We've been feeding the birds in our backyard for about 6yrs and here's what I've noticed. We now how have more of the birds we started feeding.
For a couple years we only had one male Hairy Woodpecker, and then one year he showed with a mate! We were thrilled, even more so when they brought the young-ins to feed as well.
We didn't have any Chickadees for about the first four years, and then one year a pair built a nest in one of our birdhouses, and now we have Chickadees all the time in the winter. We like to think it's the family that was born here, but who knows.
We've had Baltimore Orioles stop in, in the spring and fall on their way through, but last year they were here all summer with the family!
We now also now have 2 or 3 pairs of Cardinals and Downy Woodpeckers around on a regular basis, when in the first couple years it was just one.
We have more Gold Finches, House Finches and Junkos this year then ever before and the Blue Jays seem to be around more.
We put feed out all year, and have a wide variety of seed, feeders, water, native plants, and shelter. They have it pretty good here.