Overview

Distribution

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).
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occurs (regularly, as a native taxon) in multiple nations

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National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) The 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 90-2,440 meters (300-8,000 feet) (Rossman et al. 1996, Ernst and Ernst 2003, Stebbins 2003).

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Continent: North-America
Distribution: USA (Oregon, California),
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Physical Description

Type Information

Holotype for Thamnophis couchii
Catalog Number: USNM 866
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Pitt River, bank of, Locality In Multiple Counties, California, United States, North America
  • Holotype: Kennicott, R. 1859. U.S. and Pacific Railroad Expedition and Survey of California and Oregon. 10 (Part 4, No. 4): 10.
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Ecology

Habitat

Habitat and Ecology

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
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Comments: 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).

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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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Trophic Strategy

Comments: Preys on invertebrates (e.g., earthworms and leeches), amphibians and their larvae, fishes and their eggs.

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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 - 300

Comments: This species is represented by a large number of occurrences (subpopulations).

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Global Abundance

10,000 - 1,000,000 individuals

Comments: Adult population size is unknown but presumably exceeds 10,000. This snake is locally common in various parts of its range.

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Life History and Behavior

Cyclicity

Comments: Primarily diurnal, but also active in the early evening on warm days. Inactive in cold temperatures or extreme heat.

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Life Expectancy

Lifespan, longevity, and ageing

Maximum longevity: 7.7 years (captivity)
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Reproduction

Viviparous. See Hansen (2002, Herpetol. Rev. 33:142).

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Thamnophis couchii

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2007

Assessor/s
Hammerson, G.A.

Reviewer/s
Cox, N., Chanson, J.S. & Stuart, S.N. (Global Reptile Assessment Coordinating Team)

Contributor/s

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.
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National NatureServe Conservation Status

United States

Rounded National Status Rank: N4 - Apparently Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G4 - Apparently Secure

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Population

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
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Global Short Term Trend: Relatively stable (=10% change)

Comments: Extent of occurrence, area of occupancy, number of subpopulations, and population size probably are relatively stable or declining at a rate of less than 10 percent over 10 years or three generations.

Global Long Term Trend: Increase of 10-25% to decline of 30%

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Threats

Major Threats
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).
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Degree of Threat: Unknown

Comments: 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).

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Management

Conservation Actions

Conservation Actions
Some occurrences are in protected areas.
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Names and Taxonomy

Taxonomy

Comments: 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, 2008; Ernst and Ernst 2003).

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