@jencmars Good post! As it's nesting season in the Northern hemisphere it could be a fledgling too. As long as they're in a relatively safe spot, you should observe from a distance for about an hour, if their parents are still around and feeding them. If this is the case, everything is fine. Except if it's a swift. Swifts on the ground are ALWAYS in distress.
Whether fledgling or adult bird: Please DO NOT put a water bowl in the box. And refrain from putting water in its beak.
jencmars