Bullsnake
A big, harmless snake that fakes being a rattlesnake — hissing, flattening its head, and shaking its tail in dry grass — to talk its way out of trouble.
Bullsnake at a glance
Pituophis catenifer sayi pit-yoo-OH-fiss kuh-TEN-ih-fer SAY-eye
- Type
- Reptile · snakes
- Diet
- Carnivore
- Size
- It is the largest reptile in several of these parks, sometimes reaching over 5 feet — about the height of a tall adult lying down.
- Lifespan
- Around 12 to 15 years in the wild.
- Conservation
- Least concern
Eats mice, ground squirrels, pocket gophers, rabbits, bird eggs
It hunts by scent through rodent burrows and grasslands, then constricts its prey — squeezing until it stops breathing — before swallowing it whole.
Should you worry?
Not dangerous at all — it has no venom. Its whole act (hissing, flattened head, shaking tail) is a bluff to make predators think twice, and people sometimes kill it by mistake, thinking it's a rattlesnake. It's safe to watch from a few feet away; leave it alone and let it pass.
Slam the brakes: something thick and patterned is coiled in the middle of the gravel road, head flattened, hissing hard enough to hear through a rolled-up window. Every instinct says rattlesnake. It isn’t. It’s a bullsnake, the biggest reptile in several of these parks, running a bluff it has no real weapon to back up.
The performance is the whole point. A bullsnake forces air past a flap of cartilage in its throat to make a hiss loud enough to pass for a rattle, flattens its head into something blockier and more snake-villain-shaped, and shakes its bare tail against dry grass to fake the buzz it has no rattle to actually make. None of it is backed by venom — it has none. The only real risk in the encounter is the bullsnake’s: drivers and hikers who fall for the act sometimes kill it on the spot, certain they’ve just avoided a rattlesnake.
Underground is where it does its real work, tracking mice and pocket gophers by scent straight into their own burrows and squeezing them still before swallowing them whole. On the surface, though, it survives mostly on nerve. Let the bluff finish, let it flatten back out and slide off into the grass, and the loudest snake in the park has done exactly what it came to do.
Did you know?
- A bullsnake has no rattle and no venom, but it can hiss, flatten its head, and shake its tail in dead grass well enough to fool people into thinking it's a rattlesnake.
- It is the largest reptile at Great Sand Dunes and one of the largest at Yellowstone, sometimes topping 5 feet long.
- It hunts mostly underground, following rodents into their own burrows and squeezing them before swallowing them whole.
Common questions
Are bullsnakes venomous? Do they bite?
No, bullsnakes have no venom at all. They may bite if grabbed or cornered, like almost any wild animal would, but the bite carries no poison — the real danger is people mistaking one for a rattlesnake and hurting it.
Why does a bullsnake sound like a rattlesnake?
It hisses hard through its throat and shakes its tail against dry grass or leaves on purpose, copying a rattlesnake's warning sound to scare predators off, even though it has no rattle.
How do you tell a bullsnake from a rattlesnake?
A bullsnake has a narrow tail that tapers to a point with no rattle, round pupils, and no heat-sensing pit between the eye and nose — a rattlesnake has a wide, segmented rattle and a blockier head.
What do bullsnakes eat?
Mostly rodents like mice, gophers, and ground squirrels, plus the occasional bird egg, all swallowed whole after being squeezed still.
What eats a bullsnake?
Bullsnakes are a kind of gopher snake. For the species as a whole, kit foxes, red-tailed hawks, and coyotes are the most common predators. Other foxes, hawks, and large kingsnakes probably eat them too.