I went out in slightly better light tonight and two owls were on the ground. Thanks to Brian (really, THANK YOU, Brian!), I have come to the conclusion that I likely mis-IDed the owls in west Longmont. They are bulky and seem too large for Barn Owls. If they're Great-Horneds, it was a very late brood because they are pale and have no visible horns. There was no sign of an adult. The only vocalization is a high-pitched screech.
I'll be watching these guys and trying to get out even earlier (they were out and on the ground at 8:30 tonight) to try and get a full-front view. So far, I have only seen one from the back during the day (pale, pale, no horns) and profiles in the dark. I will keep you updated, one way or the other.
Very sorry if I mis-IDed them. Sometimes, wishful thinking clouds one's judgement.
Kat Bradley-Bennett
Longmont