Thamnophis elegans

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA REPTILIA SQUAMATA NATRICIDAE

Scientific Name: Thamnophis elegans
Species Authority: (Baird & Girard, 1853)
Common Name/s:
English Terrestrial Gartersnake, Western Terrestrial Garter Snake

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2007
Date Assessed: 2007-03-01
Assessor/s: Frost, D.R., Hammerson, G.A. & Hollingsworth, B.
Reviewer/s: Cox, N., Chanson, J.S. & Stuart, S.N. (Global Reptile Assessment Coordinating Team)
Justification:
Listed as Least Concern in view of its wide distribution, tolerance of a broad range of habitats, 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:The species' range extends from central British Columbia, central Alberta, and southwestern Manitoba in Canada, south through all of the western United States (east to western South Dakota, western Nebraska, Colorado, extreme western Oklahoma, and New Mexico) to (disjunctly) northern Baja California. There are many isolated populations around the margins of the main range (Fitch 1983, Rossman et al. 1996, Grismer 2002, Stebbins 2003), notably in the Sierra Nevada and San Bernardino Mountains of California, and Sierra San Pedro Martir in Baja California (subspecies T. c. hueyi). Its elevational range extends from sea level to 3,995 m asl (13,100 feet) (very rarely); usually below 3,355 m asl (11,000 feet) (Hammerson 1999, Stebbins 2003).
Countries:
Native:
Canada; Mexico; United States
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: This species is represented by hundreds of occurrences or subpopulations (e.g., see maps in Fitch 1983, Degenhardt et al. 1996, and Hammerson 1999). The total adult population size is unknown but certainly exceeds 100,000. This snake is very common in many areas. Its extent of occurrence, area of occupancy, number of subpopulations, and population size are probably relatively stable. The isolated southern populations in California and Baja California are much less abundant.
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: This species occurs in a wide variety of habitats, from lowlands to high mountains: grassland, shrubland, woodland, rocky hillsides, and open areas in forests. It is chiefly terrestrial in most areas, but also aquatic in some locations (e.g., high Sierra Nevada). Often in inhabits wetlands and areas near streams, ponds, and lakes.
Systems: Terrestrial; Freshwater

Threats [top]

Major Threat(s): No major threats are known. In high-elevation areas of the southern Sierra Nevada in California, introductions of non-native trout apparently have led to declines in populations of amphibians and possibly also of T. elegans, which may depend on amphibians as a primary food resource (and which may occasionally serve as prey for trout) (Matthews et al. 2002). However, Matthews et al. (2002) did not discuss the historical distribution of T. elegans in their study areas, so the significance of extensive trout introductions in the absence of garter snakes from some areas (John Muir Wilderness) is uncertain. Further study is warranted (e.g., in the mountains of Colorado, T. elegans is a versatile feeder [Hammerson 1999], and garter snake populations may not rely much on amphibian populations).

Conservation Actions [top]

Conservation Actions: Many occurrences of this species are in protected areas.

Bibliography [top]

Degenhardt, W.G., Painter, C.W. and Price, A.H. 1996. Amphibians and Reptiles of New Mexico. University of New Mexico Press, Albuquerque, New Mexico. Xix + 431 pp.

de Queiroz, A. and Lawson, R. 1994. Phylogenetic relationships among garter snakes based on DNA sequence and allozyme variation. Biological Journal of the Linnaean Society 53: 209-229.

Fitch, H.S. 1940. A biogeographical study of the ordinoides Artenkreis of garter snakes (genus Thamnophis). University of California Publications in Zoology 44: 1-150.

Fitch, H.S. 1983. Thamnophis elegans. Catalogue of American Amphibians and Reptiles 320: 1-4.

Grismer, J.L. 1994. Food observations of the endemic Sierra San Pedro Mártir garter snake (Thamnophis elegans hueyi) from Baja California, Mexico. Herpetological Natural History 2: 107-108.

Grismer, L.L. 2002. Amphibians and Reptiles of Baja California, Including its Pacific Islands and the Islands in the Sea of Cortés. University of California Press, Berkeley and Los Angeles, California.

Hammerson, G.A. 1999. Amphibians and reptiles in Colorado. Second edition. University Press of Colorado, Boulder, Colorado.

IUCN. 2007. 2007 IUCN Red List of Threatened Species. Available at: www.iucnredlist.org. (Accessed: 12th September 2007).

Matthews, K.R., Knapp, R.A. and Pope, K.L. 2002. Garter snake distributions in high-elevation aquatic ecosystems: is there a link with declining amphibian populations and nonnative trout introductions? Journal of Herpetology 36: 16-22.

Murray, K.F. 1955. Herpetological collections from Baja California. Herpetologica 11: 33-48.

Rossman, D.A., Ford, N.B. and Seigel, R.A. 1996. The Garter Snakes. University of Oklahoma Press, Norman, Oklahoma and London, UK.

Stebbins, R.C. 2003. A Field Guide to Western Reptiles and Amphibians. Third Edition. Houghton Mifflin Company, Boston, Massachusetts.

Welsh, H.H. 1988. An ecogeographic analysis of the herpetofauna of the Sierra San Pedro Martir region, Baja California with a contribution to the biogeography of the Baja California herpetofauna. Proceedings of the California Academy of Science, 4th series 46: 1-72.

Citation: Frost, D.R., Hammerson, G.A. & Hollingsworth, B. 2007. Thamnophis elegans. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 17 April 2014.
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