The incubating bird was more visible today. Is it possible that she is "tenting" a chick that has hatched?. No other adult in sight from about 12 noon to 1:00 PM. Visit
http://blog.rosyfinch.comHere, the adult (female?) is peering down underneath her-- is she rearranging eggs or tending to a hatchling? Her head and sometimes part of her back and tail were visible the entire period of observation.