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Thamnophis couchii

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA REPTILIA SQUAMATA NATRICIDAE

Scientific Name: Thamnophis couchii
Species Authority: (Kennicott, 1859)
Common Name(s):
English Sierra Gartersnake, Western Aquatic Garter Snake
Taxonomic Notes: Thamnophis hammondii, T. gigas, and T. atratus (including subspecies hydrophilus and aquaticus) formerly were included in Thamnophis couchii but now are recognized as distinct species (Rossman et al. 1996; Crother et al. 2000, 2003; Ernst and Ernst 2003).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2007
Date Assessed: 2007-03-01
Assessor(s): Hammerson, G.A.
Reviewer(s): Cox, N., Chanson, J.S. & Stuart, S.N. (Global Reptile Assessment Coordinating Team)
Justification:
Listed as Least Concern in view of its relatively wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.

Geographic Range [top]

Range Description: This species is endemic to the west of the United States. Its range includes the Sierra Nevada, California, north to the Pit River, south to the Tehachapi Mountains, and extends east along major rivers to the Owens Valley and west-central Nevada, at elevations of about 90 to 2,440 m (300 to 8,000 feet) (Rossman et al. 1996, Ernst and Ernst 2003, Stebbins 2003).
Countries:
Native:
United States
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is represented by a large number of occurrences (subpopulations). The adult population size is unknown but presumably exceeds 10,000. This snake is locally common in various parts of its range. The extent of occurrence, area of occupancy, number of subpopulations, and population size are probably relatively stable or declining at a rate of less than 10% over 10 years or three generations.
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: Habitats of this highly aquatic snake include pools of permanent or seasonal streams (often rocky), meadow ponds, lakes, reservoirs, and associated riparian zones (e.g., cottonwood, willow, sycamore, alder), in areas with oak woodland, grassy valleys, chaparral, montane coniferous forest, or (east of the Sierra crest) pine-juniper-sagebrush (Rossman et al. 1996, Ernst and Ernst 2003, Stebbins 2003).
Systems: Freshwater

Threats [top]

Major Threat(s): No major threats are known. Anecdotal evidence suggests that some populations may be declining as a result of predation by introduced non-native fishes (Rossmand et al. 1996).

Conservation Actions [top]

Conservation Actions: Some occurrences are in protected areas.

Citation: Hammerson, G.A. 2007. Thamnophis couchii. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 17 September 2014.
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