Free food for bird brains

A month ago I installed a finch feeder

and a hummingbird feeder. I have two cats, but I've seen hummingbirds feed from flowers on the front lawn where they could (theoretically) be caught by the cats. I think I've heard finches. Both feeders are high above the ground far from where the cats could climb. Yet I've never seen any bird feed from them. The hummingbird liquid is going down slightly, so it could be getting fed from or evaporating. The finch feeder is down a touch. My friend Chris told me it takes me a month for the finches to notice and feed. Why does it take the birds so long to notice and get free food? I hear birds are smart, but this sounds very dumb to me. Oh, well. At least now they're using it. I just wish I could see them feed.