Pretty Nashville Warblers
I also started finding Nashville Warblers on May 5 and have seen 2-4 each day so far. This is a species that is not terribly common in southern parts of Colorado and per ebird only seen in fall in Fremont County.
What fun, I saw a number of these just a few weeks ago in the Texas Hill Country where they were migrating through and now get to them in Colorado as they move north to their breeding areas. SeEtta