Bringing Birds Back to Your Yard
It's all about what you choose to plant.
by Richard Conniff
I started out today intending to describe a cool new study on butterflies and the plants they depend on. But as I was filling in the background on the intimate connections between plants and insects, I found myself shifting gears. Developers and homeowners are still adding 500 square miles of ecological desert to the American landscape ever year. Too many of us have yet to discover that our yards—40 million acres of lawns nationwide—can instead be pleasure gardens for us and wildlife, too. So I ended up writing about that, with a few links to help you and your neighbors get started transforming your own yards, your towns, your world.
Smart gardeners these days tend to have little interest in winning the blue ribbon for flawless gladiolas at the county fair. Instead, increasingly, they pride themselves on the bees, wasps, butterflies, and especially caterpillars their gardens attract, and they trade tips on how to attract more of them. It’s a development that would leave gardeners of the last century aghast, clutching their pearls in one hand, and a can of insecticide spray in the other.
People garden for wildlife now because we live in a world where insects, birds, and other wildlife are rapidly vanishing. We garden for wildlife because we have discovered that it’s in our power as individuals to do something to reverse this decline—something that is potentially large-scale and dramatic (but more about that in a moment). It depends entirely on which plants we choose to grow in our yards—and which plants we leave out.
About half of all insects—and 99 percent of butterflies and moths—are plant eaters. They’re seeking nutrition, of course. For adult Lepidoptera, that overwhelmingly means nectar from flowers, with the plants also benefiting because the insects ravishing their flowers are incidentally spreading their pollen, helping them to reproduce.
The plants help the insects reproduce, too, though that’s more of a one-sided transaction. Butterfly and moth species have typically adapted to use certain key plant species as hosts on which to deposit their eggs. When their caterpillars emerge, they feed on the plants.
The link between a plant species or genus and its associated insects is often the result of co-evolution over tens of thousands of year, or more. So plants evolve biochemicals—essentially pesticides—to protect themselves from being nibbled to bits by very hungry caterpillars. Some insects species have in turn evolved so their caterpillars can extract these pesticides, which then then become repellents and attractants for the insect.
Monarch caterpillars, for instance, consume toxins—cardiac glycosides—from any of the 130 milkweed species in the genus Asclepias, and those foul-tasting toxins then protect the adult butterflies from predators. Milkweed (genus Asclepias) is the monarch caterpillar’s only host plant. So the disappearance of milkweed from yards, farms, and spare corners of the industrial landscape (hello, lawncare! hello, herbicides!) is the main reason monarchs are now an endangered species. It’s much the same story for other insect species that struggle to find their associated plants in a landscape now almost entirely given over to Kentucky bluegrass, fescue, and other forms of grass.
Doug Tallamy, a University of Delaware entomologist and author, has spent much of his career detailing just how directly beneficial insects depend on the presence of certain key plant species—and also how that connection makes a life or death difference for other species. What really stunned me in his 2019 book, Nature’s Best Hope, were the details about how completely our familiar birds depend on the presence of native plants and insects at breeding time.
A pair of nesting Carolina chickadees, for instance, must bring 350 to 570 caterpillars home daily to feed their rapidly growing offpring, or 6000-9000 caterpillars over the 16 days it typically takes from hatching to fledging. They find those caterpillars overwhelmingly on native plants, because butterflies and moths don’t lay their eggs on non-native plants their ancestors never laid eyes on—rhododendrons from the Himalayas, for instance, or boxwoods from Europe.
That same nesting chickadee pair typically does their foraging in an area of about two acres. So let’s say you live in a development of quarter-acre lots, that means it might take as few as eight neighboring properties to support one chickadee nest. But if those eight yards are 80 or 90 percent lawn—typical in many suburbs—and if the developer has “beautified” the rest with non-native (and invasive) Bradford pears, burning bush, barberry, and the like, don’t expect chickadees to be at home there. It’s the same for other desirable bird species.
The way to restore wildlife, Tallamy proposed in Nature’s Best Hope, is to bring back the native plants. Replace that Bradford Pear with a willow or a birch. Plant asters because 109 caterpillar species call these beautiful flowers home. Make room for lupines, which send up a tall cone of beautiful flowers, and in my neighborhood serve as host plants for 26 butterfly and moth species. For those with the acreage, plant oaks, cherries, and other native trees known to be insect-friendly. Instead of just putting out a feeder to attract birds, make your yard a bird feeder.
Does it work? Tallamy describes how Chicago resident Pam Karlson has transformed a tenth of an acre of yard hemmed in between the runways of O’Hare International Airport and the Kennedy Expressway. Over a quarter century, she has planted and nurtured 60 native plant species, including serviceberry, green hawthorn, a silver maple, and a row of northern white cedars. As a result, she has logged 103 species of bird there, including even a woodcock, normally a forest inhabitant. Karlson’s “favorite time of day,” Tallamy writes, “is late afternoon happy hour in her yard, when she unwinds with binoculars, her camera, and a glass of wine.”
Let’s say you tried something like that. Would it really make any difference? If every American landowner made it “a goal to convert half their lawn to productive native plant communities,” Tallamy writes, it would restore 20 million acres of habitat, creating a “Homegrown National Park” bigger than our entire existing national park system.
Start by reading the book, which you can find at many local libraries, or buy at your local independent bookstore. Look for groups in your town working to do the sort of transformation Tallamy is proposing. If no group exists, start your own.
Lists detailing specific plants and the insects dependent on them are available online for every region of the country, from the Xerces Society, the invertebrate conservation group. Tallamy, together with the National Wildlife Federation, also has a Native Plant Finder online, organized by zip code. For additional resources and seasonal recommendations, sign up for Rebecca McMackin’s Grow Like Wild newsletter. (If you have other helpful suggestions, please add them in the comments below.)
Plan on spending half as much time behind a lawnmower. Instead, spend that time sitting in the cool of the shade, sipping your ice tea (substitute beer, cocktail, mocktail as needed) and watching the birds and butterflies you’ve invited back to their old home.
That’s it for now. With apologies, I’m visiting with my new grandson right now, and a little distracted. So in lieu of the piece about that new study I meant to write about, here’s a video.