Western Rat Snake

P. obsoletus

Last updated: May 23, 2022
Verified by: AZ Animals Staff
Image Credit Rusty Dodson/Shutterstock.com

Western rat snakes have special scales on their belly that help them climb up trees.

Western Rat Snake Scientific Classification

Kingdom
Animalia
Phylum
Chordata
Class
Reptilia
Order
Squamata
Family
Colubridae
Genus
Pantherophis
Scientific Name
P. obsoletus

Read our Complete Guide to Classification of Animals.

Western Rat Snake Conservation Status

Western Rat Snake Locations

Western Rat Snake Locations

Western Rat Snake Facts

Prey
Lizards, rats, mice, birds, squirrels, chipmunks
Main Prey
Rats, mice
Name Of Young
Hatchlings
Group Behavior
  • Solitary
Fun Fact
Western rat snakes have special scales on their belly that help them climb up trees.
Most Distinctive Feature
Adults have glossy black bodies that sometimes show faint patterns.
Other Name(s)
western rat snake, black rat snake, pilot black snake, black snake
Temperament
Docile
Litter Size
6-20
Habitat
Rocky hillsides, farmland, abandoned buildings, forested areas
Diet
Carnivore
Lifestyle
  • Diurnal
  • or Nocturnal Depending on Region and Season

Western Rat Snake Physical Characteristics

Color
  • Brown
  • Grey
  • Black
Skin Type
Scales
Lifespan
20 years

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View all of the Western Rat Snake images!



Western rat snakes are one of the longest snakes in North America; the longest one on record measured 111 inches. They are long, slender, non-venomous constrictors that are terrific climbers. These snakes are members of the Colubridae family and are closely related to king snakes.

They’re a wonderful natural pest control that will seek out mice, rats, squirrels, birds, and even bats to eat. Juveniles often feed on lizards and frogs but as they mature develop a taste for rodents.

Amazing Facts About Western Rat Snakes

  • The scales on their bellies flip up and grab onto surfaces which helps them climb to astounding heights.
  • For such a large snake, they’re quite mellow. Once you’re holding one it calms down pretty quickly.
  • Some people call them chicken snakes because they will get into a chicken coop and eat both eggs and chicks.
  • They’re closely related to king snakes, and some pet breeders have bred hybrids of the two species.

Where to Find Western Rat Snakes

Western rat snakes are adaptable animals that will make a home wherever they find food. They prefer forested areas with a water supply, but happily take up residence in old barns, abandoned buildings, and under homes. These snakes are partly arboreal, and will sometimes lay their eggs high up in the hollow of a tree. They’re excellent climbers that you may find 20 feet up a tree that has no lower branches.

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Their range extends west from the Mississippi River to central and northern Texas, and north to Iowa and Nebraska. Western rat snakes are long and slender, but powerful constrictors that suffocate their prey before swallowing it whole. These snakes sometimes reach 6 feet in length and darken as they mature; however, despite their size, they’re not aggressive at all.

They brumate beginning in October or November, finding a safe place to pass the colder months. as soon as the weather warms, western rat snakes become active again. Breeding takes place between April and June, the female lays her eggs in a secluded space about 4-6 weeks later. After 60-75 days the hatchlings emerge; these are excellent breeders, and females can lay up to 20 eggs at a time.

Western Rat Snake’s Scientific Name

This snake’s genus name, Pantherophis, means “Panther snake,” and it makes sense; the juveniles’ spotted pattern is reminiscent of panther, and as they develop their adult coloration the pattern is still somewhat visible on some individuals.



Types of Rat Snakes

With over 50 rat snake species occurring throughout the world, it’s often hard to keep track of them. Here are the species herpetologists know inhabit areas of the United States.

Bogertophis

Desert rat snakes occur in the Southwest United States into northern Mexico. There is a wide variety of habitats that Baja California rat snakes (Brosaliae) and Trans-Pecos rat snakes (B. subocularis) inhabit.

Pantherophis 

This genus holds most of the rat snake species in the United States. This includes the gray rat snake (P. spiloides), Eastern rat snake (P. alleghaniensis), Baird’s rat snake (P. bairdi), Great plains rat snake (P. emoryi), Eastern fox snake (P. gloydi), Western fox snake (P. ramspotti), Corn snake (P. guttatus), western (or black) rat snake (P. obsoletus), and Slowinski’s corn snake (P. slowinskii).

A few species in Pantherophis have subspecies; while others, such as the gray rat snake and western rat snake possibly hybridize near the Mississippi River. Genetically, many rat snakes are similar enough to also mate with king snakes, and a few pet breeders have done this to create new morphs.

Western Rat Snakes: Population and Conservation

There aren’t any estimates of population, however, biologists believe they have a stable population in most areas. The IUCN Redlist considers them “Least Concern.” Their main threats, after the mistaken identity issues and collection for the pet trade, are predation from other animals. Birds of prey (red-tailed hawks even hunt the larger snakes), coyotes, foxes, minks, and snakes all make being a western rat snake a dangerous occupation.

That said, in some states where they are less common, such as Minnesota, they’re listed as a species of special concern. They have only been documented in a couple of southeastern counties in the state; so in 2013, after many studies, the state of Minnesota classified it as a threatened species.

Identifying Western Rat Snakes: Appearance & Description

This is a fairly large snake, although it’s not very thick. Western rat snakes can reach 6 feet long, and the record was set by a wild-caught snake that measured over 8 feet (101 inches). Most snakes average from 4-6 feet. Young snakes have a bright, high-contrast pattern with a grey background and dark brown blotches on the back and sides. The blotches on their backs have slight points at the corners, and those on the sides are more irregular in shape. They darken rapidly as they mature, and many of these snakes become almost solid black on their backs but retain lighter colors with black spots on their bellies. Most of them have a white chin, but not all.

Western Rat Snakes Pictures and Videos

Western rat snake
Western rat snakes darken as they mature lose most of the pattern on their heads and bodies.

iStock.com/Naja Shots

adult western rat snake in defensive posture
Western rat snake showing ‘S’ shape in a defensive posture.

Rusty Dodson/Shutterstock.com

Young Western Rat snake
Western rat snakes come in many colors but darken with age and lose some of the patterns.

Joe Farah/Shutterstock.com

closeup of western rat snake
Many western rat snakes have a white chin.

Rusty Dodson/Shutterstock.com

How Dangerous are Western Rat Snakes

These snakes aren’t dangerous; however, if you corner one it may freeze and hope you don’t see it, bite, release an awful smelling musk, rattle its tail, or coil up and strike. Western rat snakes have several defenses against threats and will use any tool at their disposal to escape injury.

  • At the first sign of a threat, a western rat snake may stiffen and kink up, giving its body a zig-zag shape; it may also freeze in place, hoping you won’t see it.
  • If that fails, then it might coil up, form its neck into an ‘S’ shape, and rattle its tail. Some believe the tail rattle is mimicking rattlesnakes, but other disagree because the same behavior occurs in many snakes around the world where there are no rattlesnakes.
  • At this point, if you are still bugging this snake, it will bite. Fortunately it won’t be too bad; remember, it doesn’t have any venom.
  • Its last resort (not that biting isn’t bad enough), is to release musk from its vent, or cloaca. This stuff stinks. It doesn’t wash off well, and sort of sticks to you until you scrub a lot.

All that said, it’s not a dangerous snake, and is very helpful to people. They keep rodents (and other critters) from taking over the world.

Western Rat Snake Behavior and Humans

Western rat snakes aren’t aggressive, and they won’t come after you. Most often, these snakes try to escape. Even as they’re being harassed by someone they’re looking for an escape route. While human encroachment can be a problem for them, by and large, they have adapted to life in the suburbs.

However, many of these snakes are killed because of their pattern; people mistake them for rattlesnakes or copperheads and panic. In addition to confusing their pattern with venomous snakes, western rat snakes, like many other non-venomous snakes, can spread their head out to look more diamond-shaped like a pit viper; however, from above the snake’s head, its eyes are easy to see. A pit viper’s eyes are very difficult to see from above its head.

These constrictors perform a vital service, and while they are often found in some unexpected places, they’re harmless.

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About the Author

Gail is a musician, author, and artist with more ideas than time. She loves learning about all things in the natural world. Her upcoming book, Pebble Worms and Fast Walkers is filled with all the random bits that kids love! She lives in North Texas with her husband, twin sons, dogs, cat, two red-eared sliders, and two ball pythons.

Western Rat Snake FAQs (Frequently Asked Questions) 

Are western rat snakes venomous?

No, like all rat snakes, western rat snakes are non-venomous.

How do western rat snakes hunt?

These snakes are active diurnal and spend most of their day actively seeking a meal. They are constrictors, so when they bite their prey, they also wrap tightly around it to suffocate it before swallowing.

Where do western rat snakes live?

Western rat snakes inhabit forests and meadows in the central United States. It prefers heavily wooded areas but is adaptable.

Are western rat snakes aggressive?

They’re not aggressive, but they will defend themselves.

If you corner one, it puts on a display that includes rattling its tail to mimic a rattlesnake, coiling and forming its head and neck into an ‘S’ shape; finally, if you pick it up, it may bite and release musk, a foul-smelling substance it spreads around with its tail.

What do western rat snakes eat?

These are opportunistic feeders and will eat a wide variety of prey animals. Their favorites are warm-blooded prey, such as rats, mice, and birds.

What's the difference between a black racer and black rat snake?

The main differences between a black racer and a black rat snake are their markings and sizes. Black rat snakes are larger than black racers, and black racers prefer to run away while black rat snakes hold their ground.

Sources
  1. Reptile Database, Available here: https://reptile-database.reptarium.cz/
  2. IUCN Redlist, Available here: https://www.iucnredlist.org/species/90069553/90069569
  3. Western Rat Snake | Seneca Park Zoo, Available here: https://senecaparkzoo.org/animal-pages/western-rat-snake/
  4. Western Ratsnake | Missouri Department of Conservation, Available here: https://mdc.mo.gov/discover-nature/field-guide/western-ratsnake

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