Snakes with black and white patterns are a widespread and visually striking group. Their contrasting coloration serves various biological functions and can be found across numerous species globally. Understanding these snakes, from identification to the ecological roles of their coloration, offers valuable insight into their natural history.
Identifying Black and White Snake Species
Many non-venomous snake species display black and white patterns, often featuring rings, bands, or blotches.
The California Kingsnake (Lampropeltis californiae) commonly exhibits alternating bands of black or brown and white or cream. These snakes typically reach lengths of 2.5 to 3.5 feet and inhabit diverse environments across the western United States and northern Mexico, including woodlands, grasslands, deserts, and suburban areas.
Milk Snakes (Lampropeltis triangulum) are another group with many subspecies displaying black, white, and red bands or blotches. The Eastern Milksnake (Lampropeltis triangulum triangulum) typically has reddish-brown blotches edged in black on a tan or gray background, with a black and white checkerboard belly. These snakes average 2 to 2.5 feet in length and are found in varied habitats from open woodlands to agricultural fields throughout the eastern United States. The Pueblan Milk Snake (Lampropeltis triangulum campbelli), often confused with coral snakes, features red, black, and white band patterns.
Eastern Kingsnakes (Lampropeltis getula) are generally glossy black with white or yellowish chain-like bands that cross the back and connect along the sides. Their size can range from 36 to 48 inches. These snakes are common throughout the eastern United States, thriving in diverse habitats such as hardwood forests, pine forests, swamps, and farmlands. The Black Kingsnake (Lampropeltis nigra), a subspecies, is typically a stocky black snake with small yellowish spots and a black and white checkered belly. Adult Black Kingsnakes can reach up to 4 feet in length and are found in forests, agricultural lands, and suburban areas.
Rat Snakes, such as the Eastern Rat Snake (Pantherophis obsoletus), are non-venomous and average 3.5 to 7 feet. While adults are often solid black with a light-colored belly and white chin and throat, younger snakes may exhibit blotches or patterns that fade with maturity. These adaptable snakes inhabit a broad range across eastern and central North America, found in forests, woodlands, grasslands, and even suburban environments.
Distinguishing Venomous from Harmless Black and White Snakes
Differentiating venomous black and white snakes from harmless ones is a safety concern, especially with species that mimic dangerous counterparts. General visual cues like head shape and pupil shape are not always reliable for identification. For instance, many venomous pit vipers have triangular heads and elliptical pupils. However, some non-venomous snakes can flatten their heads to appear triangular, and venomous coral snakes have round pupils and slender heads.
The classic rhyme “red touch yellow, kill a fellow; red touch black, venom lack” is often used to distinguish venomous Coral Snakes from non-venomous Milk Snakes and King Snakes in North America. This rhyme applies to New World Coral Snakes, which typically have red bands touching yellow bands. Harmless mimics like Milk Snakes usually have red bands touching black bands. While widely known, this rhyme is not universally reliable, especially for coral snake species found outside of North America. Coral snakes are generally small and reclusive, but their neurotoxic venom can cause paralysis.
The Role of Black and White Coloration
The black and white patterns observed in snakes serve several biological purposes, providing evolutionary advantages.
One primary function is camouflage, helping snakes blend into their surroundings to avoid predators or ambush prey. Disruptive coloration, where patterns break up the outline of the snake’s body, makes it harder for predators to detect the snake in varied environments. For example, the alternating colors of a Zebra Snake help it blend into rocky or sandy areas.
Aposematism, or warning coloration, is another role for black and white patterns, particularly when combined with bright colors like red or yellow. Venomous species, such as Coral Snakes, display these vivid patterns to signal their toxicity to potential predators. This visual warning benefits both the predator and the snake.
Batesian mimicry is closely related to aposematism, where harmless snakes imitate the warning coloration of venomous species. The non-venomous California Mountain Kingsnake (Lampropeltis zonata), with its red, black, and white bands, mimics the venomous coral snake. This resemblance deters predators who have learned to avoid the dangerous model, offering protection to the harmless mimic.
What to Do When You Encounter a Black and White Snake
Encountering any snake, regardless of its coloration, requires a cautious approach to ensure safety. Observe the snake from a safe distance. Do not attempt to handle, provoke, or harm the snake. Most snakes will try to move away if given space.
While identification can be helpful, prioritizing safety is paramount. If a snake is in an undesirable location, such as inside a home or a high-traffic area, contact local animal control or wildlife authorities. These professionals are equipped to handle snakes safely and humanely. Avoid trying to remove the snake yourself, as this increases the risk of a bite.