There are 5 Owls to track down and return to the Owl Forest in Mahag Saar for Tales of Arise. These are completely optional but offer multiple Trophies/Achievements while granting you rewards mostly in the form of cosmetics.
Owl #22 - Niez
In Niez, head east from the exit to Mount Dhiara and you’ll come across a a fountain with a statue. Look in the corner here to spot a bucket where the Owl is sitting, this one rewards you with the Red Rose Corsage.
Owl #23 - Aqfotle Hills
When entering Aqfotle Hills via Niez, keep to the left while heading west and you’ll come across some ruined houses. The Owl sits on the first and will hand over the Retro Sunglasses.
Owl #24 - Adan Lake
Head to the lake in the center of the area and you’ll find a gate that will lead to the northern part of the map. Head west as far as you can at the intersection and then you’ll notice the path loops back around to the east, albeit at a higher elevation. Drop down to the area below and after taking out the enemies here, look on top of the wall to the north to spot the Owl, this will present you with the Angry Glasses.
Owl #25 - Adan Ruins
Enter Adan Ruins via Aqfotle Hills and keep to your right, you’ll find a small platform you can drop off to reach another. Ignore this, but stand on the edge and turn the camera to the west to spot the Owl on the wall here, this one will hand over the Angel Wings.
Owl #26 - Mobile Fortress Gradia Ship Interior Level 2 / Thistlym
Mobile Fortress Gradia is a one-time visit however this is not missable, it will just appear in Thistlym if you miss it during your first time. Once you reach Ship Interior Level 2, head to the second cabin from the left in the northeast and you’ll find the Owl on a table near the door. If you miss it here, head to Thistlym in Ganath Haros and make your way to the water, the Owl will be near the fisherman on the pier. This Owl will hand over the Butterfly Wings.