Reptiles of North Carolina

Scientific Name:	Common Name:		Family (Alpha):

NC Records
COLUBRIDAE Members:
Farancia abacura - Red-bellied Mudsnake

Photo: K. Bischof

Taxonomy

Class: Reptilia

Order: Serpentes

Family: COLUBRIDAE

Subfamily: Dipsadinae

Other Common Name(s): Mud Snake


Taxonomic Comments: Farancia consists of two species of secretive, mid-to-large bodied aquatic dipsadine snakes endemic to the southeastern United States (Gulf of Mexico and Atlantic Coast). No comprehensive molecular phylogeny of the genus has been completed. The taxonomy of F. abacura has been stable over the past century (see Smith [1938], and Karges and McDaniel [1982] for further reading).
Species Comments: Farancia abacura, the Red-bellied Mudsnake, is one of two members of the genus found in North Carolina. It is found primarily in the southeastern United States, ranging from Texas east to the Atlantic coast, and north to southern Virginia. In North Carolina, it is known primarily from the Coastal Plain and Sandhills. Two subspecies are traditionally recognized based on differences in ventral bar counts and location: F. a. abacura (the Eastern Mudsnake) from the western Florida panhandle and central Alabama east to the Atlantic coast (including North Carolina); and F. a. reinwardtii (the Western Mudsnake) from central Alabama and the western Florida panhandle west to Texas. The generic epithet Farancia is a New Latin coined name with apparently no meaning. The specific epithet abacura is supposedly derived from the Greek abakos (an abacus or counting board), referring to the tessellated ventral pattern. Taxonomic References: Smith (1938); Mitchell (1982a); Karges and McDaniel (1982); McDaniel and Karges (1983).

Identification

Description: Red-Bellied Mudsnakes are large snakes with thick bodies with wedge-shaped heads approximately as wide as the neck. Their dorsum is primarily glossy black, sometimes bluish gray, with a distinct sheen; laterally this dark color is interrupted by lateral bars ranging from pink to red in color. The top of the head is primarily black, while the labial, mental, and underside are often yellow-orange to red, with distinct black spots. The venter is the same color as the lateral bars (pink to red), with alternating black blocks crossing. Hatchlings may have distinct cross-lines absent in adults.

Anerythristic (reduction in red pigments) specimens are occasionally found that lack most of the red/pink coloration on the body and head, leaving instead white lateral and ventral bars; per Palmer and Braswell (1995), this occurred in appoximately 8% of the specimens they examined. Others have exhibited some red anteriorly, fading to white posteriorly, and at least one albinistic specimen has been described. A striking specimen recently found in NC exhibited substantial red and black pigment reduction, leaving a largely white body with black dorsal splotches and an almost entirely yellow head.

Morphological Features: Red-Bellied Mudsnakes typically have 19 smooth scale rows with no reduction down the body. Ventral counts range from 167-208 (NC specimens: 173-198; Palmer and Braswell, 1995), with 31-55 (32-49) subcaudals and a divided anal plate. The tail ends in a noticably conical spine. Head scale counts are typically as follows: 7 supralabials, 8-9 infralabials, 1 nasal, 1 internasal, 1 loreal, 0 preoculars, 2 postoculars, and 1+2 temporals. Palmer and Braswell (1995) noted some variation in scalation across multiple specimens in NC.

These are large snakes, with a maximum reported total length of 207 cm (81.5 inches). Tail lengths range from 7-19% of total length. Females reach larger size than males, have smaller tail lengths relative to body, and average more ventral scales and fewer subcaudal scales. Males are smaller on average but with longer, stouter tails relative to body length, meaning fewer ventrals and more subcaudals. Either sex may exhibit anal ridges on the body scales near the anal plate (typically more pronounced in males).

Red-Bellied Mudsnakes have somewhat enlarged posterior teeth, but lack enlarged fangs or any capacity to produce venom. They are completely harmless to humans and pets, and almost never attempt to bite. When captured, Red-Bellied Mudsnakes may poke the tailspine into the collector, but despite southern folklore declaring the tail spine dangerous, it is entirely harmless and will not break skin.

Technical Reference: McDaniel and Kargas (1983); Palmer and Braswell (1995); Ernst and Ernst (2003).

Field Guide Descriptions: Beane et al. (2010).

Online Photos: Google iNaturalist GBIF

Observation Methods: Passive trapping with partially-submerged minnow traps or larger "trashcan traps" can be effective at capturing foraging aquatic snakes, including F. abacura (Luhring and Jennison, 2008; Durso et al., 2011 and references therein).

Distribution in North Carolina

Distribution Comments: Red-Bellied Mudsnakes are found in eastern North Carolina throughout the Coastal Plain and extending into the eastern Piedmont and Sandhills. They are entirely absent from the western Piedmont and Mountains. Parlin et al. (2019) reported this species from the Outer Banks (Dare Co.).
Distribution Reference: Palmer and Braswell (1995); Ernst and Ernst (2003); Beane et al. (2010)
County Map: Clicking on a county returns the records for the species in that county.

Key Habitat Requirements

Habitat: Red-Bellied Mudsnakes inhabit a variety of still or sluggishly flowing waters in the Coastal Plain, including ponds, marshes, swamps, canals, and slow-flowing streams, especially where there is abundant floating or emergent vegetation (Palmer and Braswell, 1995; Beane et al., 2010).

Biotic Relationships: Mudsnakes primarily prey on sirens and amphiumas, as well as larval ambystomatid salamanders (Palmer and Braswell, 1995; Durso et al., 2013).

They are known prey of wading birds (such as egrets), ophiophagous snakes, and alligators (Ernst and Ernst, 2003; Abercrombie and Hofmann, 2021).

Life History and Autecology

Breeding and Courtship: Females reach sexual maturity between 85-92 cm SVL, or approximately two and a half years old. Males are considered mature at SVLs between 60-72.5 cm. Mating occurs in the spring and summer (April to July). Females build nest burrows (often in the rotting vegetative remains of American Alligator nests) and remain with the eggs after oviposition (Riemer, 1957).

Reproductive Mode: Mudsnakes are oviparous and may lay eggs from early spring to September; these typically hatch in later summer or early fall (August-October). Clutches average 25 white, smooth, elliptical eggs averaging 3.25 x 1.93 cm in size.

Hatchlings are 18.1-23.9 cm in total length (Palmer and Braswell, 1995) and weigh 2-8 g (Ernst and Ernst, 2003).

Aquatic Life History: Mudsnakes are highly aquatic, and seem to prefer shallow, standing water over saturated mud where lots of standing vegetation and submerged shelter are present. Neill (1964) noted that they were rarely found in the same habitats as the closely related Rainbow Snakes, and Palmer and Braswell (1995) noted that the only areas of direct sympatry between these species in North Carolina are Lake Ellis (Craven Co.), Holts Lake (Johnston Co.), and Merchants Millpond (Gates Co.).

Terrestrial Life History: Mudsnakes are highly aquatic and notoriously secretive, making them difficult to find even in areas of local abundance. They will disperse overland away from water, especially if local water sources are drying up, and are known to hibernate below ground or in rotting stumps (Steen et al., 2013). In keeping with their secretive nature, Mudsnakes are most active at night, though they can be encountered during the day crossing roads from one body of water to another or on the edges of water bodies. They have been recorded in North Carolina in every month but November; most records are from May to July.

Home range estimates are not known from North Carolina. Elsewhere, Mudsnake home ranges seem to be closely correlated to available wetlands and precipitation, and range size may vary year-to-year. In a study in Arkansas based in an isolated pond, home ranges were confined to the pond and averaged 0.66 hectares (6600 m²; Plummer et al. 2020), but a study in a more expansive wetland in Missouri found much larger home ranges, up to 22 ha (22,000 m²; Schepis, 2013).

General Ecology

Adverse Environmental Impacts

Interactions with Humans: Though primarily aquatic, mudsnakes will move over land, and as such are occasionally killed on roads by motor vehicles (Steen et al., 2013).

Status in North Carolina

NHP State Rank: S4

Global Rank: G5

Photo Gallery for Farancia abacura - Red-bellied Mudsnake		16 photos are shown.
	Recorded by: Erich Hofmann Columbus Co. Comment:	Recorded by: Erich Hofmann Columbus Co. Comment:
	Recorded by: W. Morris Wayne Co. Comment:	Recorded by: Erich Hofmann Craven Co. Comment:
	Recorded by: Erich Hofmann Craven Co. Comment: large male found crossing road early am, tail spine missing (old injury)	Recorded by: Erich Hofmann Craven Co. Comment: DOR, female
	Recorded by: J. Owen, J. Davis, C. Helms New Hanover Co. Comment:	Recorded by: J. Owen, J. Davis, C. Helms New Hanover Co. Comment:
	Recorded by: Jane Wyche Gates Co. Comment:	Recorded by: K. Bischof Beaufort Co. Comment:
	Recorded by: K. Bischof Beaufort Co. Comment:	Recorded by: K. Bischof Beaufort Co. Comment:
	Recorded by: K. Bischof Beaufort Co. Comment:	Recorded by: K. Bischof Beaufort Co. Comment:
	Recorded by: K. Bischof Beaufort Co. Comment:	Recorded by: K. Bischof Beaufort Co. Comment:

Farancia abacura - Red-bellied Mudsnake

Photo Gallery for Farancia abacura - Red-bellied Mudsnake

16 photos are shown.