The main ingredients inmost commercial birdseed mixes are sunflower seeds, peanuts, millet, maize flakes and hemp seeds. All of these are high in fat and other nutrients. Other popular ingredients are wheat, oats, freeze dried fruits, barley, vegetable oils, oyster- or other sea-shell grit, suet (lard), niger seed, aniseeed and dried worms (usually mealworms). In North America safflower seeds are also very commonly added.
You can make your own feeder table mix out of:
1 part each hemp, wheat and peanut granules (seed part of the peanut)
3 parts each of millet and pinhead oats (seed part of the oat)
2 parts each of kibbled maize and sunflowers (shelled)
The seed part of a peanut/oat is richer in protein than the entire peatnut/oat, thus their use in birdseed mixes.
An example ground-feeder mix recipe is:
1 part each sunflowers (ideally shelled), maize flakes, indigo wheat and kibbled maize
2 parts each of rolled oats and pressed insect pellets
3 parts millet.