Colias alexandra
In 3 days ~30% in a week ~50%
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 Rocky Mountain National Park on a given day, based on 48 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 32nd most-seen of the 191 insects we can rate there. Over three days the chance rises to about 30%, and over a week to about 50%, if each day is a fresh chance.
July
In that month about 20% of wildlife watchers report a Queen Alexandra’s Sulphur in Rocky Mountain National Park on a given day, against under 5% in September to May, the lowest months. That is one of Rocky Mountain National Park's wettest months, with about 95 mm of rain against 40 mm in September.
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.
Yes
Of the 2 parks where we can rate Queen Alexandra’s Sulphur sightings, Rocky Mountain National Park has the highest daily chance: about 10%. Next come Yellowstone National Park (United States, about 10%).
Same genus: Colias
The closest relatives of the Queen Alexandra’s Sulphur that you can see in Rocky Mountain National Park (genus Colias, Clouded Yellows) are Mead's Sulphur (about 10%), Colias scudderi (about 10%) and Clouded Sulphur (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Queen Alexandra’s Sulphur is recorded against all the insects logged in Rocky Mountain National Park (48 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.
