Prairie Rattlesnake (Crotalus viridis)

Subspecies

This snake has two recognized subspecies.

• Hopi rattlesnake (Crotalus viridis nuntius)
• Prairie rattlesnake (Crotalus viridis viridis)

Description

Size

Commonly, this species grows to more than 3.3ft (100 cm) in length. The maximum recorded size is 4.97ft (151.5 cm). Montana has some specimens exceeding 3.9ft (120 cm), with the species reaching its maximum size in this state.

Color and Appearance

The snakes are usually lightly colored in shades of brown. The dorsal pattern often has patches of dark brown. A color band may be present at the back of the eye. It has a distinctive triangular-shaped head with pit sensory organs on either side. Its identifying feature is the presence of 3 or more, usually 4, internasal scales, two of which are in contact with the rostral.

Are They Dangerous to Humans 

The species typically bite when threatened or injured. It has powerful venom, 20-55% of which is used in a single bite. The venom has both hemotoxic (muscle and tissue destroying) and neurotoxic (brain and nervous system damaging) effects. But before striking, it warns its attacker by rapidly vibrating its tail, producing a rasping sound unique to rattlesnakes.

The bite can cause swelling, severe pain, and bruising. There can also be nausea, difficulty in breathing, and disturbed vision. Severe cases can result in low blood pressure, shock, internal bleeding, and even death. So, medical attention needs to be sought soon after the snakebite.

Prairie Rattlesnakes at a Glance

Distribution

In North America, prairie rattlesnakes are found over much of the Great Plains, some intermontane valleys, and the eastern foothills of the Rocky Mountains, from southwestern Canada through the US to northern Mexico. In Canada, they live in Saskatchewan and Alberta; in the United States in most of Montana (where it is one of 10 snake species and the only venomous one), eastern Idaho, North Dakota, South Dakota, Nebraska, Wyoming, Colorado, Oklahoma, Kansas, Texas, New Mexico, extreme western Iowa, extreme southeastern Utah, northeastern Arizona; and in Mexico in northwestern Chihuahua and northern Coahuila. Its vertical range is from 330 ft (100 m) near the Rio Grande to over 9,104 ft (2,775 m) altitude in Wyoming.

Habitat

It mainly occurs in somewhat rocky regions, with the outcrops acting as den sites. It also occupies the burrows of other animals. The prairie rattlesnake seems to prefer dry areas with moderate vegetation coverage.

The pit viper prefers sinuosity while migrating, even in human-dominated environments, as it increases its chances of survival and ensures a better body condition during and post-migration.

Lifespan

The average lifespan of the pit viper is 16-20 years.

Predators

The prairie rattlesnake is preyed upon by raptors, carnivorous mammals, and king snakes.

Diet

The species prefers small mammals, like ground squirrels, rabbits, mice, rats and prairie dogs, and ground-nesting birds as its food. They occasionally eat reptiles, amphibians, and even other snakes.

Since they have poor eyesight, their heat-sensitive pits and forked tongue, capable of picking up airborne scents, are helpful adaptations for catching prey.

Reproduction

Viviparous (gives birth to live young)

The breeding season sees the males competing for the females, but the latter may not breed every year. In late summer or early fall, they give birth to 1-25 young in a brood, with an average of 4-12. The average number of young in a brood varies greatly with the environmental conditions and food availability. The venomous juveniles are 22-28 cm long and don’t need parental care. They reach sexual maturity at 3 years of age.

Similar Species

Western Diamondback Rattlesnake

Prairie rattlesnakes are thinner and longer than western diamondbacks, Crotalus atrox, that have flatter faces and larger patches. Plus, the latter has an even ratio of black and white stripes on the tail, near the rattle, while the ratio of white to black for the former is 2:1.

Timber Rattlesnake

Timber rattlesnakes, Crotalus horridus, have distinct black chevron-shaped patterns all along their backs. Their tails are velvet-black at the end with a light-colored rattle.

Bullsnake

A bullsnake, Pituophis catenifer, has round pupils, while the prairie rattlesnake has vertical ones. Plus, the former lacks heat-sensing pits above its nostrils, and the tail rattle.