Black Racer vs. Rat Snake: How to Tell Them Apart in Tennessee

Middle Tennessee has two large, solid black snakes that are frequently confused with each other — and with venomous species. The black racer (Coluber constrictor) and the black rat snake (Pantherophis alleghaniensis) are both common, both non-venomous, and both capable of reaching impressive sizes. But they are quite different animals with different behaviors, habitats, and habits.

Here is how to tell them apart — and why it matters.

Both species are harmless to humans. So why does the distinction matter?

Because their behavior is completely different. A rat snake in your attic is following a rodent problem and will stay as long as the food source remains. A black racer in your yard is almost certainly just passing through and will be gone on its own. Understanding which snake you have tells you whether you need to act.

Because misidentification leads to unnecessary alarm. Both species are sometimes mistaken for venomous snakes — particularly timber rattlesnakes and cottonmouths. Knowing these two harmless species well reduces the chance of a dangerous misidentification.

This is the most reliable field identification feature and can be assessed from a safe distance.

Black racer: Slender and whip-like. The body is thin and uniform in diameter for most of its length, tapering to a very fine tail. A 4-foot racer looks almost impossibly slender. The overall impression is of a fast, lightweight animal.

Black rat snake: Heavier and more robust. The body is thicker in proportion to its length, with a slightly flattened, somewhat rectangular cross-section (rather than perfectly round). A 4-foot rat snake looks substantially more solid than a racer of the same length.

Black racer: Smooth scales with a high gloss. In sunlight, a black racer has a distinctly shiny, almost iridescent appearance. The smooth scales reflect light uniformly.

Black rat snake: Slightly keeled scales — each scale has a faint ridge running down its center. This gives the rat snake a duller, more matte appearance compared to the racer's gloss. In sunlight, a rat snake looks less shiny than a racer.

This difference is visible at close range and is one of the most reliable distinguishing features.

Black racer: Lives up to its name. The black racer is one of the fastest snakes in North America, capable of moving at speeds up to 4 miles per hour — fast enough that it appears to blur when fleeing. When you approach a black racer, it will almost always flee immediately and rapidly. It rarely holds its ground.

Black rat snake: Moves slowly and deliberately. Rat snakes are patient, methodical hunters that spend long periods motionless. When approached, they often freeze rather than flee. When they do move, it is at a fraction of the speed of a racer.

Speed is one of the easiest ways to distinguish these two species in the field. If the snake disappeared before you could get a good look at it, it was almost certainly a racer.

Black racer: Primary defense is flight. When cornered and unable to flee, racers will bite aggressively and repeatedly — they are among the more bite-prone harmless snakes in Tennessee. They may also vibrate their tails in dry leaves (mimicking a rattlesnake) and release musk. But their first and preferred response is always to run.

Black rat snake: Holds its ground more readily than a racer. When threatened, rat snakes display a distinctive defensive posture: the body kinks into a series of angular bends, the tail vibrates rapidly, and the snake may strike. This kinking behavior is highly characteristic of rat snakes and is rarely seen in racers.

Black racer: The belly is typically white or pale gray, relatively uniform in color, transitioning abruptly from the black dorsal surface.

Black rat snake: The belly is white or cream with dark gray or black checkering or mottling. The pattern is more complex than the racer's relatively plain belly.

This difference requires getting a look at the underside of the snake, which is not always practical in the field.

Black racer: Prefers open habitats — fields, meadows, forest edges, brushy areas, and roadsides. Racers are active, wide-ranging hunters that cover a lot of ground. They are less associated with wooded areas than rat snakes and are rarely found inside structures.

Black rat snake: More strongly associated with wooded areas, forest edges, and structures. Rat snakes are the snake most likely to be found in attics, crawlspaces, barns, and outbuildings. Their climbing ability gives them access to elevated spaces that racers rarely reach.

Practical implication: If you find a large black snake inside your home or in your attic, it is almost certainly a rat snake. If you find one crossing an open field or road, it could be either species — but the racer is more likely in open habitat.

Both species look dramatically different as juveniles compared to adults — and both juveniles are frequently mistaken for copperheads.

Juvenile black racer: Gray or light brown with a series of dark brown blotches down the back. The blotches are more irregular and less distinctly hourglass-shaped than a copperhead's bands. The head is narrower and more oval than a copperhead's triangular head.

Juvenile black rat snake: Also gray-brown with dark blotches, very similar to the juvenile racer. The juvenile rat snake tends to have slightly more rectangular blotches and a slightly heavier body than a juvenile racer of the same length.

Both juvenile species darken progressively as they mature, reaching the solid black adult coloration by 3–4 years of age.

Important: If you find a small, blotched snake in late summer and are unsure whether it is a juvenile rat snake, juvenile racer, or copperhead — call our identification hotline before handling it. Juvenile copperheads are venomous and do occur in Middle Tennessee.

Both the black racer and the black rat snake are sometimes mistaken for venomous species. Here is how to rule out the dangerous ones:

vs. Timber Rattlesnake: Timber rattlesnakes have a rattle at the tail tip, elliptical pupils, and a very broad triangular head. Adult timber rattlesnakes also have a chevron pattern that is visible even on dark individuals. Neither the racer nor the rat snake has a rattle.

vs. Cottonmouth: Cottonmouths are heavy-bodied, semi-aquatic, and found near water. They have a broad triangular head, elliptical pupils, and display a white mouth interior when threatened. Both the racer and rat snake have round pupils and do not display a white mouth.

vs. Copperhead: Adult copperheads are never solid black — they always have the distinctive hourglass banding pattern on a copper-brown background. Juvenile copperheads are blotched, but the hourglass pattern is visible and the head is distinctly triangular.

Black racer in the yard: Almost certainly no action needed. Racers are transient hunters that cover large territories. The snake you see today will likely be gone tomorrow. Leave it alone.

Black rat snake in the yard: Also generally no action needed, unless it is in a location where children or pets could encounter it. A rat snake in the yard is doing useful work controlling rodents.

Black rat snake in your home, attic, or crawlspace: This warrants professional removal and an exclusion inspection. The snake got in through a gap, and that gap needs to be found and sealed. Call Nashville Snake Removal at (615) 613-5992.

Either species and you cannot confirm the identification: Call our 24-hour identification hotline. Send a photo or describe what you are seeing, and we will tell you exactly what you are dealing with.

If you need to make a quick field identification:

1. Did it disappear before you could get a good look? → Black racer
2. Is it holding its ground and kinking its body? → Black rat snake
3. Does it look shiny and whip-thin? → Black racer
4. Does it look heavier and more matte? → Black rat snake
5. Is it in your attic or crawlspace? → Almost certainly a black rat snake

Both are harmless. Neither requires emergency action. But if you are unsure — or if the snake is inside your home — call us.

Nashville Snake Removal serves Davidson, Williamson, Sumner, Wilson, Robertson, Dickson, and Stewart counties. Same-day service available. Call (615) 613-5992.