Colias alexandra
In 3 days ~20% in a week ~40%
Colias alexandra, the Queen Alexandra's sulphur, Alexandra sulphur, or ultraviolet sulfur, is a butterfly in the family Pieridae found in western North America. Its range includes Alaska to the Northwest Territories and south to Arizona and New Mexico. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Rocky Mountain National Park | 🇺🇸 United States | |
| 2 | Yellowstone National Park | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Queen Alexandra’s Sulphur sighting in Yellowstone National Park on a given day, based on 16 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 72nd most-seen of the 160 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
June to August
In those months about 10% of wildlife watchers report a Queen Alexandra’s Sulphur in Yellowstone National Park on a given day, against under 5% in September to May, the lowest months.
Between 11 am and 2 pm
Across all the parks we cover, that three-hour window holds the most Queen Alexandra’s Sulphur sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
Among the best
Of the 2 parks where we can rate Queen Alexandra’s Sulphur sightings, Yellowstone National Park ranks 2nd at about 10%, level with the leaders once rounded. The best odds are in Rocky Mountain National Park (United States, about 10%).
GBIF citizen-science records
It is estimated from how often the Queen Alexandra’s Sulphur is recorded against all the insects logged in Yellowstone National Park (16 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.
