The narrow-headed garter snake, ''Thamnophis rufipunctatus'', is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

garter snake Garter snake is a common name for generally harmless, small to medium-sized snakes belonging to the genus ''Thamnophis'' in the family Colubridae. Native to North and Central America, species in the genus ''Thamnophis'' can be found from the sub ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the southwestern

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and adjacent northwestern

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. Its

common names In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

also include narrowhead garter snake and narrowhead watersnake.

Geographic range

It is found in

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

and

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

, and in the Mexican states of

Sonora Sonora (), officially Estado Libre y Soberano de Sonora ( en, Free and Sovereign State of Sonora), is one of the 31 states which, along with Mexico City, comprise the Administrative divisions of Mexico, Federal Entities of Mexico. The state is d ...

Chihuahua Chihuahua may refer to: Places *Chihuahua (state), a Mexican state **Chihuahua (dog), a breed of dog named after the state **Chihuahua cheese, a type of cheese originating in the state **Chihuahua City, the capital city of the state **Chihuahua Mun ...

and

Durango Durango (), officially named Estado Libre y Soberano de Durango ( en, Free and Sovereign State of Durango; Tepehuán: ''Korian''; Nahuatl: ''Tepēhuahcān''), is one of the 31 states which make up the 32 Federal Entities of Mexico, situated in ...

Habitat and behavior

It is found near

river bank Riverbank or river bank may refer to: *Bank (geography), the bank of a river Places *Riverbank, California *Riverbank, former name of Bryte, California Enterprises and organizations *Riverbank Academy, a special school in Coventry, England * Ri ...

s or

streams A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a stream ...

. It is one of the most aquatic of all garter snakes.

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 (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.

Diet

These snakes are piscivorous, meaning they primarily eat fish. Their diet includes dace, chubs, and both native and introduced trout. They might occasionally prey on salamanders.

Threatened species

The snake has declined in parts of its range, but the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

(IUCN) has classified it as of "

Least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

" because of its wide range, presumably large population, and because the rate of decline is not high. However, its status in Mexico is poorly known; were it in a decline there, it might qualify for a category of higher risk. The decline is attributed to introduced species (

bullfrogs ''Bullfrog'' is a common English language term to refer to large, aggressive frogs, regardless of species. Examples of bullfrogs include: Frog species America *Helmeted water toad (''Calyptocephalella gayi''), endemic to Chile *American bullfro ...

''Lithobates catesbeianus'', fishes, crayfish),

habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

and alteration, and sometimes, needless killing and excessive collecting.

Subspecies

Sometimes three

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

are recognized, including the

nominate subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

: * ''T. r. nigronuchalis''

Thompson Thompson may refer to: People * Thompson (surname) * Thompson M. Scoon (1888–1953), New York politician Places Australia *Thompson Beach, South Australia, a locality Bulgaria * Thompson, Bulgaria, a village in Sofia Province Canada * ...

, 1957 * ''T. r. rufipunctatus'' (Cope, 1875) * ''T. r. unilabialis'' W. Tanner, 1985 However, ''T. r. nigronuchalis'' is now commonly held as a full species, i.e., '' Thamnophis nigronuchalis'', whereas the status of ''T. r. unilabialis'' is more ambiguous; most recent molecular evidence suggests it is a full species as well (''Thamnophis unilabialis'').

References

{{Taxonbar, from=Q2714713 Thamnophis Reptiles of Mexico Reptiles of the United States Reptiles described in 1875 Taxa named by Edward Drinker Cope ESA threatened species

External Links

United States Fish and Wildlife Service Designation of Critical Habitat for the Narrow-Headed Gartersnake