Bringing Nature Home: How You Can Sustain Wildlife with Native Plants

by Douglas W. Tallamy

If our native insect fauna cannot, or will not, use alien plants for food, then insect populations in areas with many alien plants will be smaller than insect populations in areas with all natives. This may sound like a gardener’s dream: a land without insects! But because so many animals depend partially or entirely on insect protein for food, a land without insects is a land without most forms of higher life

If you count all of the terrestrial bird species in North America that rely on insects and other arthropods (typically, the spiders that eat insects) to feed their young, you would find that figure to be about 96 percent (Dickinson 1999)—in other words, nearly all of them.

Insects are essential. Nearly all terrestrial birds rear their young on insects, not seeds or berries.

It is curious that the news media have drawn our attention to the loss of tropical forests yet have been silent when it comes to how we have devastated our own forests here in the temperate zone. Only 15 percent of the Amazonian basin has been logged, whereas well over 70 percent of the forests along our eastern seaboard are gone (Brown 2006).

As of 2002, Delaware had lost 78 percent of its freshwater mussel species, 34 percent of its dragonflies, 20 percent of its fish species, and 31 percent of its reptiles and amphibians. Moreover, 40 percent of all native plant species in Delaware are threatened or already extirpated from the state, and 41 percent of Delaware’s bird species that depend on forest cover are now rare or absent (Vargo & Gallagher 2002; Hess et al. 2000).

For those who would like birds in their future, the statistics are truly frightening. Neotropical migrants, such as wood thrushes, warblers, catbirds, hawks, wrens, vireos, flycatchers, kingbirds, nightjars, swallows, tanagers, orioles—species that fly thousands of miles to Central or South America to spend the winter—have declined an average of 1 percent per year since 1966 (Sauer, Hines & Fallon 2005). Add up those percentages, and you’re looking at nearly a 50 percent reduction in population sizes for many of our bird species within the space of 50 years.

3BillionBirds.org #BringBirdsBack (For a recent report on the decline of birds published in 2019) A world without birds is a very real possibility.

The World Conservation Union has estimated that 12 percent of all bird species are threatened with extinction because of habitat loss and invasive species. Conservation ecologists such as Cagan Sekercioglu of Stanford University believe that one fourth of all bird species will be functionally extinct (that is, so rare that they no longer contribute to the function of ecosystems) within a century (Sekercioglu, Daily & Ehrlich 2004).

3BillionBirds.org #BringBirdsBack

We are losing our birds because we have taken away their homes and their food and filled their world with dangerous obstacles that take a terrible toll. Remember those 4 million miles of U.S. roads? Vehicles using them flatten birds daily, resulting in 50 to 100 million deaths per year (U.S. Fish & Wildlife Service 2002). Then there are buildings along the roads—often tall and always window-filled buildings. Each year as many as 1 billion birds are killed when they fly into the windows of those buildings (Klem 1990).

Scientific consensus is that our native birds are in deep trouble, and we are going to have to improve their habitats quickly if they are to survive at all.

The U.S. has more birds than ever before, naysayers claim. What they don’t mention is that the birds they are counting are European starlings and House sparrows, both invasive species from Europe.

we have taken and modified for our own use between 95 and 97 percent of all land in the lower 48 states.

When extinction adjusts the number of species to the land area that remains for the plants, mammals, reptiles, birds, and invertebrates of North America (something that will happen within most of our lifetimes), we will have lost 95 percent of the species that greeted the Pilgrims.

Unless we modify the places we live, work, and play to meet not only our own needs but the needs of other species as well, nearly all species of wildlife native to the United States will disappear forever.

This is not speculation. It is a prediction backed by decades of research on species-area relationships by ecologists who know of what they speak. And the extinction of our plants and animals is not a scenario lost in the distant future. It is playing out across the country and the planet as I write. Our preserves and national parks are not adequate to prevent the predicted loss of species, and we have run out of the space required to make them big enough. For conservationists, and indeed for anyone who celebrates life on earth, this is perhaps the direst possible consequence of the human enterprise.

I have heard four answers to queries about the need for biodiversity. The first is that we don’t need it. In fact, many people would argue that efforts to preserve biodiversity have caused nothing but roadblocks and headaches for economic development.

It disgusts me that there's people who think we don't need nature at all. Just buildings and pavement and cars....nothing but noise and no peace. It's depressing.

Even though the number of plant species present in the area is higher by one, the ecological interactions that drive the Everglades ecosystem have collapsed where Melaleuca has invaded because its dominance contributes nothing to other organisms. Diversity is important, then, only when the species that can be said to create it are contributing members of their ecosystem. This contribution is most likely when species have evolved together over long periods of time.

The grassland birds that breed in the Everglades cannot nest in Melaleuca groves, and they find fewer insects to eat because native insects cannot eat Melaleuca leaves (Costello et al. 1995). Alligators cannot make their wallows or find food in Melaleuca groves, and so they have lost hundreds of thousands of acres of habitat. Butterflies cannot find their host plants, egrets cannot hunt the fish they eat, and hummingbirds cannot find the nectar they need to survive from day to day.

Lesions from the fungus Cryphonectria parasitica were first found on an American chestnut tree at the Bronx Zoo in 1904. Within 50 years, Castanea dentata, the dominant upland forest tree species from Maine to Mississippi—a tree that had previously survived an asteroid impact and at least 20 glaciations during its 87 million years of evolutionary history (Willis & McElwain 2002)—was functionally eliminated from the eastern deciduous forest ecosystem.

There are dozens of examples of plant diseases that were inadvertently brought to our shores with nursery stock, but none has been more devastating to our eastern deciduous forests than the chestnut blight. The chestnut blight is of Asian origin and was transported to the Northeast in 1876 on Castanea crenata, resistant Japanese chestnut trees for ornamental trade.

Castanea dentata was the primary nut producer of eastern forests, dwarfing the contributions of oaks, beeches, and hickories as wildlife food sources. Squirrels, chipmunks, deer, elk, black bears, turkeys, passenger pigeons, doves, blue jays, and mice were just some of the animals that depended on copious quantities of chestnuts to make it through long winters. Equally important but more poorly documented was the role American chestnuts played in producing insects that supported huge populations of songbirds. Castanea dentata is a member of the plant family Fagaceae, which supports hundreds of species of caterpillars and other insects eaten by birds. The niche vacated by chestnut trees was slowly filled with other tree species (Cech 1986), and our forests appear today as though nothing had happened—unless you compare the density of wildlife that forests support today with what they used to support.

Such a study is now impossible, not only because the chestnut is gone—along with an unknowable number of insect specialists that ate only the chestnut—but also because our forests are now so fragmented.

As if to mock our attempts to keep these foreign creatures from entering our country on nursery stock, a second species, the balsam woolly adelgid (Adelges piceae), has all but eliminated the Fraser fir (Abies fraseri) from the high altitudes of the Great Smoky Mountains National Park (Amman & Speers 1965). This insect was brought to New England from Europe in 1900 and then was moved on nursery firs to North Carolina in the 1930s. Because Fraser firs are endemic to the Smokies (found nowhere else in the world), their loss from the area is equivalent to their extinction).

There is no debate when we close our borders to carriers of human diseases like SARS, mad cow disease, and avian flu virus. Why are the native plants that sustain us and our native animals less worthy of protection?

To date, over 5000 species of alien plants have invaded the natural areas of North America.

And this accounting does not even begin to number species that stowed away as seeds or small plants in the soil surrounding the sought-after ornamentals.

Even our most pristine national parks are under attack. The Great Smoky Mountains National Park, for example, has been invaded by over 300 species of alien plants (Miller 2003).

In many areas of the East, aliens are blocking succession completely. Fields that were released from agriculture 25 years ago should have become young forests 30 feet tall by now; instead, they are impenetrable thickets of alien vines, and I don’t see them ever escaping their alien blanket without human intervention.

A field rich in goldenrod, Joe-Pye weed, boneset, milkweed, black-eyed Susan, and dozens of other productive perennials supplies copious amounts of insect biomass for birds to rear their young. After it has been invaded by autumn or Russian olive, that same field is nearly sterile.

By favoring native plants over aliens in the suburban landscape, gardeners can do much to sustain the biodiversity that has been one of this country’s richest assets.

A plant that has fed nothing has not done its job

if you delight in a golden-crowned kinglet foraging in your oak tree or an indigo bunting singing from a perch in the middle of your goldenrod patch, you may also find pleasure in the exquisite beauty of the insects that your native plants produce. Creating habitats specifically for particular insect species can be its own reward and will connect you to a fascinating part of nature that most people never meet.

By and large, people know next to nothing about the most diverse group of organisms ever to evolve, and what they do know comes from negative encounters with a few species of biting flies, “dirty” roaches, wasps with painful stings, or crop-devouring caterpillars. Our nearly universal animosity toward insects is understandable, but seriously misplaced. Of the 4 million or so insect species on earth (to put things in perspective, there are only about 9500 species of birds), a mere 1 percent interact with humans in negative ways. The other 99 percent of the insect species pollinate plants, return the nutrients tied up in dead plants and animals to the soil, keep populations of insect herbivores in check, aerate and enrich the soil, and as I keep stressing, provide food either directly or indirectly for most other animals. John Losey and Mace Vaughan (2006) have valued the ecosystem services provided by insects at $57 billion each year. As E. O. Wilson (1987) has pointed out, insects have done fine on this earth without humans and would continue to do so in our absence. If insects were to disappear, however, our own extinction would not be far behind. It may be hard to admit, but we need healthy insect populations to ensure our own survival.

Planting butterfly bush in your garden will provide attractive nectar for adult butterflies, but not one species of butterfly in North America can use buddleias as larval host plants. To have butterflies, we need to make butterflies.

Butterflies used to reproduce on the native plants that grew in our yards before the plants were bulldozed and replaced with lawn. To have butterflies in our future, we need to replace those lost host plants, no if’s, and’s, or but’s. If we do not, butterfly populations will continue to decline with every new house that is built.

Instead of building a butterfly garden with aliens that will make no new butterflies, use a native species that serves as a host for butterfly larvae as well as a supply of nectar for adults. This requires some knowledge, because butterflies do not lay their eggs on any old plant. They...

One excellent group of plants that no butterfly garden should do without are the milkweeds (Asclepias). When planted together, milkweed species such as butterfly weed (A. tuberosa), common milkweed (A. syriaca), and swamp milkweed (A. incarnata) create a continuous display of wonderful pink or orange flowers that are highly attractive to several species of butterflies from June into September. Moreover, along with the floral show, you get brand new butterflies. The monarch (Danaus ...

Monarch larvae develop only on milk-weed species.

This can't be stated enough. The Monarch Butterfly population has plummeted dramatically. It doesn't matter how many flowers we plant for the adults to visit, if there's no milkweed plants they can't reproduce.

Coneflowers and black-eyed susans (Rudbeckia species) also wear two hats in the butterfly garden. Along with their attractive floral display and nectar, rudbeckias support the reproduction of dozens of species of Lepidoptera, including the pearl crescent (Phyciodes tharos), silvery checkerspot (Chlosyne nycteis), and wavy-lined emerald (Synchlora aerata).

Buttonbush (Cephalanthus occidentalis) is another of my favorites for the butterfly garden. Its ball-shaped flowers capture the eye, it does well in wet areas, butterflies fight to gain access to its nectar, and it serves as a host plant for 18 species of Lepidoptera in my neck of the woods. These include the ethereal promethea moth (Callosamia promethea), the hydrangea sphinx (Darapsa versicolor), and the saddleback caterpillar (Acharia stimulea).

For a tall display of pink billowy flowers, use common Joe-Pye weed (Eupatorium dubium) or hollowstem Joe-Pye weed (E. fistulosum). These species are every bit as attractive to nectaring butterflies as butterfly bush, and they host over three dozen species of Lepidoptera.

If you want mourning cloaks (Nymphalis antiopa), viceroys (Limenitis archippus), or io moths (Automeris io), plant what they eat as larvae—any of our many native willows—and you will have them.

If you want to enjoy tiger swallowtails (Papilio glaucus), plant tulip trees, sweetbay magnolia, or black cherry trees. Black cherries will also provide food for red-spotted purples (Limenitis arthemis astyanax) and over 400 other moths and butterfly species.

Eupatorium species are a wonderful nectar source for butterflies like the tiger swallowtail and spicebush swallowtail, and they also provide food for the larvae of more than three dozen species of Lepidoptera.

If you plant buttonbush, alternate leaf dogwood, birches, willows, or black cherry in your yard, you may attract the spectacular cecropia moth (Hyalophora cecropia).

Fritillaries eat violets (Viola), which can make a lovely ground cover for your butterfly garden.

Virginia creeper will enable the majestic Pandora sphinx to reproduce (by contrast, English ivy, the vine of choice in suburbia, hosts nothing).

Oaks will provide food for the polyphemus moth (Antheraea polyphemus) and the bizarrely attractive larvae of moths in the family Limacodidae.

Sweet gum (Liquidambar styraciflua) is your best bet for the luna moth, and it’s easy to remember that the spicebush ...

The diminutive spring azure (Celastrina ladon), one of the first butterflies to become active as the days warm in the spring, may become a resident of your yard if you plant flowering dogwood (Cornus florida) or any of our native Viburnum species. They won’t appear if you insist on kousa ...

If you take the time to enter their world, even for a little while, these tiny marvels will not only enrich your garden, they will enrich your life as well.

Until the political will to protect the monarch’s forests materializes, the only hope for this species is to make sure that those butterflies that do survive the winter reproduce successfully—and hugely—when they return to your backyards each summer.

The more food provided in the form of milkweed plants, the greater the number of monarchs produced.

We lose much when we remove leaf litter because it provides so many free services for us: free mulch, free fertilizer, free weed control, and free soil amendments. Litter also provides habitat for many of the arthropod predators that help keep garden communities ecologically balanced. Above all, a deep bed of leaf litter acts like a sponge, soaking up enormous quantities of water during downpours. Without litter, rainwater typically flows off our properties and into the gutters, flooding streams, rivers, and occasionally our homes. When the rain stops, leaf litter that has been allowed to accumulate slowly releases its moisture, keeping the plants and trees in your garden well hydrated, even during dry periods. Bare ground (or lawn) does none of this.

Your leaf litter can be home to a rich assortment of native plants while it is fertilizing, mulching, and watering your land. Many wildflowers grow only in soil with lots of humus, including pink and yellow lady slippers, trout lilies, bloodroot, Solomon’s seal, Jacob’s ladder, Jack-in-the-pulpit, numerous species of ferns and trilliums, mayapples, wild ginger, dwarf crested iris, and foamflower.

If you are concerned about the human impact on our planet’s climate, reducing the amount of lawn you mow each week is one of the best things you can do to reduce your family’s carbon dioxide emissions. On average, mowing your lawn for one hour produces as much pollution as driving 650 miles. Moreover, we now burn 800 million gallons of gas each year in our dirty little lawnmower engines to keep our lawns at bay. In all we spend $45 billion each year on lawn care (Holmes 2006).

Converting lawn to trees or garden would not only save us some money and create much needed food and habitat for our wildlife, but it would also have the twofold benefit of producing less and absorbing more carbon dioxide: a win-win endeavor.

Bradford pears are cheap and mass-marketed. Unfortunately, they are also invasive species toxic to wildlife that try to eat them. How much better for wildlife if the developer had planted oak, beech, basswood, sweet gum, black gum, red maple, sycamore, or one of the stately hickory species. All of these can be wonderful specimen trees.