Bogertophis subocularis
Silhouette: Alex Slavenko · PhyloPic
In 3 days ~60% in a week ~90%
The Trans-Pecos rat snake or Davis Mountain rat snake (Bogertophis subocularis), is a species of medium to large, nonvenomous rat snake in the family Colubridae. Bogertophis subocularis is endemic to the Chihuahuan Desert.
The Trans-Pecos rat snake is found in the Mexican states of Chihuahua, Coahuila, Durango, and Nuevo León, and its range extends northward into Texas and New Mexico in the United States. B. subocularis has a row of small scales (suboculars) between the lower border of the eye and the upper labials. Coloration is yellow to tan dorsally with a series of black, or dark brown, H-shaped markings. The eye is large and prominent, light-colored with a contrasting round black pupil. The tongue is pink. The dorsal scales are in 31-35 rows at midbody. The ventrals number 260-277; the subcaudals number 69-79.
Adults are usually 36-54 inches (90–137 cm) in total length (including tail). The record total length is 66 inches (168 cm). The Trans-Pecos rat snake's habitat consists of desert flats and brushy slopes, and rocky outcrops where it dens. B. subocularis feeds on small vertebrates. A nocturnal... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Big Bend National Park | 🇺🇸 United States | |
| 2 | Guadalupe Mountains National Park | 🇺🇸 United States |
| # | Zoo / Centre | Country | |
|---|---|---|---|
| 1 | Cameron Park Zoo | 🇺🇸 United States | |
| 2 | Texas Zoo | 🇺🇸 United States | |
| 3 | Children's Aquarium at Fair Park | 🇺🇸 United States |
Possible
About 30% of wildlife watchers report a Trans-pecos Ratsnake sighting in Big Bend National Park on a given day, based on 84 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 9th most-seen of the 48 reptiles we can rate there. Over three days the chance rises to about 60%, and over a week to about 90%, if each day is a fresh chance.
July
In that month about 50% of wildlife watchers report a Trans-pecos Ratsnake in Big Bend National Park on a given day, against under 5% in February and November, the lowest months.
Between 9 pm and midnight
Across all the parks we cover, that three-hour window holds the most Trans-pecos Ratsnake sightings with a recorded time, and about 9 in 10 of them come between 6 pm and 6 am: it is mostly seen at night.
Yes
Of the 2 parks where we can rate Trans-pecos Ratsnake sightings, Big Bend National Park has the highest daily chance: about 30%. Next come Guadalupe Mountains National Park (United States, about 10%).
Same family: Colubridae
The closest relatives of the Trans-pecos Ratsnake that you can see in Big Bend National Park (family Colubridae, Colubrid Snakes) are Coachwhip (about 20%), Long-nosed Snake (about 20%) and Gopher Snake (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Trans-pecos Ratsnake is recorded against all the reptiles logged in Big Bend National Park (84 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.
