Many birds that by nature forage for seed on the ground, such as mourning doves and dark-eyed juncos and other sparrows, will not visit a hanging feeder. (There are always exceptions, even within species, of course.) Here's how to support these kinds of birds with supplemental seed.
Ground-feeding birds will often eat the seed that falls from hanging feeders. You can also intentionally spill seed on the ground for them when filling the feeder.
Favorite seeds among ground feeders are white proso millet and sunflower seeds. Larger species also enjoy oats.
To help keep ground feeders healthy, periodically rake the ground beneath feeders to remove seed hulls, bird waste and spoiled seed. Ground-feeding birds are an easy target for cats, so keep your felines indoors.
Consider sprinkling grit in a location away from feeders for birds that consume it to aid their digestion. Grit can be bought at birding and farm-supply stores, or you can make your own using untreated coarse sand or fine gravel and egg or oyster shells. Sanitize the shells by boiling them for 10 minutes, and then crush them well.
There are short-legged platform feeders designed for ground-foraging birds. Look for one with a screen as its platform, so that it drains water away from the seed. Some are roofed for further protection from the elements.