Nerodia rhombifer
Silhouette: Beth Reinke · PhyloPic
In 3 days ~10% in a week ~30%
Nerodia rhombifer, commonly known as the diamondback water snake, is a species of nonvenomous natricine colubrid endemic to the central United States and northern Mexico. There are three recognized subspecies of N. rhombifer, including the nominotypical subspecies.
The species was first described as Tropidonotus rhombifer by Edward Hallowell in 1852. The diamondback water snake is predominantly brown, dark brown, or dark olive green in color, with a black net-like pattern along the back, with each spot being vaguely diamond-shaped. Dark vertical bars and lighter coloring are often present down the sides of the snake. In typical counter-colored fashion, the underside is generally a yellow or lighter brown color, often with black blotching.
The dorsal scales are heavily keeled, giving the snake a rough texture. The dorsal scales are arranged in 25 or 27 rows at midbody. There are usually 3 postoculars. Adult males have multiple papillae (tubercles) on the under surface of the chin, which are not found on any other species of snake in the United States.
Nerodia rhombifer grows to an average total length (including tail) of 76–122 cm (30... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cumbres de Monterrey National Park | 🇲🇽 Mexico |
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | San Antonio | 🇺🇸 United States | |
| 2 | Houston | 🇺🇸 United States | |
| 3 | Dallas | 🇺🇸 United States | |
| 4 | Austin | 🇺🇸 United States | |
| 5 | Monterrey | 🇲🇽 México |
| # | Zoo / Centre | Country | |
|---|---|---|---|
| 1 | San Antonio Zoo | 🇺🇸 United States | |
| 2 | Leningrad Zoo | 🇷🇺 Russia | |
| 3 | Gran Acuario de Mazatlán "Mar de Cortés" | 🇲🇽 Mexico | |
| 4 | Oklahoma Aquarium | 🇺🇸 United States |
Rare
Under 5% of wildlife watchers report a Diamondback Watersnake sighting in Cumbres de Monterrey National Park on a given day, based on 10 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 40th most-seen of the 43 reptiles we can rate there. Over three days the chance rises to about 10%, and over a week to about 30%, if each day is a fresh chance.
March, May and November
In those months about 10% of wildlife watchers report a Diamondback Watersnake in Cumbres de Monterrey National Park on a given day, against under 5% in April, June–October and December–February, the lowest months.
Between 9 pm and midnight
Across all the parks we cover, that three-hour window holds the most Diamondback Watersnake sightings with a recorded time, and about 6 in 10 of them come between 6 pm and 6 am: it is seen both by day and at night.
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 Diamondback Watersnake sightings: under 5% of wildlife watchers there report one on a given day.
Same family: Colubridae
The closest relatives of the Diamondback Watersnake that you can see in Cumbres de Monterrey National Park (family Colubridae, Colubrid Snakes) are Northern Cat-eyed Snake (about 10%), Baird's Ratsnake (about 10%) and Great Plains Ratsnake (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Diamondback Watersnake is recorded against all the reptiles logged in Cumbres de Monterrey National Park (10 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.
