⁾. Hatching takes place about eight to ten weeks later ⁽²⁾, typically in September ⁽⁴⁾. The female Great Plains rat snake lays a clutch of 3 ^{(2) (4)} to 37 eggs, although around 16 is more common ⁽²⁾.

Newly hatched young range in length from about 25 to 38 centimetres. Interestingly, female Great Plains rat snakes do not usually start breeding until they are three years old ⁽²⁾.

The Great Plains rat snake is endemic to the United States ⁽¹⁾, where it is found in the central and southern parts of the country ⁽⁷⁾. Its range stretches from south-western Illinois to south-eastern Colorado ^{(2) (3)}, and from eastern New Mexico south through Texas ^{(1) (2) (3) (6)}. In addition, a disjunct population is reported to occur in western Colorado and adjacent eastern Utah ^{(1) (2) (6)}. The Great Plains rat snake is thought to be relatively uncommon in parts of its range, including Arkansas ⁽⁵⁾.

The Great Plains rat snake occurs in a variety of habitats ⁽²⁾, from grasslands and prairies to deserts ⁽²⁾, open woodlands ^{(2) (4) (5)} and shrubland ⁽²⁾. It can be found in mountainous areas ⁽²⁾ and on rocky, wooded hillsides ^{(1) (4) (5)}, and while it typically occurs below elevations of 1,830 metres, this species has been recorded up to 2,200 metres ⁽²⁾.

The Great Plains rat snake is often closely associated with river valleys ⁽²⁾ and other watercourses ^{(1) (6)}, and tends not to venture too far from streams ⁽²⁾. Semi-agricultural and rural residential areas also provide ideal habitat for this species ⁽²⁾ as it frequents man-made structures ⁽⁷⁾ including barns, ranch buildings and abandoned houses ⁽¹⁾, particularly those with large populations of rodents ⁽²⁾.

The Great Plains rat snake is classified as Least Concern (LC) on the IUCN Red List ⁽¹⁾.

The Great Plains rat snake is not known to be facing any major threats, although some populations of this species may be facing localised threats including habitat destruction. However, the Great Plains rat snake is able to tolerate moderate levels of habitat alteration ⁽¹⁾.

There are currently no known conservation measures in place specifically for the Great Plains rat snake. However, this species may benefit from its occurrence in many protected areas within its range ⁽¹⁾. The Great Plains rat snake is listed as an endangered species in Illinois ⁽⁹⁾, and as a Wildlife Species of Concern in Utah ⁽²⁾.

Find out more about the Great Plains rat snake:

• The Reptile Database - Pantherophis emoryi:
  http://reptile-database.reptarium.cz/species?genus=Pantherophis&species=emoryi&search_param=%28%28search%3D%27Pantherophis+emoryi%27%29%29

Find out more about reptile conservation:

• The International Reptile Conservation Foundation:
  http://www.ircf.org/

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

Arboreal

Of or relating to trees; an animal which lives or spends a large amount of time in trees.

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Gland

An organ that makes and secretes substances used by the body.

Keel

A projecting ridge along a flat or curved surface, particularly down the middle.

Nocturnal

Active at night.

Oviparous

An animal that reproduces by laying eggs, which hatch outside the mother’s body.

Prairie

An extensive area of flat or rolling, predominantly treeless grassland, especially the large tract or plain of central North America.

Subspecies

A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.

1. IUCN Red List (March, 2014)
   http://www.iucnredlist.org/
2. Arizona Game and Fish Department - Heritage Data Management System - Pantherophis emoryi (March, 2014)
   http://www.azgfd.gov/w_c/edits/documents/Pantemor.d.pdf
3. The Reptile Database - Pantherophis emoryi:
   http://reptile-database.reptarium.cz/species?genus=Pantherophis&species=emoryi&search_param=%28%28search%3D%27Pantherophis+emoryi%27%29%29
4. Missouri Department of Conservation - Great Plains ratsnake (March, 2014)
   http://mdc.mo.gov/discover-nature/field-guide/great-plains-ratsnake-great-plains-rat-snake
5. Trauth, S.E., Robison, H.W. and Plummer, M.V. (2004) The Amphibians and Reptiles of Arkansas. University of Arkansas Press, Fayetteville, Arkansas.
6. Conant, R. and Collins, J.T. (1998) A Field Guide to Reptiles and Amphibians: Eastern and Central North America. Houghton Mifflin Harcourt, Boston, Massachusetts.
7. Sperry, J.H. and Taylor, C.A. (2008) Habitat use and seasonal activity patterns of the Great Plains ratsnake (Elpahe guttata emoryi) in Central Texas. The Southwestern Naturalist, 53(4): 444-449.
8. Maxwell, T.C. (2013) Wildlife of the Concho Valley. Texas A&M University Press, College Station, Texas.
9. Illinois Endangered Species Protection Board (2011) Checklist of Endangered and Threatened Animals and Plants of Illinois. Illinois Endangered Species Protection Board, Springfield, Illinois.