This Barred Owl broke out into a real frown when a Great Blue Heron landed in the top of a cedar tree overhead and was perched there for several minutes. The owl was as still as a post the entire time and only when the heron flew off did the owl go back to it’s normal relaxed soft eyed posture. This change of expression was amazing to watch and so obvious... the owl definitely saw the heron as a threat and a predator.

OK, so who knows how many muscles it takes for an owl to have a sour face?