There are 9 Owls to track down and return to the Owl Forest in Calaglia for Tales of Arise. These are completely optional but offer multiple Trophies/Achievements while granting you rewards mostly in the form of cosmetics.
Owl #1 - Sandinus Ravine
As you pass through the Sandinus Ravine, you’ll eventually cross a bridge just before the entrance of Ulzebek comes into view (and after you see the Gigant). Once crossed, look on the tree to the right to spot the first Owl that will present you with a Dog Tail.
Owl #2 - Ulzebek
When you reach Ulzebek for the first time, there will be a cutscene at a house to the northeast where Zephyr is. Once the cutscene has concluded, climb the ladders to reach the roof and then look to the right to find this Owl perched on a clothesline, this will present you with some Rabbit Ears.
Owl #3 - Iglia Wastes
Iglia Wastes is the largest map in Calaglia and if you head to the southwest, you’ll find some vines you can climb to reach a higher area. Once there, head to the south as far as you can and you’ll find a tree with this Owl perched on. Discovering this Owl will present you with the Spotted Cat Ears.
Owl #4 - Kyrd Garrison
Kyrd Garrison is another large map with many places to search for the next Owl. Thankfully, this is an easy one to locate, simply make your way towards the entrance of Mosgul and head up the path to the north. Once it opens up, head south and turn the camera to the left to find this Owl. Discovering this Owl will present you with the Cat Tail.
Owl #5 - Mosgul
You won’t be able to discover this Owl until you make your way back to Mosgul during the Renan attack. You’ll enter from the Kyrd Garrison side and after you’ve won the two mandatory battles against the Calaglia Swordsmen, walk out onto the platform to the south, sat on a cart. Turn the camera to the left and you’ll spot this Owl perched on some rocks. Discovering this Owl will present you with the Monocle.