In recent years, the push to plant natives has been all the rage, and if your client is a bird-lover, there is new research providing even more support for native plants.
One of the commonly cited reasons for homeowners to install native plants is because it helps the local wildlife, including pollinators and birds, as they have evolved and adapted to the same region together. Often natives have more insects or yield more fruit than non-native plants.
Doug Tallamy published his work showing how native plants tended to host far more caterpillars and yards with more native plants saw more native-bird species, but until now there hadn’t been any studies to see how this research linked with a specific diet of a bird.
Research published in Biological Conservation found that native vegetation does in fact provide more food for nesting birds than introduced plant species. In a two-year study of Carolina Chickadees around Washington, D.C., scientists were able to connect what plants the songbirds were using for their food source.
“Quantifying insects as bird food is difficult,” Desiree Narango, the University of Delaware student who led the research, told the National Audubon Society.
The team started by determining the origin of each tree and shrub species at the 97 suburban homes they selected. Then they checked the leaves of 16 plants at each site, counting the caterpillars. They then tracked which vegetation had the most visits from chickadees.
Narango found from the data that the chickadees nested more often in yards with native trees. Oaks, cherries, elms and maples were some of the most popular as they attracted the most moth and sawfly larvae, which birds depend on for feeding their chicks.
Previous studies have found that chickadees need around 6,000 to 9,000 caterpillars a season to feed a brood of five babies.
“Carolina Chickadees are a model species because they’re generalist foragers,” Narango told Audubon.
Because chickadees look almost anywhere for food, they tend to serve as a good rule of thumb as to where other songbirds might gravitate towards. Non-native flora was found to have one caterpillar or fewer on them while natives like oaks harbored 20 or more.
In Tallamy’s research, he found that natives can support multiple species with some oaks maintaining 557 species of moths and butterflies, while others like wild cherry and plum trees can support up to 456 species. While non-native relatives to these plants support wildlife food sources, there aren’t nearly as many and introduced species are even less productive.
“Eight-six percent of the country is privately owned, so when you create landscapes out of [introduced] Bradford pear and crape myrtle, there are almost no caterpillars,” Tallamy said. “That’s not just the end of reproduction for chickadees, but of all the birds out there that need those insects.”
While the study is designed to help educate people about the need to make more informed planting choices, one of the biggest struggles is finding natives to buy.
“When I go looking for plants I know birds use, I can’t find them either as seed or seedling,” said Roarke Donnelly, director of the environmental studies program at Oglethorpe University. “I don’t think growers know there’s a burgeoning demand for this. We have to hook them up with residents – there’s huge potential.”