CO birders,
According to eBird, there has only been 1 other Laughing Gull found in Colorado in the last 5 years!
Checklist comments by the finder George Ho say that the Merlin Photo ID function made the identification, and while the app does not have 100% accuracy and should not be relied upon by itself in identification, this is an example of Merlin accurately picking out a rarity! In the photos, notice how the outer half of the primary feathers (or roughy outer 1/3 of the wing) are almost solidly black, whereas the similar and more common Franklin's Gull would show only a small band of black near the wingtips, bordered by white. Folded, the primaries appear entirely black, whereas in Franklin's you would see large white primary tips.
See photos in the checklist below: