Narrow-headed garter snake

Narrow-headed garter snake
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	Colubridae
Subfamily:	Natricinae
Genus:	Thamnophis
Species:	T. rufipunctatus
Binomial name
	Thamnophis rufipunctatus; (Cope, 1875)
Synonyms
	Chilopoma rufipunctatum Cope, 1875; Atomarchus multimaculatus Cope, 1883; Eutaenia multimaculata ; – Cope, 1886; Thamnophis rufipunctatus ; – Stebbins, 1985; Nerodia rufipunctatus ; – Chiasson & Lowe, 1989; Thamnophis rufipunctatus ; – Rossman et al., 1996;

The narrow-headed garter snake, Thamnophis rufipunctatus, is a threatened species of garter snake, endemic to the southwestern United States and adjacent northwestern Mexico. Its common names also include narrowhead garter snake and narrowhead watersnake.

Geographic range

It is found in Arizona and New Mexico, and in the Mexican states of Chihuahua and Durango.^[2]

Habitat and behavior

It is found near river banks or streams. This species usually sheds its skin when it is in water.

Description

The snake is blue-grey to olive-grey, or greenish to brown, and it has brown, orange, or black spots on the back. The total length of adults is 32-44 in (about 81–112 cm). It has eight or 9 upper labial scaless, one of which enters the eye, two or three preocular scales, two to four postoculars, and one anterior temporal scale.

The keeled dorsal scales are arranged in 21 rows at midbody. Ventrals number 152-177; the anal plate is entire; the subcaudals number 65-87, and are divided.^[3]

Diet

These snakes are piscivorous, meaning they only eat fish. Furthermore, their primary prey species are soft-rayed fishes, which are currently on declines in narrow-headed gartersnake habitat due to invasive spiny-rayed fishes such as green sunfish. Spiny-rayed fishes can choke these snakes when eaten, however the snakes have been documented preying on them when no other food sources are present.

Threatened species

A major cause of the rapid decline of this species of garter snake is the introduction and subsequent invasion of non-native crayfish into their habitats, which feed on both the neonatal snakes and the native fish that serve as the narrow-headed garter snake's primary food source.

Subspecies

Three subspecies are recognized, including the nominate subspecies:

T. r. nigronuchalis Thompson, 1957
T. r. rufipunctatus (Cope, 1875)
T. r. unilabialis W. Tanner, 1985^[4]

Some authorities consider T. r. nigronuchalis to be a full species, i.e., Thamnophis nigronuchalis.^[2]

References

^ ITIS (Integrated Taxonomic Information System). www.itis.gov.
^ ^a ^b ^c The Reptile Database. www.reptile-database.org.
^ Smith, Hobart M., and Edmund D. Brodie, Jr. 1982. Reptiles of North America: A Guide to Field Identification. Golden Press. New York. 240 pp. ISBN 0-307-13666-3.(Thamnophis, p. 144; Thamnophis rufipunctatus, pp. 152-153.)
^ Dahms Tierleben. www.dahmstierleben.de.

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[1] ITIS (Integrated Taxonomic Information System). www.itis.gov.

[RDB-2] The Reptile Database. www.reptile-database.org.

[3] Smith, Hobart M., and Edmund D. Brodie, Jr. 1982. Reptiles of North America: A Guide to Field Identification. Golden Press. New York. 240 pp. ISBN 0-307-13666-3.(Thamnophis, p. 144; Thamnophis rufipunctatus, pp. 152-153.)

[4] Dahms Tierleben. www.dahmstierleben.de.

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