Northern Black-tailed Rattlesnake
Crotalus molossus
A robust, calm-tempered rattlesnake of rocky desert and mountain terrain, easily recognized by its uniformly dark tail.
- Venomous?
- Venomous
- Adult length
- 0.9-1.2 m (3-4 ft)
- Range
- Southwestern USA (Arizona, New Mexico, Texas) and northern Mexico
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Overview
The Northern Black-tailed Rattlesnake is a large-bodied pit viper found across the mountainous and rocky landscapes of the American Southwest and northern Mexico. It is one of the more reluctant-to-strike rattlesnakes, often relying on camouflage and its rattle to avoid confrontation.
Color varies regionally from olive-yellow to nearly black, but the solid black tail (lacking distinct bands) gives the species its common name and is a reliable field mark.
How to identify it
- Background color olive, yellow-green, or gray with dark diamond or blotch pattern down the back
- Tail uniformly black or very dark, without the alternating light/dark bands seen in most other rattlesnakes
- Head broad and triangular with vertical pupils
- Heavy-bodied with keeled scales giving a rough texture
- Distinguished from Western Diamond-backed Rattlesnake by lack of banded tail
Habitat & range
Found in rocky canyons, boulder-strewn slopes, desert grasslands, and pine-oak woodlands, typically from 900-2,700 m elevation. Often seen basking near rock outcrops that provide cover and thermoregulation sites.
Behavior, diet & reproduction
Primarily active at dusk and night in warm months, though it may bask during the day in cooler seasons. Known for a docile disposition, frequently allowing close approach before rattling. Feeds on rodents, rabbits, and birds. Live-bears young in late summer.
Frequently asked questions
Is the Northern Black-tailed Rattlesnake dangerous?
Yes, it is venomous, though it is generally considered one of the calmer, less defensive rattlesnake species.
How can I tell it apart from other rattlesnakes?
Its solid black tail without banding, contrasting with a lighter body, is the clearest identifying feature.
Where does it live?
It inhabits rocky, mountainous terrain across the southwestern United States and northern Mexico.
What does it eat?
Mainly small mammals like rodents and rabbits, occasionally birds.
Northern Black-tailed Rattlesnake guides
In-depth guides for identifying and understanding Northern Black-tailed Rattlesnake.
