The folk belief that “black snakes” kill copperheads is one of the most persistent pieces of snake lore in the eastern United States, and it is partly true but widely misunderstood. The confusion stems from a case of mistaken identity: the large, dark-colored snake most people call a “black snake” is usually the black rat snake, which does not routinely hunt or kill copperheads. The snake that genuinely does prey on copperheads and other venomous species is the eastern kingsnake, a different animal that also happens to be dark. Sorting out which species does what changes the practical advice for anyone who encounters either snake on their property.
Which Snake Are You Actually Looking At?
In the southeastern and mid-Atlantic states, three common nonvenomous species are dark enough to earn the label “black snake” from a casual observer. The black rat snake (now classified as Pantherophis alleghaniensis in the East, with the western black rat snake split off as Pantherophis obsoletus) is the one most people encounter. It can reach six feet or more, is an excellent climber, and feeds primarily on rodents, birds, and eggs. It is not a snake specialist. The North American racer, often called the black racer (Coluber constrictor), is leaner, faster, and more aggressive when cornered, but its diet runs toward insects, frogs, lizards, and small rodents. It will occasionally eat a very small snake, but it is not built for taking on an adult copperhead.
Then there is the eastern kingsnake (Lampropeltis getula), which in many populations is jet-black or very dark brown with faint chain-like banding. This is the species behind the legend. Kingsnakes are ophiophagous, meaning they eat other snakes as a regular part of their diet, including venomous pit vipers like copperheads, cottonmouths, and rattlesnakes. When someone tells you a “black snake killed a copperhead in the yard,” odds are decent it was a kingsnake. The trouble is that from ten feet away, a large black rat snake and a large eastern kingsnake can look almost identical to an untrained eye, and the two species share much of the same range.
How Kingsnakes Overpower Other Snakes
Kingsnakes are constrictors, and they are remarkably good at it. Research comparing the constriction performance of kingsnakes to that of rat snakes found that kingsnakes squeeze with substantially higher pressures. Peak constriction pressures in kingsnakes ranged from roughly 5 to 42 kPa, while rat snakes topped out around 3 to 24 kPa. The study also tested escape performance and found the prey snakes were not unusually bad at getting away; kingsnakes simply outmuscle them.1Journal of Experimental Biology. The king of snakes: performance and morphology of intraguild predators (Lampropeltis) and their prey (Pantherophis) That pressure advantage is how a kingsnake subdues a copperhead that might otherwise bite and envenomate a less equipped predator.
Once the prey is restrained, swallowing another snake presents its own engineering problem. Snakes are long, and a prey snake can easily be close to the predator’s own body length. Kingsnakes solve this by forcing the prey’s spinal column into tight bends during swallowing, effectively accordion-folding it so it fits inside the digestive tract. Dissections of kingsnakes shortly after feeding show the prey snake compressed into waves inside the predator’s stretched esophagus and stomach.2Zoology. How snakes eat snakes: the biomechanical challenges of ophiophagy for the California kingsnake, Lampropeltis getula californiae Kingsnakes almost always swallow their prey head-first, which makes the folding process smoother and keeps the prey’s scales from catching against the inside of the throat.
Venom Resistance and Why It Matters
Killing a copperhead means getting close enough to be bitten, and copperheads do bite defensively. What protects kingsnakes is a well-documented natural resistance to pit viper venom. Their blood serum contains proteins that neutralize key components of crotalid venom, giving them a buffer that most other nonvenomous snakes lack. This is not total immunity; a large enough dose from a large enough rattlesnake can still harm a kingsnake. But copperheads are small-to-medium-sized vipers with relatively mild venom compared to many of their relatives.3Toxicon. A comparison of biological and chemical properties of three North American (Crotalidae) snake venoms A kingsnake’s tolerance is generally more than sufficient to brush off a copperhead bite and finish the job.
Black rat snakes and racers lack this venom resistance. If a rat snake and a copperhead got into a genuine fight, the copperhead’s venom could injure or kill the rat snake. This is one of the practical reasons black rat snakes do not function as copperhead predators even though they are powerful constrictors in their own right. They simply have no biochemical defense against the bite.
Copperheads Know a Kingsnake When They Smell One
One of the more fascinating pieces of evidence that kingsnakes are a real threat to copperheads comes from behavioral studies. Pit vipers, including copperheads, recognize kingsnakes chemically, likely through tongue-flicking detection of skin lipids and other chemical cues. When a copperhead or rattlesnake detects a kingsnake, it does not adopt its usual strike-and-retreat defensive posture. Instead, it displays a distinctive set of behaviors: hiding its head beneath its coils, thrashing its body violently, and performing an unusual maneuver called “body bridging,” where it raises a loop of its body off the ground and swipes it toward the kingsnake.4Brain, Behavior and Evolution. Chemical Recognition of Kingsnakes by Crotalines: Effects of Size on the Ophiophage Defensive Response Body bridging appears to be a way of slapping the predator away without exposing the vulnerable head.
These behaviors are specific to kingsnake encounters. A copperhead confronted by a hawk, a human, or another nonvenomous snake will typically coil, rattle its tail in leaf litter, or strike. The fact that venomous snakes have evolved a completely separate behavioral repertoire specifically for kingsnake encounters tells you how significant a predatory threat kingsnakes are. It also means that copperheads are at least somewhat aware of the danger and actively try to avoid kingsnake territory, though “avoid” is a strong word for animals that navigate by scent and do not maintain territories in the way mammals do.
Do Black Rat Snakes Keep Copperheads Away Indirectly?
This is where the folk wisdom gets more complicated. Even though black rat snakes do not kill copperheads, some people argue they still reduce copperhead numbers by competing for the same food and shelter. The logic goes like this: if a rat snake is living in your barn eating all the mice, there are fewer mice to attract a copperhead.
There is a grain of ecological sense to this, but the evidence for meaningful competitive exclusion between these two species is thin. Copperheads and black rat snakes do overlap in range across much of the eastern United States and share some habitat preferences, with copperheads favoring forested areas with abundant cover.5PubMed. Landscape-level influences of terrestrial snake occupancy within the southeastern United States But copperheads are ambush predators that sit and wait for prey to come within striking distance, while rat snakes are active foragers that climb and explore. Their hunting strategies are different enough that both can easily coexist in the same patch of woods without one meaningfully displacing the other. In practice, the presence of a rat snake in your yard does not create a copperhead-free zone.
The most honest assessment is that black rat snakes are harmless, beneficial rodent controllers that happen to be dark-colored, and they deserve protection for those reasons alone. But if your specific concern is keeping copperheads away, a rat snake is not a reliable bodyguard.
Why the Myth Persists
The “black snake kills copperheads” belief has unusual staying power because it combines a true observation with a false identification. People really do find dead copperheads near large dark snakes. In areas where eastern kingsnakes are common, this does happen. But the observer rarely identifies the predator to species level, and “black snake” becomes the catch-all label. The story enters local folklore, gets repeated at hardware stores and family reunions, and eventually the black rat snake inherits a reputation it did not earn.
There is also an emotional dimension. Copperheads are the most common venomous snake across much of the eastern US, and people living in copperhead country feel understandably nervous about them. The idea that a friendly, nonvenomous snake is out there doing pest control on the dangerous ones is deeply appealing. It gives people a reason to tolerate large snakes in their yards, which is ecologically good even if the stated reason is wrong. Conservation biologists have sometimes leaned into the myth for this reason: if believing that rat snakes kill copperheads stops someone from killing a rat snake, the ecosystem benefits regardless of whether the belief is accurate.
The downside of the myth is that it sometimes leads people to release or relocate kingsnakes into their yards as copperhead deterrents. This is generally a bad idea. Relocated snakes often die from stress, exposure, or inability to find food in unfamiliar territory. They also do not “patrol” an area the way a guard dog would. A kingsnake in your yard eats whatever opportunity presents, and if it wanders off the next day, you have accomplished nothing except stressing the snake.
What Actually Reduces Copperhead Encounters
If your real goal is to see fewer copperheads around your home, the evidence-based approach is habitat modification, not biological warfare. Copperheads are ambush predators that depend on cover. They favor leaf litter, rock piles, stacked firewood, overgrown brush, and old outbuildings where rodents congregate. Removing or reorganizing these features reduces the odds that a copperhead will set up shop nearby.
- Clear debris: Brush piles, leaf accumulation, and stacked lumber next to foundations give copperheads both hiding spots and hunting grounds. Moving these away from high-traffic areas is the single most effective step.
- Control rodents: Mice and voles are a copperhead’s primary food. If your property has a rodent problem, you have a copperhead attractant. Ironically, this is where black rat snakes actually help, not by fighting copperheads but by eating the mice that draw them in.
- Trim vegetation: Low ground cover and unmowed grass along walkways and foundations provide copperheads with the concealment they prefer. Keeping a mowed buffer around structures makes the area less inviting.
- Seal entry points: Copperheads enter garages, crawl spaces, and basements through surprisingly small gaps. Weather-stripping doors and screening foundation vents blocks access.
None of these steps guarantee a copperhead-free property, especially in heavily forested areas where the surrounding habitat is ideal for them. But they are far more reliable than hoping a kingsnake moves in.
The Decline of Eastern Kingsnakes
An aspect of this topic that rarely comes up in backyard conversations is that eastern kingsnake populations have declined in parts of their range over the past several decades, particularly in the southeastern United States. The causes are not fully resolved, but habitat fragmentation, road mortality, and fire ant predation on eggs and hatchlings are all suspected contributors. In some areas where kingsnakes were once abundant, they have become genuinely uncommon.
This matters for the copperhead question because it means the natural predatory check that kingsnakes once provided has weakened in those regions. Whether kingsnake decline has contributed to copperhead population increases is an open question that researchers have not definitively answered. Copperhead populations appear stable to increasing in many suburban and exurban areas, but that could just as easily be explained by the expansion of favorable edge habitat where subdivisions meet forest, which creates ideal conditions for both copperheads and the rodents they eat.
What is clear is that kingsnakes are the real article when it comes to controlling venomous snake populations through predation, and losing them from a landscape removes one of the few natural enemies adult copperheads face. Hawks, owls, and certain mammals will take copperheads opportunistically, but none of them specialize in snake-eating the way kingsnakes do. The constriction advantage, the venom resistance, and the head-first swallowing technique make kingsnakes uniquely adapted for the job. For anyone fortunate enough to have kingsnakes on their property, leaving them undisturbed is the single best thing you can do for local snake ecology.