Farancia erytrogramma

Geographic Range

Rainbow snakes, Farancia erytrogramma , inhabit the southeastern United States. The range of rainbow snakes extends from southern Maryland to south-central Florida, westward to Louisiana, and the Mississippi River. These snakes are also found in the eastern portion of Virginia. Additionally, they inhibit southern Alabama, southeastern Georgia, northeastern South Carolina, and northern North Carolina.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Rainbow snakes are commonly found in swamps, open marshes, rivers (especially slow-moving streams, blackwater creeks), and brackish water. They are more commonly associated with sandy soils. Rainbow snakes can also be found on mountains, in deciduous forests, or burrowed into sand. Rainbow snakes have been found in burrows up to 3.0 meters below the dry sand surface. Young rainbow snakes are commonly found buried under debris, including logs. They may make shelter out of bald cypress ( Taxodium distichum ) tree roots, stone piles and downed logs.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial
• freshwater freshwater

• Terrestrial Biomes
• forest forest
• mountains mountains

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• brackish water brackish water

• Wetlands
• marsh marsh
• swamp swamp

Physical Description

Rainbow snakes are non-venomous, thick-bodied snakes with their main colors being red, black, and yellow. Both sexes have 155 to 177 ventral spots, with females having more spots than males. Scales are smooth and their heads are a little wider than their necks. Their heads are black with red dots on both sides of their heads. There are three longitudinal red stripes across theirs backs. The anal scale is usually divided. Female rainbow snakes have a greater number of posterior scale rows than the males. Adult female rainbow snakes are larger than males, although males have longer, thicker tails. Female total length averages 167.6 cm, while males average 107.4 cm.

At hatching, juvenile rainbow snake length ranges from 8 cm to 19.7 cm. Juvenile rainbow snakes tail tips are pointed but, as they age their tail gradually becomes rounder. Juvenile rainbow snakes resemble adult rainbow snakes but lack any yellow coloration.

Rainbow snakes are distinguished from mud snakes ( Farancia abacura ) by having 2 internasal scales. Mud snakes have just one.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger
• sexes colored or patterned differently
• sexes shaped differently

Development

Little is known about the rainbow snake lifecycle. Eggs incubate for 90 days. Hatchlings stay in the nest during the winter and leave in the summer. Hatchlings begin their first growing season at total lengths of 20 to 30 cm. A year later, rainbow snakes are 45 to 55 cm long. Like all snakes, rainbow snakes exhibit indeterminate growth. The juvenile rainbow snakes look similar to the adult rainbow snakes, except the tail tips of the juveniles are sharper.

• Development - Life Cycle
• indeterminate growth indeterminate growth

Reproduction

Little is known about rainbow snake mating systems. Male rainbow snakes fight each other to prove their strength to sexually-receptive females. Both males and females mate with multiple individuals per breeding season.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Rainbow snakes breed once yearly, in the late spring or summer months. Their breeding season lasts for three months. Female rainbow snakes are oviparous, laying an average of 20 eggs (range 10 to 52 eggs). The gestation period for rainbow snakes is 60 to 80 days beginning in June to August. Females will remain with the eggs for a period of incubation until the eggs hatch. Female rainbow snakes will burrow their eggs from 10.16 to 45.72 cm underground. Female rainbow snakes remain in the nest with the eggs until they hatch, after which females leave. Eggs hatch in the early fall. Once hatched, young receive no parental care. In winter, young hatchlings stay underground near their nest and move to rivers, streams, swamps, and marshes in the spring. Both sexes reach their sexual maturity at 2 to 3 years.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• oviparous oviparous

After mating, the males will leave the females and provide no parental care. The females will lay their eggs somewhere damp in a nest, often stationed close to a wetland. Females will protect and incubate eggs by coiling around them. Once the eggs hatch, females leave and provide no further care.

• Parental Investment
• female parental care female parental care
• pre-fertilization
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Not much has been reported about the lifespan of rainbow snakes in captivity or in the wild. Another member of the genus, Farancia abacura , the mud snake, is known to live 19 years in the wild. It is likely that rainbow snaked have a similar lifespan.

Behavior

Rainbow snakes live in water (natatorial) and also burrow on land (fossorial). Rainbow snakes are adept swimmers, as they often swim along streams or along the substrates of swamps. They are a nocturnal species. Once rainbow snakes have caught their prey, they will get out of the water with the prey in their mouths and swallow them head first. Rainbow snakes are found burrowed under logs, piles of debris, and in moving waters. When there is a drought, rainbow snakes emigrate to forests and mountains. Rainbow snakes are not known to hibernate because they have been captured during every month of the year. If captured and handled, they use their tails to stab the captors, but their tails are not sharp and do not pierce the skin. Male rainbow snakes fight each other to gain access to mating opportunities. Both males and females mate with multiple individuals per breeding season. Regarding predation and behaviors in capturing prey, not much is known about rainbow snakes. However, other members of the genus Farancia curl up with their head lowered beneath their coiled bodies and their tails in the air when a predator approaches. To catch prey, mud snakes ( Farancia abacura ) push their spear-like tails into the ground and push off to move forward. Mud snakes can smell their prey using their tongue and sense movement via ground vibrations. It's likely that rainbow snakes have similar mechanisms. Both rainbow snakes and mud snakes have spines on the end of their tails that they use to control prey that they have caught.

• Key Behaviors
• fossorial fossorial
• natatorial natatorial
• nocturnal nocturnal
• sedentary sedentary
• solitary solitary

Home Range

On average, rainbow snakes have been observed 44 m from the nearest wetland boundary (SD 44.91 m, range 0 to 117 m). Individuals have been observed up to 2000 m from the nearest body of water. They are not known to actively defend a territory.

Communication and Perception

Not much has been reported about tactile, acoustic, chemical, or electric communication in rainbow snakes. Other members of the genus Farancia curl up with their heads lowered beneath their coiled bodies and their tails in the air when a predator approaches. To catch prey, mud snakes ( Farancia abacura ) push their spear-like tails into the ground and push off to move forward. Both the rainbow snakes and mud snakes have spines on the end of thier tails that they use to control prey that they have caught. Mud snakes can sense the heat of a prey. Mud snakes use their tongue to smell any nearby prey and hear by sensing any ground vibrations. It's likely that rainbow snakes have a similar mechanism.

• Communication Channels
• visual visual
• chemical chemical

• Perception Channels
• visual visual
• infrared/heat infrared/heat
• vibrations vibrations
• chemical chemical

Food Habits

Juvenile rainbow snakes eat fish, salamanders, tadpoles, earthworms, mole salamander larvae Ambystoma talpoideum , and small frogs. Adult rainbow snakes only prey on American eels Anguilla rostrata . Rainbow snakes have been given the name eel moccasins because adults only eat American eels. Rainbow snakes eat their prey alive, swallowing them head first. Once rainbow snakes catch an eel, they climb out of the water and move onto shore or into exposed roots of a bald-cypress tree or underwater shrub to finish digesting their prey and to hide from predators.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • piscivore piscivore

• Animal Foods
• amphibians
• fish
• terrestrial worms

Predation

Rainbow snakes are preyed upon by many species. Rainbow snakes give warning signals by coiling their bodies and placing their heads down and raising their tails in the air. They are defenseless; they don't bite and their pointed tail does not inflict a wound. Predators of rainbow snakes include raccoons ( Procyon lotor ), Virginia opossums ( Didelphis virginiana ), red-tailed hawks ( Buteo jamaicensis ), and eastern indigo snakes ( Drymarchon couperi ).

Ecosystem Roles

No parasites have been reported for rainbow snakes.

Economic Importance for Humans: Positive

Rainbow snakes are purchased through the pet trade illegally. The harvest rates for rainbow snakes are very low. From 1990 to 1994, in Florida, only one rainbow snake was sold in the pet trade.

• Positive Impacts
• pet trade pet trade

Economic Importance for Humans: Negative

There are no negative economic impacts of rainbow snakes on humans.

• Negative Impacts
• injures humans
  • bites or stings

Conservation Status

Rainbow snakes are listed as a species of Least Concern on the IUCN Red List. They have no special status for US Federal List, State of Michigan or through CITES. Some rainbow snake populations have declined due to wetlands being drained, urbanization, and being collected for the pet trade. They can be affected by a snake fungal disease, Ophidiomyces ophiodiicola . No other major threats are known and no conservation efforts are currently in place for rainbow snakes.

Additional Links

Encyclopedia of Life

Contributors

Justin Wood (author), Radford University, Alex Atwood (editor), Radford University, Karen Powers (editor), Radford University, Joshua Turner (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

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