Western Black-tailed Rattlesnake
Crotalus molossus
- KingdomAnimalia (Animals)
- PhylumChordata (Chordates)
- ClassSquamata
- FamilyViperidae (Vipers)
- GenusCrotalus (Rattlesnakes)
- SpeciesCrotalus molossus (Western Black-tailed Rattlesnake)
About the Western Black-tailed Rattlesnake
The black-tailed rattlesnake (Crotalus molossus) is a venomous pit viper species found in the southwestern United States and Mexico. Four subspecies are currently recognized, including the nominate subspecies described here.
A 2012 revision showed that eastern populations from Texas and central and eastern New Mexico form a distinct species separate from C. molossus: Crotalus ornatus Hallowell 1854. Alternate common names are green rattler, and Northern black-tailed rattlesnake.
This medium-sized species averages from 76 to 107 cm (30 to 42 in) in length. Large specimens are usually not much more than 100 cm (39 in) long, although lengths of 125.0 cm (49.2 in) (Gloyd, 1940), 125.7 cm (49.5 in) (Klauber, 1972), and 129.5 cm (51.0 in) (Shaw & Campbell, 1974) have been reported. The females tend to be larger than the males.
They range in color from yellows and olive greens to browns and black. As their name implies, one of their most distinguishing features is, despite variations in body color, entirely black tail scales. Often, this rattlesnake has a black band across its eyes extending diagonally down to the corners of its mouth... Wikipedia →
Global Distribution
Where this species is recorded worldwide. Restricted to human observations from 2019 onwards — the same kind of record and the same period the probabilities on this page are built from, so collar-tracking studies, camera-trap arrays and museum specimens are excluded. Around Santa Rosa that removes 5,924 GPS fixes from a handful of tagged jaguars.
where this species is recorded (GBIF density — it tracks where observers go, not how likely a sighting is) · parks where it occurs — tap a pin for the sighting probability there
Parks Where Found
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Saguaro National Park | 🇺🇸 United States | |
| 2 | Reserva de la Biosfera Mariposa Monarca | 🇲🇽 Mexico | |
| 3 | Grand Canyon National Park | 🇺🇸 United States |
Quick answers
What are the chances of seeing a Western Black-tailed Rattlesnake in Saguaro National Park?
About 10% of wildlife watchers report a Western Black-tailed Rattlesnake sighting in Saguaro National Park, based on 180 verified sightings from GBIF citizen-science data.
When is the best time to see Western Black-tailed Rattlesnake in Saguaro National Park?
August has the highest sighting rate for Western Black-tailed Rattlesnake in Saguaro National Park in our monthly data.