How to catch the fairy in the sealed grounds

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:

If you're asking about the plain old Mushroom Spores, the spores you get from any plain mushroom, then I'm convinced that they serve no other purpose in the game and only have a one time use.

Healing Orielle's Loftwing

I've done a fair amount of testing and could not find a single use for them. Everything I've tried it on does absolutely nothing:

• Hearts (On flowers or on their own)
• Rupees (Green, Blue, and Red)
• Ammo (Seeds, Bombs)
• Catchables (Grasshoppers, Hornets, Rhino Beetles, Non-Blue Birds)
• Enemies (ChuChus, Bokoblins, Octorocks, Guays, Babas, Keese)
• Friendly Characters (Kikwis, The old lady in the temple, townspeople)
• Diggable holes
• Breakables (Pots, Bushes, big fruits)
• Other mushrooms (non-sparkling and sparkling)
• Bird Statues
• Other interactive items (Sticky Plant Bombs, Stamina Fruit, Chairs, Ropes, Trees, etc.)

If on the other hand you are asking about the Glittering Spores, the spores you get from the glittering mushrooms, they have very limited uses AFAIK. There's only a couple of uses that I know of.

You can use it on Hearts or Rupees to change them. Hearts turn into Fairies. Rupees turn into different valued rupees, even a Rupoor.

On some of the smaller enemies, it knocks them dizzy. I was only able to do this on Bokoblins, Octorocks and Babas (the plants) but didn't have enough to test on others.