Owls (and a few other birds like ospreay) are sometimes referred to as semi-zygodactyl. Zygodactyl feet are usually in a fixed 2 x 2 configuration, woodpeckers being a common example, while the owl can hold its hallux (their equivalent of our big toe) toward the front or back.

There is a pretty neat study with some graphs done on osprey to show what foot configurations they use for different activities (3x1/2.5x1.5/2x2).

Owl toes ftw