Native trees and shrubs for birds: caterpillars, fruit, mast, nests and winter cover, month by month

Birds live on trees and shrubs in every month: caterpillars off the leaves in May, cherries in July, spicebush berries in September, acorns in November, holly fruit in February, a dead limb to nest in and an evergreen to sleep in. Native species do all of this and ornamentals from other continents mostly do not. In the suburbs of Washington, DC, Carolina chickadees held their numbers only in yards where native plants made up more than 70 percent of the plant biomass; yards below that line raised too few young to replace themselves. Across North America the breeding bird population has fallen by 2.9 billion since 1970, more than one bird in four. What grows on your ground is the part of that you control.

Caterpillars first: what nestlings are made of

Almost every songbird in a yard, whatever it eats in winter, raises its young on insects, and most of those insects are caterpillars. Ninety-six percent of North America’s land birds depend on insects, and at least 310 species prey heavily on caterpillars. It may take 6,000 to 9,000 caterpillars in a season for a pair of Carolina chickadees to raise one brood of five. Catbirds and nuthatches feed their nestlings almost nothing else.

Caterpillars come from native woody plants because most moths and butterflies can eat only the plants they evolved with, which the Lepidoptera article covers in full. In the eastern forests, oaks host 436 species of caterpillar, the cherries and plums 340, birches 284, hickories 213, alders 173, basswood 132, walnuts 125, chestnuts 115, hazels 108, dogwoods 98 and serviceberries 92. Counting caterpillars in the Washington yards, Desirée Narango’s team found 20 or more in five minutes on a native oak and one or none on nonnative plants. The chickadees in yards full of ornamentals switched to spiders and fledged fewer young. The counts were made from mid-May into early June, when the nestlings are being fed. The beetles, sawflies and flies that follow are the insects article’s subject.

Fruit, season by season

Once the young have fledged, fruit takes over. Each native species ripens when a particular set of birds needs it, and the fat content matches the job.

Summer, June to August. Downy serviceberry (Amelanchier arborea) and Allegheny serviceberry (Amelanchier laevis) ripen in June and July; at least 40 bird species eat them, including cedar waxwings, cardinals and orioles. Red mulberry (Morus rubra) fruits from June to August for bluebirds, catbirds, kingbirds, orioles, tanagers and woodpeckers. Black huckleberry (Gaylussacia baccata) ripens in the second half of July, red elderberry (Sambucus racemosa) through the summer for at least 50 songbird species, black elderberry (Sambucus canadensis) in August and September; black cherry, which we do not sell, ripens in late summer.

Fall migration, late August to October. A warbler or thrush leaving for the tropics has to build fat before it goes, and the fruits that ripen now are the fattest of the year. Spicebush (Lindera benzoin) fruit is nearly half fat, ripens from August into October and is a particular favorite of wood thrushes and veeries; only female plants bear it, so plant several. Flowering dogwood (Cornus florida) fruit is high in fat and calcium, ripens in September and October and is stripped by robins first, then thrushes, bluebirds, cardinals, towhees, thrashers, woodpeckers and wild turkeys. Black gum (Nyssa sylvatica) ripens at the same time and is one of the most important fruits of the migration for thrushes, robins, flickers, mockingbirds and thrashers. Silky dogwood (Cornus amomum) fruit runs about 10 percent fat by dry weight; gray dogwood (Cornus racemosa) runs 28 to 37 percent, and arrowwood viburnum (Viburnum dentatum) 42 to 50 percent in a New York study. American beautyberry (Callicarpa americana), nannyberry (Viburnum lentago), blackhaw (Viburnum prunifolium) and Carolina buckthorn (Frangula caroliniana) carry fall fruit for songbirds.

Winter, November to March. The fruits that hang on into winter are the ones birds pass over in fall, usually because they are low in fat. Hackberry (Celtis occidentalis) fruit is under 5 percent fat and stays on the tree from late August into March, which is why it can feed waxwings, robins, bluebirds, mockingbirds and flickers in February. American holly (Ilex opaca) ripens from September to December and holds its fruit through most of the winter for at least 18 bird species. Winterberry (Ilex verticillata) does the same for robins, waxwings, catbirds and bluebirds, and needs one male within 50 feet for every ten females. Staghorn sumac (Rhus typhina) ripens by September and lasts all winter; in a New York study birds ranked its fruit last of five, which is why it is still there in March for pheasants, quail and turkeys. American mountain ash (Sorbus americana) keeps its berries all winter for robins, waxwings and grouse, and Washington hawthorn (Crataegus phaenopyrum) and American crabapple (Malus coronaria) hold fruit into spring for waxwings and turkeys. Eastern red cedar cones are eaten mainly in winter by waxwings, bobwhites, grouse and turkeys, and northern bayberry (Morella pensylvanica), whose waxy fruit lets yellow-rumped warblers winter farther north than most warblers, holds fruit above the snow all winter.

Mast: acorns and nuts

White oak acorns feed blue jays, bobwhites, mallards, grouse and wild turkeys; red-headed and red-bellied woodpeckers gather acorns and beechnuts in fall and jam them into bark crevices for later. White-group acorns go in the fall and red-group acorns last into winter, so an oak of each group keeps the table set, as the oak article explains. Blue jays are the oaks’ planters. In Blacksburg, Virginia, jays carried off and buried 133,000 acorns from one stand of pin oaks, 54 percent of the crop, an average of 0.7 miles and as far as 1.2 miles; they chose the small and medium acorns of pin, willow and black oak and beechnuts, and left the big acorns of red and white oak. Every oak we sell feeds birds: bear oak (Quercus ilicifolia) acorns go to game birds and songbirds, overcup oak (Quercus lyrata) acorns feed ducks and turkeys, and dwarf chinquapin oak (Quercus prinoides) bears within a few years of planting.

Shagbark hickory (Carya ovata) nuts feed wood ducks, turkeys, blue jays, nuthatches and red-bellied woodpeckers. Allegheny chinquapin (Castanea pumila) nuts are taken by blue jays, pileated and red-headed woodpeckers and turkeys, and American hazelnut (Corylus americana) feeds bobwhites, ruffed grouse, turkeys and songbirds. Black walnut (Juglans nigra) and pecan (Carya illinoinensis) go mainly to squirrels.

Sap, buds, catkins and seeds

The parts nobody thinks of feed birds too. Yellow-bellied sapsuckers drill wells in birches, maples, hollies and hemlocks, and hummingbirds, waxwings and red-bellied woodpeckers drink at them; the sapsucker article covers who comes to the holes. Ruffed grouse live on buds through the winter, and the buds and catkins of hop hornbeam (Ostrya virginiana) are an important winter food for them; the nutlets go to turkeys, purple finches, rose-breasted grosbeaks and downy woodpeckers. American hornbeam (Carpinus caroliniana) seed is eaten by yellow-rumped warblers, grouse and bobwhites. Redpolls, pine siskins and goldfinches feed on the catkins and seeds of alders and birches; smooth alder (Alnus serrulata) flowers in March and carries seed in small cones after. Eastern redbud (Cercis canadensis) pods hang through winter, and goldfinches and quail work the seed out of them. Bald cypress (Taxodium distichum) seed goes to wood ducks and turkeys, and black locust (Robinia pseudoacacia) seed to bobwhites and grouse.

Nectar for hummingbirds

The ruby-throated hummingbird reaches the Mid-Atlantic in mid-April, before most flowers, and drinks at sapsucker wells until the trees bloom. Red buckeye opens in early spring and is a tree that feeds it on the way north; we do not grow it. Pinxterbloom azalea (Rhododendron periclymenoides), the pink native azalea of the Mid-Atlantic woods, opens in April and May and does. Among ours, black locust flowers from April to June and is a favorite of hummingbirds and honey bees, Carolina silverbell (Halesia tetraptera) draws hummingbirds, and other birds eat its buds, and rosebay rhododendron (Rhododendron maximum), mountain laurel (Kalmia latifolia), sweet pepperbush (Clethra alnifolia), eastern redbud, red elderberry and Washington hawthorn all draw hummingbirds to their flowers. The bees that share these flowers are the bee article’s subject. A hummingbird nests 10 to 20 feet up on a thin limb, in a cup of plant down and spider silk shingled with lichen, and a female catches up to 2,000 insects and spiders to raise her young, so the same trees feed and house her.

Nests, cavities and dead wood

In Pennsylvania 35 species of birds and 20 mammals nest or den in tree cavities. Seven woodpeckers dig the holes that decay does not open: pileated, northern flicker, yellow-bellied sapsucker, hairy, downy, red-headed and red-bellied. A pileated woodpecker digs a new nest every year in a dead tree or a dead limb of a live one, 15 to 80 feet up, and lives largely on carpenter ants; the old holes go to wood ducks, screech owls, great crested flycatchers, tree swallows, chickadees, nuthatches, wrens and bluebirds. American basswood (Tilia americana) decays easily and produces a disproportionate number of cavities, used by wood ducks and pileated woodpeckers. Black gum hollows out and holds nests, bats and tree frogs, and American holly cavities house red-cockaded woodpeckers in the South. Leave snags that stand clear of targets, leave the tops that fall, and treat a hollow tree as habitat; a field edge can carry five to ten den trees an acre.

A wood thrush builds 10 to 15 feet up in the fork of a deciduous tree, a cedar waxwing 6 to 20 feet up on a horizontal limb, a yellow-rumped warbler out on a conifer branch, a ruffed grouse on the ground under dense brush. Thickets of American plum (Prunus americana) are the main breeding habitat of seven songbirds in the shrub stage of Piedmont old fields, black elderberry is an excellent nest site, Washington hawthorn and American crabapple branches hold nests, and eastern red cedar is a favorite nest tree of chipping sparrows, robins and mockingbirds.

Cover and winter shelter

A bird in January needs a windbreak more than a feeder. Evergreens belong on the side the winter wind comes from. Eastern red cedar is roosting cover for screech owls, saw-whet owls, juncos and yellow-rumped warblers. Hemlock gives winter cover to grouse and turkeys and nests to black-throated green and blackburnian warblers. American holly is winter cover as well as winter fruit, rosebay rhododendron thickets are winter and escape cover for grouse, turkeys and songbirds, and mountain laurel shelters screech owls and grouse. Deciduous cover counts too: young oaks that hold their dead leaves are often the only brushy winter cover in a young stand, so marcescence is worth something to a bird, and thickets of American hazelnut, American plum and black huckleberry hide birds and nests. Under all of it, leaf litter is where birds find insects all winter, which is the habitat article’s argument.

Why native, with the numbers

Three lines of evidence say native species, not just any tree. First, the caterpillars. A 2009 ranking of all 1,385 plant genera growing in the Mid-Atlantic found that native woody plants supported far more species of moths and butterflies than introduced ones. On six pairs of properties in southeastern Pennsylvania, the yards landscaped with natives had more caterpillars, more birds and more breeding pairs, and birds of regional conservation concern were 8 times as abundant.

Second, the fruit. In Rochester, New York, native shrub fruits ran from 6.6 to 48.7 percent fat by dry weight and invasive fruits no more than 1 percent, with common buckthorn at 0.3 percent. Migrating warblers and sparrows caught where 83 percent of the fruit crop was native dogwood and arrowwood carried more of the blood fats that show weight gain than birds at a site where wild grape made up most of the crop. The invasive shrubs also spread on the birds that eat them and choke a woods.

Third, the cultivars. When native shrubs bred for red, blue or purple leaves were tested against the wild type, insects fed on them less in every trial. Buy the straight species, and for spicebush, winterberry and holly buy both sexes; a flowering cherry or plum sold for its blossoms usually sets no fruit at all.

The best trees and shrubs for birds, ranked

1. An oak. More caterpillars than anything else, acorns for jays, woodpeckers and turkeys, a trunk that eventually hollows. White oak and northern red oak are the everyday choices and we do not sell them; we grow swamp chestnut oak, cherrybark oak, overcup oak and the shrub oaks.
2. Black cherry. 340 caterpillar species on the genus and late-summer fruit for robins, thrashers, bluebirds, catbirds, waxwings, thrushes and vireos. We do not sell it; American plum and beach plum (Prunus maritima) share the genus.
3. Flowering dogwood, with silky dogwood in wet ground and gray dogwood for the fattest fruit of the three.
4. Spicebush, for the thrushes.
5. Black gum, for the migration and, in old age, the hollows.
6. The serviceberries, for June.
7. Eastern red cedar and American holly, one evergreen for fruit, roosts and nests. Red cedar is the better bird tree and we do not sell it.
8. Winterberry and staghorn sumac, for February.
9. Black elderberry and red mulberry, for summer fruit and nest sites.
10. Shagbark hickory, American hazelnut and Allegheny chinquapin, for mast.
11. Hop hornbeam, American hornbeam and smooth alder, for winter buds, catkins and seed.
12. Black locust, the hummingbird tree we grow.

Hackberry for the winter fruit, sassafras (Sassafras albidum) for its high-fat fall fruit, arrowwood viburnum and northern bayberry belong on this list as well; all four joined the catalog with this article.

How to plant for birds

• Plant in layers. A thrush, a waxwing, a warbler and a grouse nest at four heights, so put a canopy tree, a small tree, shrubs and unmown ground together, not one specimen in a lawn.
• Plant for the calendar. Serviceberry for June, elderberry for August, spicebush, dogwood and black gum for the migration, holly, winterberry and sumac for the winter, an oak for the mast and an evergreen.
• Plant in groups. A single spicebush or winterberry is a male or a female; three or more fruit. Thickets, not specimens, hold nests.
• Leave dead wood and litter. Snags, fallen tops and a stick pile; rake nothing under the drip line.
• Water. A shallow basin an inch or two deep, kept clean, in the open.
• Skip the insecticides. White-crowned sparrows that ate the equivalent of a few neonicotinoid-treated seeds lost 6 percent of their body mass in six hours and delayed their migration by three and a half days.
• Cats and glass. Outdoor cats kill about 2.4 billion birds a year in the United States and building glass about 600 million. Keep cats in, and mark any window that reflects the yard with dots or lines no more than 2 inches apart.
• Pull the invasives and do not plant the ornamentals that started them: bush honeysuckle, autumn olive, privet, burning bush, barberry and Callery pear.

Where to start

Plant one oak this fall, and under it a spicebush, a flowering dogwood and a serviceberry. Add a holly or a red cedar where the winter wind comes from, and an elderberry or American plum thicket along the edge. Stop cutting dead limbs that threaten nothing, stop raking under the trees and stop spraying. Keep the cat in. Then count birds in May, and let the tree finder match the rest of the list to your ground.

Sources

• Nonnative plants reduce population growth of an insectivorous bird: Narango, Tallamy and Marra, Proceedings of the National Academy of Sciences 115 (2018), open-access copy at PubMed Central: Carolina chickadees in 159 Washington, DC yards, the 70 percent native biomass threshold, the switch to spiders, the mid-May to early June caterpillar counts and the 310 bird species that prey on caterpillars.
• Keystone Native Plants: Eastern Temperate Forests, Ecoregion 8: National Wildlife Federation, from Douglas Tallamy’s data: the caterpillar species counts by genus (oaks 436, Prunus 340, birches 284 and the rest) and the 96 percent of land birds that depend on insects.
• New Research Further Proves Native Plants Offer More Bugs for Birds: National Audubon Society (2017): the 6,000 to 9,000 caterpillars a chickadee pair needs for a brood of five, and Narango’s 20 caterpillars in five minutes on a native oak against one or none on nonnative plants.
• 3 Billion Birds Gone: Cornell Lab of Ornithology and partners, summarizing Rosenberg and others, Science (2019): 2.9 billion breeding birds lost since 1970, more than one in four.
• The Value of Native and Invasive Fruit-Bearing Shrubs for Migrating Songbirds: Smith, DeSando and Pagano, Northeastern Naturalist 20 (2013): native shrub fruits at Rochester, New York ran 6.57 to 48.72 percent fat by dry weight and invasive fruits no more than 0.99 percent.
• Local site variation in stopover physiology of migrating songbirds near the south shore of Lake Ontario is linked to fruit availability and quality: Smith, Miller, Merchant and Sankoh, Conservation Physiology 3 (2015), open-access copy: fat content of gray dogwood (28 to 37 percent), silky dogwood (10 percent), arrowwood (42 to 50 percent) and common buckthorn (0.3 percent), and the higher plasma triglycerides of warblers and sparrows at the site where 83 percent of the fruit was native.
• Acorn dispersal by the blue jay (Cyanocitta cristata): Darley-Hill and Johnson, Oecologia 50 (1981): 133,000 acorns, 54 percent of a pin oak crop in Blacksburg, Virginia, cached a mean of 1.1 kilometers away, with a preference for small and medium acorns over those of red and white oak.
• Do Cultivars of Native Plants Support Insect Herbivores?: Baisden, Tallamy, Narango and Boyle, HortTechnology 28 (2018): cultivars with leaves changed to red, blue or purple deterred insect feeding in all three experiments; habit, disease resistance and fruit size showed no consistent effect.
• Dead Wood for Wildlife: Penn State Extension: 35 bird and 20 mammal species use cavities in Pennsylvania, the seven woodpeckers that excavate them, the secondary users, and five to ten den trees an acre at field edges.
• Attracting Ruby-throated Hummingbirds to Your Yard: Rutgers New Jersey Agricultural Experiment Station (2020): arrival in mid-April, redbud, red elderberry, pink azalea and tuliptree as hummingbird plants, the lichen-covered nest, and the 2,000 insects a female catches for her young.
• Threats to Birds: US Fish and Wildlife Service: median annual bird deaths by cause, 2.4 billion to cats and 599 million to building glass, from Loss and others (2013, 2014).
• A Widespread Pesticide Causes Weight Loss and Delayed Migration in Songbirds: National Audubon Society (2019), reporting Eng, Stutchbury and Morrissey in Science: white-crowned sparrows dosed with imidacloprid lost 6 percent of body mass in six hours and delayed migration 3.5 days.
• Cornus florida, Fire Effects Information System: USDA Forest Service: flowering dogwood fruit is high in fat and calcium, ripens in September and October, matters most to robins and is eaten by thrushes, bluebirds, cardinals, towhees, thrashers, woodpeckers and wild turkeys.
• Native Plants of PA: Spicebush (Lindera benzoin): Penn State Extension: spicebush fruit is nearly 50 percent fat, ripens in fall for wood thrush, veery, bobwhite and catbird, and only female plants bear it.
• Ranking lepidopteran use of native versus introduced plants: Tallamy and Shropshire, Conservation Biology 23 (2009), abstract on PubMed: the 1,385 Mid-Atlantic plant genera ranked, with native woody plants supporting far more moth and butterfly species than introduced ones.
• Impact of native plants on bird and butterfly biodiversity in suburban landscapes: Burghardt, Tallamy and Shriver, Conservation Biology 23 (2009), abstract on PubMed: six pairs of southeastern Pennsylvania properties, with more caterpillars, more birds and more breeding pairs on the native-landscaped ones and birds of regional conservation concern eight times as abundant.