Crotalus morulus
Silhouette: Bill Bouton (source photo) & T. Michael Keesey (vectorization) · PhyloPic
In 3 days ~20% in a week ~50%
Crotalus morulus, or the Tamaulipan rock rattlesnake, is a species of rattlesnake from Mexico, closely related to and previously considered a subspecies of Crotalus lepidus. The name morulus comes from the Latin word morus for mulberry in reference to their mottled patterns. As with all rattlesnakes, it is venomous.
As juveniles, Crotalus morulus has a dark pattern with black blotches dorsally on a grey base, the dark colours blending between the patterns. Adults are also grey with dark-brown blotches. They are distinguished from Crotalus lepidus by this dark colouration and higher number of blotches.
Their rattle is also known to be fluorescent, although more dull in adults than neonates. Crotalus morulus is known to be ovoviviparous. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cumbres de Monterrey National Park | 🇲🇽 Mexico |
More parks will be added in future updates.
| # | Zoo / Centre | Country | |
|---|---|---|---|
| 1 | Abilene Zoological Gardens | 🇺🇸 United States | |
| 2 | Saint Louis Zoo | 🇺🇸 United States | |
| 3 | Fort Worth Zoo | 🇺🇸 United States | |
| 4 | Houston Zoo | 🇺🇸 United States | |
| 5 | The Abilene Zoo | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Tamaulipan Rock Rattlesnake sighting in Cumbres de Monterrey National Park on a given day, based on 24 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 17th most-seen of the 43 reptiles we can rate there. Over three days the chance rises to about 20%, and over a week to about 50%, if each day is a fresh chance.
July
In that month about 20% of wildlife watchers report a Tamaulipan Rock Rattlesnake in Cumbres de Monterrey National Park on a given day, against under 5% in February and November, the lowest months.
Between 10 am and 1 pm
Across all the parks we cover, that three-hour window holds the most Tamaulipan Rock Rattlesnake sightings with a recorded time, and about 7 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Only Cumbres de Monterrey National Park, in our data
Cumbres de Monterrey National Park is the only park on Wallace's Line with enough records to rate Tamaulipan Rock Rattlesnake sightings: about 10% of wildlife watchers there report one on a given day.
Same genus: Crotalus
The closest relatives of the Tamaulipan Rock Rattlesnake that you can see in Cumbres de Monterrey National Park (genus Crotalus, Rattlesnakes) are Totonacan Rattlesnake (about 10%), Eastern Black-tailed Rattlesnake (about 10%) and Rock Rattlesnake (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Tamaulipan Rock Rattlesnake is recorded against all the reptiles logged in Cumbres de Monterrey National Park (24 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
