Eastern Mud Snake (Farancia abacura)

Description:    The Eastern Mudsnake is a large, glossy, and highly aquatic species, with adults typically ranging from 3.5-4.5 ft (1-1.3 m) in total length, with large females exceeding 6.5 ft (2 m). They are stout-bodied with smooth, shiny scales. Their bodies are jet black and iridescent blue-purple in sunlight. The belly is patterned with alternating red and black bars that may extend upward along the sides of the body as partial triangular “bands”. The scales on the chin, lips, and throat are yellow with black spotting. The head is short and blunt; the tail ends in a sharp spine-like scale, and the eyes are relatively small. Sexual dimorphism is subtle, with females being slightly larger and heavier-bodied than males. They have a divided anal plate, though some individuals at the Savannah River Site show double anal plates. They are considered among the most beautiful and sought-after snake species in the United States. Much of the life-history information we have on Farancia (especially juvenile emergence and movements around Carolina bays) comes from studies conducted at the Savannah River Ecology Lab in South Carolina.

Range and Habitat:    Eastern mudsnakes occur throughout the southeastern United States, from southeastern Virginia through the coastal plain of South Carolina and Georgia, throughout Florida, and westward into southwestern Alabama. West of Alabama, the western mudsnake becomes more prevalent. They are strongly associated with aquatic habitats and are most abundant in shallow, heavily vegetated wetlands with muddy bottoms, including Carolina bays, cypress swamps, slow-moving creeks, and marshes. They are considered one of the most aquatic North American snakes, but can occasionally be found more than a kilometer (>.5 miles) from wetlands. These large terrestrial activities are often linked to nesting behavior or drought emigration.

Habits:    Eastern Mudsnakes are primarily nocturnal and spend much of their time submerged or burrowed in mud along wetland margins. They are secretive and have low detectability, with most observations being incidental, from road surveys, or from intensive aquatic snake trapping using minnow traps. Studies show that individuals have small home ranges, often confined to a single wetland. However, movement activity increases significantly after heavy rainfall or seasonal flooding. They are most frequently encountered on warm, rainy summer nights when they cross roads that intersect wetland habitats.

They are highly specialized predators, feeding primarily on large aquatic salamanders such as Siren, Amphiuma, and dwarf Sirens. These prey items make up nearly the entirety of their diet in most populations, though some populations occasionally consume tadpoles or fish. Mudsnakes subdue their prey by biting and coiling around them, and by pressing the sharp spine-like tail scale into their prey to help manipulate and immobilize it. The specialization of large salamanders ties the species closely to healthy wetland ecosystems that support robust Siren and Amphiuma populations. Confirmed predators include alligators, coral snakes, eastern indigo snakes, cottonmouths, egrets, and river otters. That said, predation records are minimal relative to many other snakes due to their secretive nature.

Breeding occurs in spring, and females lay egg clutches in summer. Nest sites are terrestrial, typically in rotting logs, mammal burrows, or beneath decaying vegetation, often close to wetlands but sometimes tens of meters away. Clutch sizes average 20-30 eggs but can exceed 100 with very large females. Females occasionally remain with their eggs until hatching, suggesting some degree of parental care, but this has seldom been studied. Hatchlings emerge from late summer to early fall, measuring 8-12 in (20-30 cm). Juveniles appear as miniature versions of adults but are often more brightly colored.

Conservation Status:    Eastern Mudsnakes are declining in parts of their range due to wetland drainage, habitat fragmentation, road mortality, disease (e.g., snake fungal disease), and declines in their salamander prey. They are heavily reliant on healthy, suitable wetlands, yet over 50% of global wetlands have been lost since 1900 and continue to be lost due to increased human development and resource use. Their secretive nature leads to very low detection rates in monitoring programs, making population assessments difficult. Studies at the University of Georgia’s Savannah River Ecology Laboratory suggest that populations are highly vulnerable to wetland alteration and drought, given their reliance on specific aquatic prey and muddy bottomed wetlands. Preserving fishless wetlands with abundant sirens and amphiumas, along with the adjacent upland areas where they nest and overwinter, is critical to protecting healthy populations of these snakes. Eastern mudsnakes are protected by law in both Georgia and South Carolina.

Pertinent References

• D’orgeix, C.A., & T. Mathies. 2013. Terrestrial movements of the Red-bellied Mudsnake (Farancia abacura) and Rainbow Snake (F. erytrogramma). Herpetological Review 44:208-213
• Plummer, M.V., et al. 2020. Red-bellied Mudsnake home ranges increase with precipitation in an isolated wetland. Herpetological Conservation and Biology 15:160-168
• Semlitsch, R.D., J.H.K. Pechmann, & J.W. Gibbons. 1988. Annual emergence of juvenile Mud Snakes at aquatic habitats. Copeia 1988:243-245
• Herpetological Review 55(1):115 (2024) – “FARANCIA ABACURA (Red-bellied Mudsnake). Predation.”