Crotalus oreganus
Silhouette: Bill Bouton (source photo) & T. Michael Keesey (vectorization) · PhyloPic
In 3 days ~70% in a week ~90%
Crotalus oreganus, commonly known as the Western rattlesnake or northern Pacific rattlesnake, is a venomous pit viper species found in western North America from the Baja California Peninsula to the southern interior of British Columbia.
The size of this species varies greatly, with some populations being stunted and others growing very large. The species also varies in size in relation to its migration routes as individuals with longer and more linear paths tend to have more mass. The C. oreganus is classified with 6 subspecies with 3 of them being present within the state of California.
This species, in its various forms, shows considerable ontogenetic variation. Juveniles usually have more or less distinct patterns, but these fade as the animals mature. The color of the iris often matches the ground color, which may be bronze, gold, or different shades of tan, pink, or gray.
The habitat and/or the substrate of the Crotalus oreganus determines their coloration. The color pattern of the typical form, C. o. oreganus, has... Wikipedia →
Recording0:29
Canada · 2023
© Julia Carr · iNaturalist · CC BY-NC 4.0
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Canada · 2021
© Leah Ramsay · iNaturalist · CC BY-NC 4.0
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Canada · 2026
© Nathan Earley · iNaturalist · CC BY-NC 4.0
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Sequoia and Kings Canyon National Parks | 🇺🇸 United States | |
| 2 | Zion National Park | 🇺🇸 United States | |
| 3 | Yosemite National Park | 🇺🇸 United States | |
| 4 | Grand Canyon National Park | 🇺🇸 United States | |
| 5 | Joshua Tree National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Sacramento | 🇺🇸 United States | |
| 2 | Tijuana | 🇲🇽 México | |
| 3 | San Diego | 🇺🇸 United States | |
| 4 | Los Angeles | 🇺🇸 United States | |
| 5 | Salt Lake City | 🇺🇸 United States | |
| 6 | San Francisco | 🇺🇸 United States |
| # | Zoo / Centre | Country | |
|---|---|---|---|
| 1 | San Diego Zoo | 🇺🇸 United States | |
| 2 | Living Desert Zoo and Gardens | 🇺🇸 United States | |
| 3 | Bronx Zoo | 🇺🇸 United States | |
| 4 | Los Angeles Zoo | 🇺🇸 United States | |
| 5 | Phoenix Zoo | 🇺🇸 United States | |
| 6 | Fresno Chaffee Zoo | 🇺🇸 United States | |
| 7 | Hogle Zoo | 🇺🇸 United States | |
| 8 | California Living Museum | 🇺🇸 United States | |
| 9 | Santa Barbara Zoo | 🇺🇸 United States | |
| 10 | Reptile Gardens | 🇺🇸 United States | |
| 11 | Sacramento Zoo | 🇺🇸 United States | |
| 12 | Turtle Bay Exploration Park | 🇺🇸 United States | |
| 13 | Staten Island Zoo | 🇺🇸 United States | |
| 14 | Orange County Zoo | 🇺🇸 United States | |
| 15 | Siam Serpentarium | 🇹🇭 Thailand | |
| 16 | Lindsay Wildlife Experience | 🇺🇸 United States | |
| 17 | The Reptile Zoo | 🇺🇸 United States | |
| 18 | CuriOdyssey | 🇺🇸 United States |
No species of the same family or order lives in Yosemite National Park, so these are its closest relatives here: other reptiles.
Possible
About 30% of wildlife watchers report a Western Rattlesnake sighting in Yosemite National Park on a given day, based on 179 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 3rd most-seen of the 17 reptiles we can rate there. Over three days the chance rises to about 70%, and over a week to about 90%, if each day is a fresh chance.
May to August
In those months about 40% of wildlife watchers report a Western Rattlesnake in Yosemite National Park on a given day, against under 5% in February–March and November–December, the lowest months. Those are among Yosemite National Park's driest months, with about 35 mm of rain a month against 220 mm in January.
Between 8 and 11 am
Across all the parks we cover, that three-hour window holds the most Western Rattlesnake sightings with a recorded time, and about 6 in 10 of them come between 6 am and 6 pm: it is seen both by day and at night.
3rd of 5
Of the 5 parks where we can rate Western Rattlesnake sightings, Yosemite National Park ranks 3rd at about 30%. The best odds are in Sequoia and Kings Canyon National Parks (United States, about 40%) and Zion National Park (United States, about 30%). All parks ranked.
GBIF citizen-science records
It is estimated from how often the Western Rattlesnake is recorded against all the reptiles logged in Yosemite National Park (179 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.
