Coral snakes, with their vibrant and distinctive color patterns, are fascinating yet elusive members of the Elapidae family, which also includes cobras and mambas. Found primarily in the Americas and parts of Asia, these snakes are known for their potent venom and secretive lifestyles. This article delves into the dietary habits of the eastern coral snake (Micrurus fulvius), exploring what they eat, how they hunt, and what eats them.
Identification and Distribution
Coral snakes are recognized by their slender bodies adorned with red, yellow, and black rings. In the United States, a helpful mnemonic distinguishes venomous coral snakes from nonvenomous mimics like the scarlet kingsnake and scarlet snake: "Red next to yellow, kill a fellow; red next to black, friend of Jack." However, it's important to note that this rhyme is only applicable in North America.
The eastern coral snake, Micrurus fulvius, is distributed east of the Mississippi River, ranging from southeastern North Carolina through Florida and westward to parts of Alabama, Mississippi, and southeastern Louisiana. They inhabit sandy areas and spend a significant amount of time underground, making them a rare sight.
Habitat and Behavior
Eastern coral snakes favor dry, open, or brushy habitats with loose soils, including hardwood forests and pine flatwoods. They are semifossorial creatures, often found buried in soil, leaf litter, logs, or stumps. Like other reptiles in the Coastal Plain, they may also utilize gopher tortoise burrows.
These snakes are secretive and primarily diurnal, meaning they are active during the day. Sightings at night are rare. When discovered, coral snakes typically attempt to escape. If cornered, they may exhibit defensive behaviors such as hiding their head beneath their body coils, mimicking their head with their tail, erratic movements, and even feigning death.
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Primary Prey: Reptiles
The eastern coral snake's diet consists almost entirely of burrowing reptiles. This includes small lizards like skinks, glass lizards, and fence lizards, as well as small snakes such as green snakes, ringneck snakes, crowned snakes, and even other coral snakes.
Lizards
Lizards form a significant portion of the coral snake's diet. These snakes hunt by thrusting their heads randomly into leaf litter and debris, seizing prey and chewing vigorously to envenomate them.
Snakes
Coral snakes are known to prey on various snake species, including other coral snakes, showcasing cannibalistic behavior. This is a common trait among snakes, where smaller or weaker individuals may become a food source for larger ones.
Secondary Prey: Occasionally Frogs, Rodents, and Birds
While reptiles are their primary food source, eastern coral snakes may occasionally consume frogs, small rodents, and nesting birds. These instances are less common, as their hunting strategies and habitat preferences are more aligned with reptilian prey.
Frogs
Frogs are an infrequent part of the coral snake's diet. They may be consumed opportunistically if encountered during their hunts.
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Rodents and Birds
Similarly, small rodents and nesting birds are rarely eaten. These instances typically occur when the snake stumbles upon them in their environment.
Hunting Techniques
Coral snakes employ unique hunting methods that differ from those of pit vipers. Lacking the heat-sensing abilities of snakes like copperheads or rattlesnakes, coral snakes rely on encountering prey through random head thrusts into leaf litter and debris.
Envenomation
Once prey is located, the coral snake bites and holds on, injecting its potent neurotoxic venom. The small size of their mouth limits the size of prey they can consume and the amount of venom they can deliver in a single bite. Unlike pit vipers with larger, hollow fangs, coral snakes have smaller fangs and a less effective envenomation mechanism. The venom causes rapid paralysis and respiratory failure in the prey.
Cannibalism
Coral snakes are cannibalistic. Part of what makes coral snakes unique is their hunting methods. The first step for a hungry coral snake is finding food! Unlike pit vipers, coral snakes don’t have the ability to heat-sense their way to prey. Thankfully, the prey that coral snakes prefer often lives nearby. Once they are close enough to strike, the next step is to bite. Coral snakes are extremely venomous, although they aren’t great at delivering that venom to their prey. The main reason coral snakes can’t deliver a lot of venom is the design of their mouth; it’s extremely small! The size of their mouth not only limits how hard they can bite, but the types of prey they can eat. Instead of biting and releasing, coral snakes bite their prey instead and hold on. This behavior is common in snakes that eat snakes, and probably has more to do with not allowing escape than anything else. However, this behavior also likely gave rise to the myth that coral snakes have to ”chew” to envenomate.
Predators of Coral Snakes
Despite their venomous nature, coral snakes are preyed upon by various animals. Diurnal predaceous birds like American kestrels, hawks, and shrikes are known to depredate them. Snake-eating snakes, including other coral snakes, and bullfrogs are also known predators.
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Birds of Prey
Birds of prey are among the most significant predators of coral snakes. These birds have excellent eyesight and can spot snakes from above, making them vulnerable to aerial attacks.
Other Snakes and Bullfrogs
Snake-eating snakes and bullfrogs also pose a threat to coral snakes. These predators are opportunistic and will consume coral snakes if the opportunity arises.
Conservation Status and Threats
The eastern coral snake is considered rare and possibly threatened, with few recent observations indicating a decline in Alabama. The most serious threat to their populations is habitat destruction, particularly the loss of the longleaf pine-turkey oak-wiregrass community. Fire ant predation may also contribute to a decline in prey species.
Habitat Destruction
Habitat destruction is a primary concern for coral snake populations. The alteration and fragmentation of their natural habitats reduce their ability to find food, shelter, and mates.
Fire Ant Predation
The introduction and spread of fire ants may negatively impact coral snakes by reducing the availability of their prey. Fire ants are known to prey on various small animals, potentially disrupting the ecological balance.
Additional Information
Micrurus fulvius is usually less than 80 cm (31 in) in total length (tail included). The maximum reported total lengths are 121.8 cm (48.0 in) for a specimen in Florida (Neill, 1958) and 129.5 cm (51.0 in) (Roze, 1996). The dorsal scales are smooth, and are in 15 rows at midbody. The ventral scales number 197-217 in males and 219-233 in females. The color pattern consists of a series of rings that encircle the body: wide red and black rings separated by narrow yellow rings. The head is black from the rostral scale to just behind the eyes. This snake commonly has a black snout as well as black eyes and then a yellow band on the back half of their head behind the eyes. The red rings are usually speckled with black.
The bright coloration is likely aposematic, meaning that it is associated with a danger (venom) to predators. People who live in its natural range are often taught a folk rhyme as children such as: "Red next to black, safe from attack; red next to yellow, you're a dead fellow," or "Red touching black, friend of Jack; red touching yellow, you're a dead fellow", or simply "red and yellow kill a fellow". These rhymes are useful in teaching children to distinguish king snakes (Lampropeltis ssp.), which are considered helpful predators of vermin such as rats and mice, from the venomous coral snake, which should only be handled by an experienced biologist or herpetologist.
The current range of the eastern coral snake is predicted to expand as a result of climate change. The ranges of both M. fulvius and M. tener are expected to change with the climate warming.