endemic to a single nation

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) The range encompasses the Coastal Plain from North Carolina to southern Florida, and west to Texas, and extends north in the Mississippi Valley to southeastern Missouri and (at least formerly) southern Illinois (Conant and Collins 1991, Palmer and Braswell 1995, Phillips et al. 1999, Johnson 2000, Ernst and Ernst 2003). Introduced and established in southern Texas (Werler and Dixon 2000) and in Sacramento County, California (Balfour and Stitt 2002).

Length: 159 cm

• Terrestrial
• Freshwater

Comments: Habitat consists primarily of vegetated freshwater ponds, lakes, marshes, wet prairies, sluggish streams and rivers, drainage ditches, and swamps, extending in some areas seaward to the edge of salt water meadows and marshes and mangrove swamps (Barbour 1971; Tennant 1997, 1998; Johnson 2000; Werler and Dixon 2000; Ernst and Ernst 2003; Trauth et al. 2004). This snake basks on banks and in edge vegetation. It shelters in bank-side burrows or under vegetative debris.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

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: Eats frogs, toads, salamanders, tadpoles, fishes, and aquatic invertebrates.

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

Estimated Number of Occurrences: 81 to >300

Comments: This species is represented by a very large number of occurrences or subpopulations. It is ubiquitous in suitable habitat throughout most of its range (Gibbons and Dorcas 2004). Werler and Dixon (2000) mapped more than 200 collection sites in Texas alone; hundreds of additional collection sites in Louisiana, North Carolina, and Arkansas were mapped by Dundee and Rossman (1989), Palmer and Braswell (1995), and Trauth et al. (2004).

100,000 to >1,000,000 individuals

Comments: Adult population size is unknown but certainly exceeds 100,000. This snake is locally abundant or common in much of eastern North Carolina (Palmer and Braswell 1995) and Arkansas (Trauth et al. 2004), and it is the most common watersnake in peninsular Florida (Tennant 1997). It is common to uncommon in different parts of its range in Texas (Tennant 1998). It is relatively scarce at the northern periphery of the range in Illinois (Phillips et al. 1999) and Kentucky (Barbour 1971).

In South Carolina, emigrated from a drought-stricken site with low water levels (Seigel et al. 1995).

Comments: Basks by day in cool weather; most active at night, especially after summer rains (Tennant 1984, Mount 1975).

Gives birth to 2-57 young, June to August (average litter size smaller in coastal populations than in inland populations).

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - 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%

Comments: This snake is possibly extirpated at the northern tip of the range in Illinois (Phillips et al. 1999).

Comments: No major threats are known. Locally, some populations have been reduced or eliminated as a result of drainage of wetlands or removal of aquatic vegetation (Phillips et al. 1999). Many are killed each year by people (Trauth et al. 2004), but this does not constitute a major threat.

Global Protection: Very many (>40) occurrences appropriately protected and managed

Comments: Many occurrences are in protected areas.

Comments: Salt marsh populations that were formerly included in this species are now regarded as a distinct species, N. clarkii (Lawson 1987, Lawson et al. 1991); hybrids between clarkii and fasciata occur in disturbed areas.