Rattlesnake or Kingsnake?
Massasauga—note the distinctive head shape and eye stripes

As the weather warms up, some of us find ourselves scanning the ground as we walk, keeping our eyes peeled for unwelcome visitors.

Unfortunately, identifying a rattlesnake at a glance is not always easy because it has a harmless look-alike—the prairie kingsnake. The most obvious difference between the two is the tail. Rattlesnakes have rattles; kingsnakes do not.

But what if you can’t get a good look at the tail? Young rattlesnakes have tiny rattles that are hard to see or hear. And what about a snake with its head in a pathway and its tail in tall grass? Or what about a kingsnake that is giving you its best rattlesnake imitation, coiling up and vibrating its tail against dead leaves to produce a warning noise?

Fortunately there are a few more identifying characteristics that you can use:

Rattlesnake or Kingsnake?
Prairie rattlesnake
  • Head shape. Rattlesnakes are pit vipers, which means that they have “pits” on the sides of their heads, used to detect heat from their prey. Kingsnakes do not have pits, giving their heads the more rounded shape of other snakes.
  • Head markings. Kingsnakes typically have a small, relatively thin line behind their eyes and a patch of dark color shaped something like an arrowhead on top of their heads. Rattlesnakes typically have thick stripes of color running back from their eyes, but their head markings are usually otherwise unremarkable.
  • Pupil shape. Okay, if you’re close enough to the snake’s head to see the shape of its pupils, you’re too close! Still, it is true that kingsnakes have rounded pupils, while rattlesnakes have diamond-shaped pupils, almost like a cat’s slits.
  • Back markings. A reddish-brown stripe down the back identifies the snake as a timber rattlesnake. However, it cannot be used to distinguish between the prairie kingsnake, the massasauga, and the prairie rattlesnake.
  • Belly markings. A light, unmarked belly is characteristic of the prairie rattlesnake and the timber rattlesnake. However, both the harmless kingsnake and the venomous massasauga rattlesnake can show markings on the belly, although the latter’s pattern is sometimes less distinct.
  • Range. There is some degree of overlap between the ranges of the prairie kingsnake and its venomous look-alikes. A prairie kingsnake can be found nearly every part of Kansas except for the northern half of the High Plains. A questionable snake in that area is almost certainly a prairie rattlesnake. The timber rattlesnake is restricted to the eastern third of the state. The massasauga can be found in almost any part of Kansas as far as the High Plains, where it still inhabits river valleys.
Rattlesnake or Kingsnake?
Timber rattlesnake—note the pupil shape and the brown line on the back

Of course, caution is the best policy when it comes to suspicious-looking snakes; and even though a kingsnake is not venomous, it still bites. So keep your eyes open!

Helpful Resources

Prairie Kingsnake
Western Massasauga
Prairie Rattlesnake
Timber Rattlesnake
Photos and more information from the Kansas Herpetofaunal Atlas.