Average snout-vent length is 90-120 mm. Large males have snout-vent length between 110 and 120 mm, and females reach snout-vent lengths between 130 and 140 mm, and up to 155 mm. The dorsum is blackish green and unmarked or greyish olive with a pattern of small, well separated dark markings of irregular, angular, or linear shape. These markings may be larger, more rounded, and interconnected. Its venter is medium to dark grey or black with light spots or worm-like markings. A light girdle usually outlines the groin. Males have a throat which is dark grey or black washed with yellow and often bears prominent yellow spots. Both females and males have smooth to moderately rugose dorsal skin. Some individuals are very rugose and have skin which is heavily wrinkled by large warts and ridges. Rugose individuals have two parallel rows of elongate tubercles dorsolaterally, but these are poorly defined in smooth individuals.
The calls of adult males are a rolling snore or an explosive grunt.

This species is known from the Coastal Plain of the southeastern United States from southern North Carolina (at least formerly) to northern Florida, west to southeastern Mississippi (Conant and Collins 1991).

The river frog can be found in the southeastern portion of the United States. It is found in parts of the following states: Mississippi, Alabama, Georgia, Florida, South Carolina and North Carolina (FCES 1999).

Biogeographic Regions: nearctic (Native )

endemic to a single nation

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Coastal Plain from southern North Carolina (at least formerly) to northern Florida, west through extreme southern Alabama to southeastern Mississippi (Conant and Collins 1991). Most of the range is in northern Florida, southern Georgia, and southern South Carolina.

R. heckscheri inhabits Coastal Plain river swamps of the southeastern United States from the Cape Fear River drainage in North Carolina southward to northern Florida and westward along the Gulf Coast to the Biloxi River in Mississippi.

The river frog ranges from 3.25 - 4.63 inches in snout-vent length (record length 6.13 inches). The dorsal surface of the frog is a greenish black color. A common field mark is the presence of light spots on the lips; these spots are usually larger on the lower jaw. The skin is more rugose than the skin of most other ranid frogs. The belly ranges from gray to almost black in color, and is marked with light spots or short wavy lines (Conant and Collins 1998). Males often have a yellowish suffusion on the throat. The river frog has no dorsolateral ridges as found in many other ranid frogs. The webbing on the hind feet extend to the last phalanx on the longest toe (Bartlett and Bartlett 1999). Tadpoles of the river frog are rather large, reaching 4 inches before metamorphosis. The tadpoles undergo ontogenetic color changes. Small tadpoles have well-defined light rings around the body, posterior to the eyes, these rings disappear with growth (Bartlett and Bartlett 1999).

Length: 14 cm

Habitat and Ecology

Systems

• Terrestrial
• Freshwater

The river frog is not limited to rivers as its name may imply. They can also be found in and along lakes, ponds, swamps, streams, and marshes. They prefer open, thinly vegetated shoreline habitats (Bartlett and Bartlett 1999).

Aquatic Biomes: lakes and ponds

Comments: Swamps along streams and edges of shallow ponds and impoundments (including beaver ponds). Eggs and larvae develop in permanent swamp waters.

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.

The river frog feeds largely on insects and other invertebrates; they occasionally take small vertebrate prey, such as other ranid frogs of suitable size.

Comments: Metamorphosed frogs probably eat various invertebrates and occasionally small vertebrates. Larvae may eat organic debris, algae, plant tissue, and small invertebrates.

Male river frogs call to attract local females from April into July. The call of larger more mature frogs is a deep, low pitched, roaring snore. Smaller males give off a much higher pitched call than do the larger males. The males will call while sitting in shallow water or on the shore near the waters edge (Bartlett and Bartlett 1999). When the male attracts a female they will go into amplexus. The male will use his enlarged thumbs to grasp the female while fertilizing the eggs as she deposits them (Wright 1932). The female will lay several thousand eggs that form into a surface film, often among emergent vegetation to which they adhere. The tadpoles overwinter and take about one year to metamorphose (Bartlett and Bartlett 1999).

Lays clutch of probably several thousand eggs April to August. Aquatic larval stage lasts 1-2 years.

The river frog is still common in areas of the southeastern United States that still have proper habitat. With the preservation of their habitat the river frog should have no problem persisting in the future (Bartlett and Bartlett 1999).

US Federal List: no special status

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Moderate to broad.

Population

Population Trend

Up until they're 20 mm in length, larvae are black with a conspicuous gold band across the dorsum and no pigment in the tail. Between 21 and 40 mm, melanophores form along the crests of the tail and the gold band starts to fade. At 50-55 mm the dorsum is dark olive covered with tiny, greenish yellow flecks, the venter is purplish, and the tail is edged in black. Larvae transform at or before a size of 158 mm. There are two or three rows of labial teeth above and three below.

Major Threats

Conservation Actions

The river frog does not appear to present any negative attributes concerning the environment or humans.

The river frog are an important species for their aesthetic value, ecological importance, and the consumption of insects, some of which are considered to be pests by humans.