From Badger Run Wildlife Rehab

Owls are shape shifters. They routinely make themselves look bigger or smaller depending on the situation. Sometimes they make themselves look long and thin in order to camouflage (look more like a branch when sitting in a tree). Other times, they puff up to look huge and scary when threatened.

The pictures below (*above now!) are of an African owl, the White-faced Scops owl. And no, this is not photoshop. They absolutely can skinny-up like this.

(Photo posted by Avian Conservation & Education Network back in 2018)