I only keep out nyjer seed. I don't want to feed the starlings & everyone here (goldfinches/purple house finches) seems to love it. Sparrows are meh on it. I also have some falcons that hang out in our area, so they keep the prairie dog populations down, which is good. But they don't seem to go after the squirrels, dunno why. The doves don't care too much for the nyjer seed, but every time I put out the "wild bird food" seed, I have it growing all over the place! Hate that... don't need millet growing all over my yard. Used to put out sunflower chips but the squirrels were destroying my feeders.
Supposedly, the reason why northern people aren't supposed to put out feeders during the winter is that it encourages earlier breeding for spring birds & for those who migrate not to migrate.. why should they when they have a ready food source? Earlier breeding means that the young probably won't survive the cold. But I've noticed that a lot of our birds that used to migrate aren't migrating anyways, and it's not because I'm feeding them (robins & starlings). I have been seeing this little grey bird that looks kinda like a chickadee, but doesn't have the cap. Really pretty little bird. Can't wait until summer when all the goldfinches are in full dress.. soooo pretty!!