You don't trust your wings because you don't trust the air.

From Alfred’s journal

A young jay spent the whole afternoon on the low rail of the Mercers' fence, opening his wings and folding them again, opening and folding, like a man checking a watch that has stopped. I assumed for years that a bird in that state is doubting his own feathers, because that is what I did at his age, counting my primaries as though one of them had gone missing in the night. But I watched him longer than was polite and he was not looking at his wings at all. He was looking at the gap. You don't trust your wings because you don't trust the air, and the air that day was doing nothing to earn it, flat and warm and empty over the yard with not a leaf turning. He went at dusk, when a little wind came up off the field and gave him something to push against.