by Caitlyn Johnstone
February 24, 2021
Imagine you’re a bird in early spring, when the world wakes up and buds appear on trees. You flap your wings in a light, warm breeze as you go in search of food. You enjoy seeds and berries, but instinct and evolution drive you to seek richer food for your hungry babies—fat and juicy caterpillars, protein-packed beetles, nutrient-rich spiders and other healthy bugs. Each year, you gather insects in the thousands to help your babies grow—but lately, you’re having trouble finding food.
The decline in birds and insects is tied to the need for native plants
Baby birds cannot exist on seeds and nuts the way adult birds do; hatchlings require the richer nutrients found in insects—a lot of them. Chickadees—those plump, almost round little birds that are a favorite at feeders—require 6,000 to 9,000 caterpillars to raise just one clutch of babies. Meanwhile, those caterpillars are very particular about the plants they will eat. Therefore, the adult butterflies and moths will only lay eggs on and around those specific host plants. If we want birds, we need caterpillars, and to have caterpillars, we need the right plants. Native ones.
Certain native species, like oak trees, support hundreds of species of moths and butterflies, while several popular—but invasive—plants and trees may support just ten, or two or zero. More and more research indicates a precipitous drop in insects, which is starting to show in the decline of birds. One of the major stressors impacting the food chain lies in how humans are changing the plant landscape. Insect ecology professor and backyard conservation expert Doug Tallamy puts it in simple terms: “When you create landscapes out of [introduced] Bradford pear and crape myrtle, there are almost no caterpillars. That’s not just the end of reproduction for chickadees, but of all the birds out there that need those insects.”
Monarch butterflies are a great example of this interplay between flora and fauna: though adult monarchs need to feed on the nectar of many native flowers, these beautiful butterflies lay their eggs only on milkweed plants. Without milkweed plants, there will not be monarch butterflies. Most other butterflies also have specific host plants where they lay eggs, yet humans don’t always understand that they must create a biodiversity of native plants to support the biodiversity of caterpillar species needed by our backyard birds. As Tallamy puts it, “There are millions of people who put out bird food all winter long, and during the summer they starve the birds by the way they landscape.”
States on the sale of invasive plants
We can repair the food web not only by supplying more native plants, but also by reducing invasive plants. “Invasive” is a term used to differentiate harmful non-natives that cause damage to the ecosystem from those that are simply not native to the area. Typically, a non-native plant is considered “invasive” when it outcompetes other species native to the region, allowing it to dominate the landscape and siphon resources. Nonprofits, businesses, local governments and state agencies spend millions of dollars each year trying to control invasive species, many of which can be bought in little pots at your local store.
Plants categorized with the regulatory term “noxious weed” are historically those affecting agriculture and have long been illegal to sell, but plenty of invasive species that affect the wider ecosystem remain on the market. Plants that are commercially viable (popular for sale) are sometimes exempted from weed listings, which allows many invasive plants to be sold at nurseries or large stores. States are trying to correct this disconnect, drafting legislation that will put the listing of species into the hands of ecological experts.
In the state of Maryland, any invasive species sold must be marked with signage that identifies them as an invasive plant. In 2021, Delaware passed a bill to prohibit the sale of plants identified by the Secretary of the Department of Agriculture, with the advice of the Delaware Native Species Commission, as invasive. In the Commonwealth of Virginia, a joint resolution passed this session to convene a workgroup that will offer recommendations on promoting native plants and reducing the sale of invasive plants.
Plant nurseries leading the way
While regulations can take time, plant nurseries are making changes on their own and cementing their role as plant professionals through their partnerships with experts. In Maryland, nurseries like Chesapeake Natives are educating customers on gardening with native plants. In New York, North Creek Nurseries recently announced it was eliminating the sale of the ornamental grass Carex flacca on the recommendation of botanist Dr. Robert Naczi of the New York Botanical Garden. At the bottom of the notice, three similar native species are showcased as alternatives, with links directly back to the plant’s profile page on the nursery’s website. “It has not hurt us to drop these items,” reads North Creek’s statement. “In fact, it has increased the trust we build with you, our customers. It gives us the ability to ‘do the right thing’ and stand behind our principles. We learn, we course-correct and we grow. That said, as plant propagators, we rely on experts to provide us with the knowledge and science.”
Want to make a difference?
Most of the land in the United States is privately owned, so individual people are on the front lines of saving birds, bees and native trees.
- Do not buy invasive plants. Demand drives sales and as consumers, people have power. Stop making invasives into best sellers.
- Be an informed plant parent. Learn to recognize native and invasive plants.
- Turn your backyard into a pollinator and songbird habitat. Remove any invasives currently growing in your yard and plant natives in their place.
- Plan ahead. If you are planning yard changes or beginning from scratch, design for natives right from the start.
- Help educate, kindly. Many people are not aware of the intricate ties in our ecosystem, or that their plant choices can make a difference. Share what you know with your neighbors in a friendly way, and entire communities may become more welcoming to birds and bugs.
- Communicate. Native plants are not as familiar as nonnative garden choices, so fully native gardens tend to stand out as unusual. Make a point to tell your neighbors what you are doing and why. Consider installing a helpful sign explaining the benefits of a native garden with passersby.
We all have influence in more than our own yards. Look at the grounds of your work, your meeting places and your hometown public spaces. Do you see native plants? If not, offer some options for more ecologically friendly plant choices. Together, humans can help shape a plant world that is both beautiful and beneficial.