In the Sealed Grounds area of Faron Woods, there are birds called Chirri flying around. Targetting them and talking to Fi tells me "There is an 85% chance that its feathers can be used as some kind of material."
How do I get feathers from them?
I tried with the Bug Catching Net, but that's not working very well.
Best Answer
You get the feathers by catching the Chirri with the Bug Catching Net.
Now I know you said it, catching them is hard, but it's actually easy once you know the secret.
To be able to catch anything that could be caught, you need to sneak up on the target (i.e., walk up to it) and swing your net at it. It's easiest to swing sideways leading with the Wii Remote turned sideways. This applies to anything that is evasive or would otherwise run/fly away.
What I would do is sneak up to it with your net out and touching the target. Once you do that, swipe and it should be yours.
Here's a video demonstrating how you could do it: