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Rattlesnake

Dusky Rattlesnake

Venomous

Crotalus triseriatus

Dusky Rattlesnake
Crotalus triseriatus, © Hugo Juárez
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6 photographs of the Dusky Rattlesnake. © Hugo Juárez.

The Dusky Rattlesnake (Crotalus triseriatus) is a venomous snake in the Viperidae family, recorded in 2 countries.

If you are bitten

Rattlesnake bites are medically serious. Expect intense pain, rapid swelling, and bruising. Stay calm, keep the bitten limb still and roughly level with the heart, remove rings and tight clothing, and get to an emergency room immediately. Do NOT apply a tourniquet, cut the wound, apply ice, or try to suck out venom. Call Poison Control at 1-800-222-1222 or 911 in the US, or your local emergency number. (Source: CDC.)

Also called
Rattlesnake
Family
Viperidae
Size
Typically 2–5 ft; some species exceed 6 ft.
Habitat
Deserts, rocky outcrops, grasslands, and woodland edges, depending on species.
Behavior
Ambush predators that buzz the tail as a warning; mostly active in warm months and often crepuscular in summer heat.
Identify
Heavy body, broad triangular head, vertical (cat-like) pupils, and a segmented keratin rattle at the tail tip.
Danger
high

About the Dusky Rattlesnake

Common names: Mexican dusky rattlesnake, dusky rattlesnake

Crotalus triseriatus is a venomous pit viper species found in Mexico. Two subspecies are currently recognized, including the nominate subspecies described here.

Description

Adult male specimens of C. triseriatus commonly grow to a total length (including tail) greater than 60 cm (24 in), with females somewhat smaller. The maximum recorded total length is 68.3 cm (26.9 in).

Geographic range

The species C. triseriatus is found in Mexico, along the southern edge of the Mexican Plateau in the highlands of the Transverse Volcanic Cordillera, including the states of Jalisco, México, Michoacán, Morelos, Nayarit, Puebla, Tlaxcala, and Veracruz. The type locality given by Wagler in 1830 is "Mexico". A restriction to "Alvarez, San Luis Potosí, Mexico" was proposed by H.M. Smith and Taylor (1950).

Habitat

Crotalus triseriatus occurs in pine-oak forest, boreal forest, coniferous forest and, bunchgrass grasslands. On Volcán Orizaba, it is found at very high altitudes. There, the snow line comes down to about 4,572 m (15,000 ft), while green plants can be found up to 4,573 m (15,000 ft): the species has been found within this zone. However, it is most common at 2,700 to 3,350 metres (8,860 to 10,990 ft) in elevation.

Conservation status

The species C. triseriatus is classified as Least Concern on the IUCN Red List of Threatened Species. Species are listed as such due to their wide distribution, presumed large population, or because they are unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend was stable when assessed in 2007.

Feeding

Prey reportedly found in stomachs of C. triseriatus include a frog, a murid rodent (Neotomodon alstoni), lizards, other small mammals, crickets, and salamanders.

Venom

Bite symptoms from C. triseriatus are reported to include intense pain, swelling, faintness, and cold perspiration.

Subspecies

Etymology

The subspecific name, armstrongi, is in honor of American herpetologist Barry L. Armstrong.

Taxonomy

In the relatively recent past, two additional subspecies were described:

C. t. anahuacus Gloyd, 1940 - currently regarded as a junior synonym of C. t. triseriatus

C. t. quadrangularis Harris & Simmons, 1978 - currently regarded as a junior synonym of C. aquilus

Adapted from Wikipedia, available under CC BY-SA.

Frequently asked: Dusky Rattlesnake

Is the Dusky Rattlesnake venomous?
Yes. The Dusky Rattlesnake (Crotalus triseriatus) is venomous and belongs to the Viperidae family (rattlesnake). Its bite is considered high risk to people. Treat any bite as a medical emergency.
Is the Dusky Rattlesnake poisonous?
Snakes are venomous, not poisonous. "Poisonous" means harmful to eat or touch; "venomous" means injecting toxins through a bite. The Dusky Rattlesnake is venomous, delivering venom through a bite.
Is the Dusky Rattlesnake dangerous?
Rattlesnake bites are medically serious. Expect intense pain, rapid swelling, and bruising. Stay calm, keep the bitten limb still and roughly level with the heart, remove rings and tight clothing, and get to an emergency room immediately. Do NOT apply a tourniquet, cut the wound, apply ice, or try to suck out venom. Call Poison Control at 1-800-222-1222 or 911 in the US, or your local emergency number. (Source: CDC.)
Where does the Dusky Rattlesnake live?
The Dusky Rattlesnake has verified records in 2 countries, including Mexico, United States of America. See the distribution section below for its full range.
How do I identify the Dusky Rattlesnake?
Heavy body, broad triangular head, vertical (cat-like) pupils, and a segmented keratin rattle at the tail tip.
How big does the Dusky Rattlesnake get?
Typically 2–5 ft; some species exceed 6 ft.
What does the Dusky Rattlesnake eat?
Prey reportedly found in stomachs of C. triseriatus include a frog, a murid rodent (Neotomodon alstoni), lizards, other small mammals, crickets, and salamanders.
Why is it called the Dusky Rattlesnake?
The subspecific name, armstrongi, is in honor of American herpetologist Barry L. Armstrong.

If you are bitten by the Dusky Rattlesnake

A venomous snakebite is a medical emergency. Call your local emergency number immediately. In the US, dial 911 or Poison Control at 1-800-222-1222.

Do

  • Get away from the snake and stay calm. Most bites worsen when people panic or try again to handle the snake.
  • Call 911 or Poison Control (1-800-222-1222) right away. Antivenom works best when given early.
  • Note the time of the bite and, from a safe distance, the snake's color and pattern, a phone photo is enough. Do not chase it.
  • Keep the bitten limb still and at roughly heart level. Sit or lie down and limit movement.
  • Remove rings, watches, and tight clothing near the bite before swelling starts.
  • Gently wash the bite with soap and water and cover it with a clean, dry dressing.

Do not

  • Do not cut the wound or try to suck out the venom.
  • Do not apply a tourniquet or ice.
  • Do not drink alcohol or caffeine.
  • Do not take aspirin or ibuprofen, they can worsen bleeding. Acetaminophen is safer for pain.
  • Do not try to catch or kill the snake. A dead snake can still bite by reflex.

First-aid guidance adapted from the U.S. Centers for Disease Control and Prevention (CDC NIOSH), Venomous Snakes. Educational only; always follow the instructions of emergency responders.

Where it is found

MexicoUnited States of America

Snakes it is confused with

More Viperidae snakes

Classification

How scientists group this snake, from the broadest category down to the exact species. Each step narrows to its closest relatives.

OrderThe broad group of scaled reptiles: all snakes and lizards
Squamata
FamilyA group of related snakes that share key traits
Viperidae
GenusA close-knit group of very similar species
Crotalus
SpeciesThis exact snake, named in the two-part scientific name
Crotalus triseriatus

Keep learning

Distribution from GBIF & iNaturalist. Venom status per CDC. Background: Wikipedia. Informational only. Never handle a snake to identify it.