Passerines -

It's called "Conditioning"..........and I do not mean the kind that goes in your hair:

When I saw this Purple Finch sleeping on a twig I attached to the feeder just an hour ago (September 22, 2013), I knew I was beginning to accomplish what I seek. I want to get the birds so conditioned to seeing me in the window that I can go right up to the window and not scare them. Although this bird is within 2-3 feet of me, it is sleeping!

That is trust. You can do this at your feeder too.