This winter I had the good fortune of seeing a Northern Pygmy Owl and shortly after a Great Grey Owl. The Great Grey was a new bird for me in the Fraser Valley and one I have not seen for quite a few years. Impressive birds to say the least. Both species are fairly tolerant of people and I enjoyed watching them hunt.
The Great Grey once changed perches by flying no more than four feet over my head before landing just behind me. I have to admit I did flinch as it approached from the higher perch to the lower one behind me. That's a big owl with decent wing span and those yellow eyes are striking as they got closer and closer...and closer. All was done without a sound which added to the experience.
These guys stand about 7 inches high but can take birds as large as an American Robin or Flicker who are in the realm of 10 and 12 inches in length respectively. This guy was hunting mice when I saw him. Pygmy Owls are dedicated daytime hunters.
Great Grey is about 27 inches and if heavier would be both the largest and heaviest North American Owl. Great Horned is a heavier owl even though they look smaller next to a Great Grey. They will hunt during the day but prefer the night. A Great Grey active in the day is probably hungry and worth leaving plenty of room to do their thing.