Note on spring Baird's that their backs are mottled, not neatly patterned or as colorful as White-rumped. The feathering is pointed, unlike the neatly rounded feathers on an immature. Also note the feathers are fresh and unworn.

The upper mandible is straight while there is a curve in the lower mandible and the bill is all black. The markings on the breast are blurred and not neatly lined up as those on the White-rumped. There is usually a flush of buff across the upper breast but it is not present on all spring migrants.