To prevent the spread of some avian diseases, food should not be spread on the ground, and feeders should be cleaned and disinfected regularly. Other Attractions for Birds.Birds do not have teeth; instead, they grind food in their gizzards. Birds eat small pieces of sand and gravel, or "grit" to aid the grinding process. In winter, when the ground is covered by snow, suitable grit may be hard to find. You can supply grit to birds at the feeder in the form of crushed eggshells, coarse sand, or from boxes of grit that are sold at variety and pet stores.
Snags provide "hawking" perches for flycatchers and resting perches for swallows. Flycatchers perch on a branch, fly out to snatch insects, and then return to the same branch to watch for other insects. Large natural cavities, formed in snags by decay, often provide homes for a variey of mammals including marten, porcupine, bats, bushy_tailed woodrats, northern flying squirrels, and other species. When left to decay and fall over naturally, large hollow snags may provide den sites for larger animals like mink, lynx, red fox, and wolverine. To help provide homes for this wide variety of animals, leave dead trees standing whenever possible, particularly snags larger than 6 inches in diameter and/or any containing woodpecker holes or other cavities.