By Michele S. Byers
Your yard may be your neighbors’ envy … beautifully landscaped and well maintained, but if it’s full of non-native plants, to birds it’s a parched desert.
A recent study by the Smithsonian Conservation Biology Institute found that birds who need high-protein insects often go hungry in yards landscaped with non-native plants. As a result, populations of common backyard birds and even migratory and endangered birds may decline.
The Smithsonian studied Carolina chickadees, a common bird that that lives as far north as south and central New Jersey. The study found that reduced food – especially fewer caterpillars – is leading to a decline in the breeding success and population of Carolina chickadees.
“Landowners are using non-native plants in their yards because they’re pretty and exotic, they’re easy to maintain and they tend to have fewer pests on them,” explained Desirée Narango, the main author of the study published in “Proceedings of the National Academy of Sciences.”
“But it turns out that a lot of those insects they see as pests are actually critical food resources for our breeding birds,” Narango explained. “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.”
According to the Smithsonian, the study is the first to directly link the decline of common backyard birds to a lack of insects from the use of non-native plants.
The researchers placed nest boxes in more than 160 yards in the Washington, D.C., metropolitan area. Homeowners monitored the nest boxes weekly for Carolina chickadees, eggs and nestlings. They also tracked individually marked chickadees to help researchers determine adult and juvenile survival rates.
As it turned out, the only yards that produced enough chickadees to sustain a stable population were those with more than 70% native plants.
The study notes that because more than 90% of plant-eating insects are “specialists” – meaning they will only feed on one or a few specific plants – using a variety of native plants in landscaping is essential to making sure birds have enough insects to eat. Monarch butterflies are a good example of specialists, as monarch caterpillars eat only milkweed plant leaves.
The researchers believe native plants are probably just as critical for other resident birds, migratory birds and endangered birds … in backyards everywhere, not just on the East Coast.
Narango pointed out that “artificial suburban landscapes” are found all across the United States: “A gingko that you plant in D.C. and a gingko that you plant in L.A. are doing the same thing for bird conservation — nothing.”
The study urges homeowners to switch to native plants, which will provide more food for common North American birds, as well as food and resting habitat for migrating birds.
What natives should you plant in your yard?
New Jersey native plants that support birds include: Flowering dogwood, white fringetree, persimmon, American holly, spicebush, serviceberry, Eastern columbine, butterfly weed, purple coneflower, beebalm, cardinal flower, black-eyed Susan, Virginia bluebell and wild geranium.
There’s lots of information to help you identify the native trees, shrubs and wildflowers that will grow best on your property.
The Jersey-Friendly Yards website – www.jerseyyards.org – includes an extensive plant list and an online tool to design a landscape plan. You can find hundreds of trees, shrubs and flowers that are native to New Jersey.
The website’s “Interactive Yard” tool provides step-by-step instructions for making your property the healthiest possible environment. For instance, it gives advice on removing impervious surfaces, getting rid of invasive plants, adding plant beds around the house, harvesting rainwater, attracting pollinators and starting a vegetable garden.
The National Audubon Society also has a native plants list at www.audubon.org/native-plants. Enter your zip code on the site to get recommendations for natives that grow well in your region, and a list of birds that each plant may attract.
More help comes from the Native Plant Society of New Jersey, which offers illustrated lists of plants that support birds and native wildlife at http://www.npsnj.org.
Please landscape your property for the birds! And to learn more about preserving land and natural resources in New Jersey, visit the New Jersey Conservation Foundation website at www.njconservation.org or contact me at [email protected].
Michele S. Byers is the executive director of the New Jersey Conservation Foundation in Morristown.