For owls that are superb.
US Wild Animal Rescue Database: Animal Help Now
International Wildlife Rescues: RescueShelter.com
Australia Rescue Help: WIRES
Germany-Austria-Switzerland-Italy Wild Bird Rescue: wildvogelhilfe.org
If you find an injured owl:
Note your exact location so the owl can be released back where it came from. Contact a licensed wildlife rehabilitation specialist to get correct advice and immediate assistance.
Minimize stress for the owl. If you can catch it, toss a towel or sweater over it and get it in a cardboard box or pet carrier. It should have room to be comfortable but not so much it can panic and injure itself. If you can’t catch it, keep people and animals away until help can come.
Do not give food or water! If you feed them the wrong thing or give them water improperly, you can accidentally kill them. It can also cause problems if they require anesthesia once help arrives, complicating procedures and costing valuable time.
If it is a baby owl, and it looks safe and uninjured, leave it be. Time on the ground is part of their growing up. They can fly to some extent and climb trees. If animals or people are nearby, put it up on a branch so it’s safe. If it’s injured, follow the above advice.
For more detailed help, see the OwlPages Rescue page.
From NYS Dept Of Environmental Conservation
This short-eared owl is showing off a behavior known as "rousing". Rousing is when a bird lifts and shakes out its feathers, often to rearrange displaced feathers and shake off water and dust during grooming. It's also a sign of a relaxed and content bird.
I think my chickens do that!
From some quick browsing, it seems like most, if not all birds will rouse. It sounds much like it serves most of the same functions as a puppy dog shake - floofing up the feathers/fur, shaking off water/dust, or for some invigoration after a nap.
I also stumbled on this short article about it as part of a pre-flight behavior and how as a photographer to use this understanding as a tool to catch take off shots:
All these things do line up with my own experiences watching birds.
Oh interesting!