occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
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).
Distribution: USA (Oregon, California),
Catalog Number: USNM 866
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
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.
Habitat and Ecology
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).
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.
Comments: Preys on invertebrates (e.g., earthworms and leeches), amphibians and their larvae, fishes and their eggs.
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).
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.
Life History and Behavior
Comments: Primarily diurnal, but also active in the early evening on warm days. Inactive in cold temperatures or extreme heat.
Lifespan, longevity, and ageing
Viviparous. See Hansen (2002, Herpetol. Rev. 33:142).
Molecular Biology and Genetics
Statistics of barcoding coverage: Thamnophis couchii
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N4 - Apparently Secure
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
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%
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).
Names and 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).