Colias behrii
In 3 days ~40% in a week ~70%
Colias behrii, the Behr's sulphur or Sierra green sulfur, is a butterfly in the family Pieridae. It is endemic to California's Sierra Nevada from Tuolumne County south to Tulare County. The wingspan is 35–42 mm (1.4–1.7 in). Adults are on wing from July to August. They feed on flower nectar.
The larvae feed on Vaccinium species and Gentiana newberryi. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Yosemite National Park | 🇺🇸 United States | |
| 2 | Sequoia and Kings Canyon National Parks | 🇺🇸 United States |
Possible
About 20% of wildlife watchers report a Sierra Sulphur sighting in Yosemite National Park on a given day, based on 141 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 16th most-seen of the 227 insects we can rate there. Over three days the chance rises to about 40%, and over a week to about 70%, if each day is a fresh chance.
July
In that month about 40% of wildlife watchers report a Sierra Sulphur in Yosemite National Park on a given day, against under 5% in November to June, the lowest months. That is one of Yosemite National Park's driest months, with about 25 mm of rain against 220 mm in January.
Between 11 am and 2 pm
Across all the parks we cover, that three-hour window holds the most Sierra Sulphur sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
Yes
Of the 2 parks where we can rate Sierra Sulphur sightings, Yosemite National Park has the highest daily chance: about 20%. Next come Sequoia and Kings Canyon National Parks (United States, under 5%).
GBIF citizen-science records
It is estimated from how often the Sierra Sulphur is recorded against all the insects logged in Yosemite National Park (141 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.
