Reptiles
Black-Tailed Rattlesnake
Crotalus molossus · also called blacktail rattlesnake
A hiker steps within a few feet of a black-tailed rattlesnake coiled quietly among rocks that match its own colouration almost exactly, and rather than rattling or striking, the snake simply stays still, relying on a calm temperament and effective camouflage that most other rattlesnakes are considerably less willing to trust.
Overview
The black-tailed rattlesnake, Crotalus molossus, is a venomous ambush predator native to desert scrub, rocky canyon, and mountain woodland habitat across the southwestern United States and much of Mexico. Its solid black tail, notably calm temperament, and tolerance for a wide range of elevations make it one of the more behaviourally distinctive and widely encountered rattlesnakes in the region.
A rattlesnake that would rather not be noticed at all
While many rattlesnakes rely on a loud warning display when threatened, the black-tailed rattlesnake more often bets on simply not being seen in the first place, trusting camouflage and stillness over the dramatic defensive performance many people expect from a rattlesnake.
Status
Least Concern — widespread and stable across suitable desert and mountain habitat throughout the southwestern United States and much of Mexico.
Black-Tailed Rattlesnake: common questions
Why is the black-tailed rattlesnake considered calmer than other rattlesnakes?
This species is widely observed to rely more heavily on remaining motionless and camouflaged when a potential threat approaches, rather than immediately rattling or striking the way some more defensively reactive rattlesnake species tend to, a behavioural tendency that has earned it a reputation among herpetologists and hikers as one of the more even-tempered rattlesnake species to encounter.
Why does the black-tailed rattlesnake have such variable colouration?
This species shows considerable colour variation across its broad range, generally matching the specific rock and soil tones of its local habitat, an adaptation that likely improves camouflage effectiveness for an ambush predator that depends on staying visually concealed from both prey and potential threats across a wide variety of desert and mountain terrain.
What elevation range does the black-tailed rattlesnake live in?
This species tolerates an unusually broad range of elevations compared with some other rattlesnake species, found from lower desert scrub habitat up into higher mountain woodland, a flexibility that has allowed it to occupy a wider variety of terrain types across the southwestern United States and Mexico.
How does the black-tailed rattlesnake hunt?
This species is primarily an ambush hunter, remaining motionless in a concealed position that takes advantage of its region-matched camouflage, and striking with venom at rodents, rabbits, or birds that come within range, rather than actively pursuing prey across open ground the way some more mobile hunting snakes do.