Native Plants for Birds

The number that reframes the whole subject

A pair of chickadees raising one brood needs somewhere between six and nine thousand caterpillars to get the chicks to fledging. That figure comes from research by Doug Tallamy and colleagues at the University of Delaware, and it is the single most useful fact in bird gardening.

Almost no songbird raises its young on seed. Even species that eat seed as adults feed insects to nestlings, because growing birds need protein and fat that seed does not supply. Caterpillars are the preferred food: soft, boneless, and easy to carry.

That means a yard's value to breeding birds depends on how many caterpillars it produces, which depends almost entirely on its plants.

Native plants produce insects; introduced ones mostly do not

Insects specialize on the plants they evolved alongside. A native oak supports hundreds of caterpillar species. A ginkgo, a Norway maple, or a butterfly bush supports a small handful or none.

A yard planted with introduced ornamentals can look green and full and be, from a bird's point of view, close to empty. This is why bird gardening and native plant gardening turn out to be the same subject.

The heavy lifters are woody: oaks, willows, cherries, birches, and among the plants on this site, serviceberry, flowering dogwood, arrowwood viburnum, and spicebush. Native grasses and perennials contribute too.

Then feed the adults, across the year

Different foods matter at different times, and the fat content is what decides.

Fall migration needs high-fat fruit. Flowering dogwood, spicebush, Virginia creeper, arrowwood viburnum, and elderberry all produce it, and birds fueling for long flights seek it out specifically.

Winter needs the opposite: low-fat fruit that persists on the branch after everything else is gone. Winterberry, inkberry, bearberry, and fragrant sumac hold their fruit into January and February and act as a reserve.

Seed carries birds through fall and winter. Coneflower, blazing star, sunflower, cup plant, and the native grasses all supply it, and goldfinches in particular time their late nesting to seed availability.

Structure and the things not to do

Birds need cover as much as food: dense shrubs to escape into, thickets to nest in, and standing grasses for ground species. A yard of specimen plants in mulch has food and no shelter.

Three practices undo the rest. Leaving cats outdoors, which kill birds in the billions annually in the United States. Spraying insecticides, which removes the caterpillars the birds came for. And cutting the garden down in fall, which removes the seed, the shelter, and the overwintering insects in one pass.

Leave the stems standing until spring.

Sources: Doug Tallamy and University of Delaware research on native plants, caterpillar production, and chickadee nestling requirements; Cornell Lab of Ornithology (nestling diets, fruit fat content, and migration fueling); American Bird Conservancy and Smithsonian Migratory Bird Center (outdoor cat predation estimates).