After finding Ruu and then following him to find his brother and sister, you'll have a brief conversation about removing foreign objects from the location, and in this case, means weird-looking feathers.
Upon touching the perch, three glowing objects will fly in different directions, and you have to use Elemental Sight to locate them. When you find a feather, just interact with it, and a message will appear, telling you how many of the three you have collected.
Where to find the three feathers
Feather one is located close to the perch. If you look east from the perch when using Elemental Sight, you'll see the feather.
The second feather is further down south. Follow the strange light pillars, and just keep Elemental Sight on, and as you turn the corner at the bottom, you'll see the feather.
The third feather is to the left of where you found the second one. You'll see a rock that you can climb up. Climb up and at the very top is the third feather, overlooking the perch and Ruu if you could see through the fog.
Once all three are collected, go back to the perch, and continue on with the quest.
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