If you have a Carolina chickadee nest in your yard, it's a clue that you’re doing your part to preserve nature. What's the connection? Well, first you have to understand what chickadees like to eat.
These inquisitive little birds with the black caps are year-round residents in a large swath of the central and eastern sections of the country — from the Atlantic to the middle of Texas and from southern Indiana, Illinois and Ohio to the Gulf Coast and Central Florida. When the birds are breeding, caterpillars are the only food they eat and feed their young.
Caterpillar hunts are a daily ritual for breeding pairs, which begin their work at dawn and continue until dusk. During three hours of observation, Doug Tallamy, professor of Entomology and Wildlife Ecology at the University of Delaware, saw adult birds return to their nest once every three minutes with a caterpillar. In all, he wrote in his notes, they found and brought back 17 species of caterpillars.
The females produce a clutch of three to six eggs with the babies remaining in the nest for 16-18 days. Do the math, Tallamy says. With the parents feeding their young every three minutes from 6 a.m. to 8 p.m., that’s between 390 and 570 caterpillars a day — or anywhere from 6,240 to 10,260 caterpillars until the young fledge. And once the babies have left the nest, the parents will continue to feed their young for several days, he says.
"You can’t have nesting Carolina chickadees if you don’t have enough host plants to support caterpillar populations," Tallamy says.
A lack of native plants is proving to be detrimental to Carolina chickadees and other birds. A Smithsonian study links the decline in "common resident bird species" to lack of insects due to nonnative plants used in landscapes and gardens. Researchers stated that only home gardens that had at least 70 percent native plants are able to feed enough chickadees to produce a stable population for that area.
"Landowners are using nonnative plants in their yards because they’re pretty and exotic, they’re easy to maintain, and they tend to have fewer pests on them," said Desirée Narango, a graduate student researcher at the Smithsonian Conservation Biology Institute and first author of the study. "But it turns out that a lot of those insects they see as pests are actually critical food resources for our breeding birds. For landowners who want to make a difference, our study shows that a simple change they make in their yards can be profoundly helpful for bird conservation."
Bugs and native species
Chickadees are just one example of birds that depend on insect larvae, as Tallamy points out in his book "The Living Landscape," which he created with co-author and photographer Richard Darke. A red-bellied woodpecker that weighs eight times more than a chickadee also feeds its young on insect larvae, Tallamy says.
"And it’s not just birds that need insect biomass," Tallamy adds. “Spiders, frogs, toads, lizards, bats and even rodents, foxes and bears all need insects and the larval host plants that support them to survive.”
By host plants, Tallamy means native species. Planting natives, he says, is the way to save nature. And he wants American homeowners to know that saving nature begins in their yards.
Our yards are ground zero because planting home landscapes with native species is the only remaining way to re-create once-connected natural ecosystems that have been disrupted by commercial development and urban sprawl.
"Amazingly enough," he says, "our natural areas — parks, preserves and even our largest national parks — are no longer large enough to support the nature we all need to run our ecosystems. We’ve shrunk them down too far. We’re now at a point where we cannot lose the insects in our yards without collapsing local food webs."
A tool for improving any habitat — including your backyard
Tallamy is on the board of a team that has devised an online tool to bring together people interested in rethinking their yards. Housed at the Cornell Lab of Ornithology at Cornell University in Ithaca, New York, and jointly run with The Nature Conservancy, the tool is a citizen science project called Habitat Network.
Habitat Network, which is built on Google Maps, provides homeowners with an easy and interactive way to record small-scale natural habitats on their property. Using the map involves four basic actions:
1. Outlining the site
2. Adding ecological details
3. Drawing habitat
4. Placing objects, like special trees or bird baths.
The project gives homeowners a place to learn about wildlife landscaping without incurring major expenses such as the cost of hiring a landscape designer. Special smart tools, such as the Local Resources page, provide access to the expertise and resources you will need to create your own sustainable habitat, taking into consideration everything from the tiniest insects to the largest existing trees or those you want to plant.
"Creating a wildlife habitat from a typical yard is a journey," says project leader Rhiannon Crain. "It isn't something that happens overnight. Habitat Network is meant to help people start that journey, and support them as they make decisions about changes along the way. It is also a tool for recording those changes as they happen. This becomes data for our scientists who have questions about how well yards can act as safe habitat for birds."
You begin by using simple drawing tools to create a map of your entire property, including hardscapes, such as buildings and driveways, and existing vegetation. Because the map is interactive, if you’re uncertain what type of tree or shrub is already on the property you can post of a photo of it and see if a Lab of Ornithology scientist or another user can identify it. Then, the fun starts.
You can browse other people’s maps, including carefully selected featured sites to start planning your own changes. You can also look up local experts using the ZIPcode-based local resources tool, find nurseries that carry native plants, talk to others, and even link-up to eBird, a bird monitoring project to start recording the birds you see in your yard. Then, over time, as you change your yard (for example by planting a new native, decreasing the size of your lawn, or putting up a new bird bath), you can return to Habitat Network to edit your map.
The scope is not limited to home landscapes. It can also be used to create natural areas at neighborhood schools, in around office buildings, or in public areas. "The project is really catching on," Crain says. "We've had more than 20,000 people create accounts and there are almost 12,000 maps in our database. New users certainly won't be alone, there is a whole quiet revolution going on in people's yards, and we want to document it, share it, and make sure everyone is invited to the party."
Choosing plants carefully
As you choose plants for your landscape, Tallamy suggests keeping the lawn as small as possible. Essentially, he said, decide where your "traffic" areas are for walking through your yard and turn everything else into natural areas. In those areas, he suggests planting in vertical layers beginning with a floor of ground covers, moving up to woody shrubs that keep their stems in the winter and then on to a "ceiling" of trees and their overhanging branches.
And he says, don’t make a mistake he often sees in residential landscapes. "Most people think the plants you need to attract birds are only plants that produce seeds and berries," he said. That’s not the case.
"Insects are such specialists," he said, "that 90 percent of them will only eat and reproduce on plants with which they have an evolutionary history." He cites milkweed, red cedar, junipers, sycamores, beeches, and oaks as examples. "This specialization is a curse because we are eliminating these plants from our landscapes."
Another mistake is planting with non-natives. “You’ll actually starve birds by filling your landscape with plants such as crape myrtles,” Tallamy says, pointing out these flowering trees are native to the Indian subcontinent, Southeast Asia and parts of Australia and do not support the caterpillars that sustain local food webs.
Tallamy is a realist and accepts that homeowners aren’t going to limit plant selection for their landscapes to just natives. "You can still have crape myrtles,” he says. “But if 80 percent of your woody plants are Asian introductions, you’re not playing the game. Homeowners need to accept that their property is part of a local ecosystem and each of us has to accept that we have a role to play."
When we do that, Tallamy believes, our neighbors will not only take notice but take action. When the neighbors follow our lead, then the thinking is that communities can create the type of connected ecosystems that are possible when one backyard after another is converted into a natural habitat.
"Homeowners need to create natural areas in their yards not because natives give us a sense of place, or because they are prettier, or for nostalgic reasons, or because we oppose change or because we don’t like foreigners," Tallamy says. "We need to plant natives because they create a functioning ecosystem."
If you embrace Tallamy’s concept, how can you tell if you’re succeeding in making a positive impact? It’s when you stop thinking of holes in leaves as insect damage, Tallamy said. Or, when you see fireflies in the evening. Or you see a female chickadee building her nest.
Editor's note: This article has been updated since it was originally published in March 2015.