As you say owls are good at camouflage. It would be very strange if you would have been able to see them during the day as they would not have been doing a good job of hiding. Owls generally look like tree trunks and will find suitable tall trees far from people to hide in. They can also hide in hollowed out trunks where they make their nests. You do need a good eye to be able to spot a camouflaged owl high up in a tree hidden by all the branches but finding one in its nest is almost impossible.
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