True, the shells are biodegradable and decompose fairly quickly, but they stay around long enough to kill the grass in a big circle and also to be an attraction for squirrels:
To prevent this mess from occuring, it’s best to fill your feeders with something that doesn’t have shells. You can use cracked corn, for instance. You’ll still get debris below the feeder, but this will be eaten pretty quickly by the ground-feeding birds such as mourning doves and juncos.
Another suggestion is to purchase a special no-waste blend of bird seed. Duncraft makes a Super No-Waste Bird Seed. It contains sunflower hearts, cracked corn, peanut bits, and hull-free nyjer seed. It costs a little more than regular bird seed, but it’s worth it.
