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Songbird Hedges—An Antidote to the Stockade Fence
Plants & Gardens News Volume 16, Number 3 | Fall 2001
by Janet Marinelli
It's time to bid goodbye to the stockade fence. For the past couple of decades, warrens of these wooden barricades with their monotonous rows of tall, tight-fitting slats have been metastasizing across the continent. Even worse are the shiny plastic monstrosities that are the latest thing in residential fencing.
A songbird hedge, butterfly meadow, and manicured lawn co-exist peacefully in a Long Island yard. [Photo credit: Victor Schrager]
Walling the garden off from animals, invaders, nosy neighbors, or even hot, dry desert winds is a venerable tradition dating back thousands of years. Fortunately, our modern gardens are rarely threatened by marauding barbarians or ravenous wolves. We may want to mute the sounds of street traffic, screen unsightly panoramas, or attain a modicum of privacy, but do we have to allude to cattle pens or cavalry forts of the Wild West era to accomplish these goals?
Here's my modest proposal for an alternative to the stockade fence: a songbird hedge. Hedges give our gardens not only the structure of architecture but also the complexity of the natural world. Unlike wooden or (shudder!) plastic fencing, a hedge is alive, a meaty project for any red-blooded gardener. Hedges can define property boundaries without being a slap in the face to the folks who live next-door. With a bit of attention to plant selection, they can provide much-needed habitat for feathered friends as well—especially the migrating songbirds that have been declining in recent years. I'm not talking about formal (and back-breaking) hedges that need to be clipped as meticulously as a poodle, but rather spectacular mixtures of flowering and evergreen trees and shrubs left to follow their own growth habits. Such plantings can transform our backyards into bed-and-breakfasts for migrants and ease the plight of warblers, vireos, thrushes, and other threatened songbirds.
Emaciated Migrants
I've been known to complain about the two-and-a-half-hour drive from my Manhattan apartment to my family's summer cottage on Shelter Island. But at least I know where I can stop for some comfort food when I've had my fill of the road rage on the Long Island Expressway. That's not the case for migrating songbirds. The rigors of spring and autumn migration leave them in unfamiliar landscapes when they're close to their physiological limits. They don't have the luxury of seeking a better meal or place to rest.
Every spring millions of migrants fly 600 miles or more from the Yucatan Peninsula clear across the Gulf of Mexico. The avian voyagers proceed in waves up through the East, Midwest, and Plains states. Many continue to the vast coniferous forests of Canada, or as far north as the Arctic. Species that breed in the western states, including the endangered southwestern willow flycatcher, may have to fly for hours over inhospitable terrain in the Chihuahuan Desert before they can find refuge in the relatively lush vegetation of bosques along the middle Rio Grande. And since the 1950s these biannual migratory marathons have become even more of a challenge: Vast stretches of natural habitat along North America's major coastal and inland migration routes have been carved up and developed, contributing to the decline of some songbird species.
To ensure that they reach their breeding or wintering grounds alive, migrants must put on enormous amounts of fat. A blackpoll warbler, for example, which breeds in Canada, can almost double its weight, ballooning from about 12 grams (half an ounce) to more than 20 grams. The extra fat makes it possible for the tiny bird to fly nonstop between the New England coast and the north coast of South America. But most songbirds can't accumulate enough fat to make their trips in one continuous flight; they need to stop several times to rest and refuel. They depend on finding suitable "stopover" habitats, places with an abundant supply of emerging insects in spring and fruits and bugs in fall. If high-quality habitat is not available, even exhausted and emaciated migratory birds must continue until they find adequate food and cover. If they're too thin or weak to continue, they'll either starve or succumb to predators. It's estimated that half of all migrants heading south for the winter won't return to breed in spring. Fortunately, according to scientists, even small patches of stopover habitat can mean the difference between successful migration and starvation for many species.
Studies have demonstrated that shelterbelts—long, relatively narrow plantings of trees and shrubs first promoted in the mid-1930s to reduce soil erosion—are important stopover habitats in the Plains states. In fact as recently as 60 years ago, fields and pastures bordered by hedgerows dominated the landscape in the eastern two-thirds of the country. Mature hedgerows typically included some tall canopy trees, along with beautiful understory trees and shrubs such as native viburnums. Songbirds flourished in this environment. With a little help from us gardeners, they can again.
Songbird Magnets
The key to creating an effective songbird hedge or hedgerow is to incorporate as many of the different layers of plants found in a healthy forest as possible: the tallest trees that form its roof or ceiling, smaller understory trees, shrubs, and groundcovers. Vines often connect the various vertical layers, clambering up bushes and high into the trees. Landscapes with all these layers, especially shrubs loaded with berries, are magnets for migrating songbirds.
The goal is to re-create the gamut of habitat niches preferred by different species. Evidence suggests that migrant songbirds aren't fussy about vegetation type, the particular species that comprise a plant community—an oak and hickory forest, say, or a spruce and fir forest. Blackburnian warblers, for example, breed in the coniferous forests of Canada but feed in deciduous forests while migrating through most of the United States. However, migrant songbirds are more particular about vegetation structure and vertical layers: The prothonotary warbler has a definite affinity for shrubby thickets, whereas the magnolia warbler favors both tall and understory trees. Two-thirds of all the migrants observed in one study were found in shrubs and understory trees—the layers most often missing in the typical residential landscape.
To create a hedge or hedgerow in the East, South, Midwest, or Plains states, plant the center or tallest part first with a few scattered oak or other canopy trees; consider buying the more natural clump forms rather than the standard single-trunk, shade-tree forms. On either side and among the taller species, plant flowering understory trees (dogwoods are among the best) and a few evergreens. After all the trees are installed, add a diverse mixture of fruiting shrubs and a vine or two, and finally, some nectar plants for migrating hummingbirds. If your property is small, leave out the largest trees and choose the more compact varieties of understory trees and shrubs.
If there already are tall trees along the periphery of your property, plant understory trees and fill in the gaps with shrubs, the more different types the better. Many migrants are attracted to thickets, dense masses of fruiting shrubs, vines, briers, and brambles. Native trees and shrubs are best, because they are genetically programmed to leaf out, bloom, and fruit at precisely the right time for the migrants with which they've co-evolved. Along the edges of your songbird garden, plant shrubs with lots of fall fruit, as well as clumps of nectar-rich flowers for migrating hummingbirds and butterflies. For specific recommendations, see the box above.
In the western states, streamsides and washes are by far the most important habitats for migrating and breeding birds alike. Yet these are among the most threatened habitats in North America. Gardeners and landowners have a major role to play in the restoration of critical floodplain habitats; for details, see "Songbird Gardens for the West" (below).
After the planning and the planting, your songbird hedge will require very little work. In return for the initial effort, you'll get a great deal of pleasure. Unsightly views will be camouflaged. Trespassers will be deterred. Each spring and fall, you'll look forward to the succession of beautiful flowers and fruits. The vireos, warblers, and thrushes arriving at your backyard bed and breakfast will seem like old friends. And you'll have the satisfaction of knowing that you're making life a little less perilous for these songbirds on the move.
Brooklyn Botanic Garden Director of Publishing Janet Marinelli is editor of BBG's renowned series of quarterly gardening handbooks and the author of Your Natural Home and The Naturally Elegant Home. Janet is a champion of the gardener's role in the preservation of the planet, a philosophy that informs her P&G News column, "Down to Earth." It's a philosophy that also serves as the bedrock for her latest book, Stalking the Wild Amaranth: Gardening in the Age of Extinction. In Stalking the Wild Amaranth, Janet tells of her quest for a landscape art that protects disappearing species, both flora and fauna. It's a gardening journey marked by humor—ecologically sensitive gardening needn't be a dreary affair, Janet insists. "We can do our part," she says, "and still have flair and fun."