Let's start out with the basics.  This is White Proso Millet, which, along with Red Milo (about twice the size of millet) is often used in less expensive bird seed mixtures as a cheap filler.  It has a low fat content, so it provides little energy for the birds.  Birds in the western U.S. enjoy these grains much more than eastern birds, with a few exceptions like juncos, chickadees and sparrows.  The small size and relative lack of appeal to most birds usually means that most of the Millet and Milo is pushed aside, and ends up on the ground below your wild bird feeders.  This is good news for the sparrows, doves and other ground feeding birds! 

Safflower is a relative newcomer to some wild bird seed mixtures.  It looks like a white sunflower seed, but studies have shown that many birds do not like it as much as sunflower seeds, except for cardinals, who may even grow to prefer it over all other seeds.  Other larger-billed wild birds, like grosbeaks and woodpeckers, will eat it as well... along with some smaller critters like chickadees, titmice and buntings.  It is a decent source of energy-laden fat, but again, not quite as much as sunflower seeds.  It does have a few distinct advantages over sunflower seeds... slightly lower cost, and it has a bitter taste that is unattractive to squirrels, as well as nuisance starlings! 

Striped sunflower seeds have tough hulls, and are only appreciated by the larger birds (and by human baseball players everywhere, who seem to enjoy spitting out a mouthful of the hulls just as the camera is on them!)  Cardinals, jays and woodpeckers are the most-likely takers, along with squirrels!  If you want to keep the squirrels happy, and maybe deter them from raiding your other feeders, place a ground level tray feeder with striped sunflower seeds well away from your other wild bird feeders.  Hulled sunflower seeds are a better choice for smaller target birds.

Now we're talking!  These are the most-liked goodies of all the commercially available bird feeds, black oil sunflower seeds.  Serve up these little tidbits, and you will please most of the wild song birds that might visit your feeders... cardinals, chickadees, finches, sparrows, grosbeaks, wrens, titmice, and woodpeckers alike.  You will like them because they dispense easily from all types of bird feeders, and they are widely appreciated by the birds because they have thin hulls that are easily cracked open, and the high fat content provides a welcomed energy boost.  If you select a seed mixture, look for a high percentage of these. 

Nyjer seed, sometimes spelled niger, or incorrectly called thistle seed (it does not come from the american thistle weed), is a favorite of our little finch buddies.  Nyjer can be expensive though since it is imported from India or Africa, and it is usually heat treated to "neuter" the seeds to keep them from germinating.  While the resulting Guizotia abyssinicia plants would not likely survive our climate, the import stipulations still require the heat treatment.  Nyjer seed was once just used for indoor pet birds, but is now commonly used for attracting wild birds like finches and siskins.  The very small size of nyjer usually requires a special bird feeder to dispense it, like a tube feeder with very small ports. 

Corn is often used to attract large wild birds, even game birds like turkey, ducks and quail... along with other wild animals like deer.  To be used in your wild song bird feeders, though, it is usually cracked like shown here.  In this more easily managed form, it can be ingested by bluebirds, dove and sparrows.  Generally, most wild song bird lovers do not present corn at their feeders because of the strong allure it has for squirrels, and the fact that most of the smaller birds that are more desirable either can't or won't eat it.  Like with striped sunflower seeds, you can use corn to keep the squirrels occupied away from your bird feeders. 

Peanuts can be an interesting food to present to your wild bird visitors in an array of forms.  Whole raw peanuts in the shell, as shown here, can be presented in a hopper feeder, or in a wire mesh basket with openings just large enough for jays and woodpeckers to yank them out.  Shelled peanuts can be presented in the same way, but the smaller size widens the array of possible takers to include buntings, chickadees, titmice and grosbeaks.  Peanut butter can be presented as well, sometimes spread in bark or pine cones, to attract wrens and flickers.  Of course, Mr. Squirrel will tear apart your feeder to get at peanuts... so keep that in mind!

Most of the above noted ingredients can be purchased in mixtures of varying percentages.  It is generally agreed upon that the bird seed mixtures available at larger chain grocery stores contain too high a percentage of the low-fat "filler" seeds mentioned above.  You may be able to find some worth buying if you look for large percentages of black oil sunflower seeds, or even nyjer.  Try your local bird supply store though for a more avian-friendly mixture.  Some of these blends include dried fruit, berries and nuts that will make your wild bird feeders much more appealing. 

Don't miss out on the varieties of wild birds that are attracted to fresh fruits, berries and jellies.  The obvious example here would be orioles and their love of oranges, but the possibilities go far beyond that.  Robins, woodpeckers, bluebirds, catbirds, tanagers and sapsuckers are just a few of the wild birds that will also eat oranges.  Mockingbirds and thrashers love apples.  If you have some over-ripe fruit, place it out there, and see who might stop by for a nibble!  Berries and jellies are also easy to present in tray feeders, give them a try.  Another "fresh" fare would be the tastey meal worms shown below.