Do you want more birds in your garden? Choose native plants

Black-headed Chickadees arriving at their seed feeders obtain 20-25% of their food there. There is research to back up the numbers.

These birds have a typical nesting territory of 6 to 10 acres. This is where they first look for food.

If they are not finding the remaining 75-80% of their daily dietary needs from natural sources within that territory, they should look elsewhere. That takes time and energy to raise birds.

The source of the information discussed here is the Ph.D. by Desiree L. Narango. dissertation examining the relationships between birds, insects, and plants. She wrote about the future of conservation and the importance of residential backyards in conservation efforts. Her graduate work was done at the University of Delaware.

One of the villains in this story is Buckthorn, a notorious non-native that is prolific here. Every buckthorn tree, large or small, in a bird’s nesting territory prevents native plants from growing and thriving.

The insects that these birds need to feed their young are not found in the buckthorn, a European species. Our insects and birds evolved with native plants.

It’s pretty simple. Buckthorn and other non-native plants can and will influence the behavior, diet, and population growth of chickadees and other native bird species.

The more non-native vegetation, the fewer birds and species.

Allowing native plants in gardens and patios to be dominated by non-native species is “one of the most pervasive threats to biodiversity today,” Narango wrote.

It doesn’t matter if you plant non-natives or just ignore them, it’s bad either way.

Their study was conducted in Washington, DC, focusing on that area’s chickadee species, the Carolina chickadee. The two species of chickadees share many behaviors and characteristics.

“Native plant groups were more preferred in 97 percent of observed chickadee territories,” Narango wrote. Birds also feed in the trees. In his study, birds foraged most often (28%) in oak trees.

In yards where chickadees were present, non-native plants were avoided as a food source, and chickadees’ plant preferences were highest for native plants that support the most caterpillars, he wrote.

“Homeowners interested in increasing the native bird food available in their yard should… prioritize planting productive native plant species,” he wrote.

In sites dominated by non-native plants, foraging arthropods (insects and spiders) disproportionately selected available native plants, Narango wrote.

Fewer native plants can result in more competition between native insect species for food. It may also mean reduced insect/arthropod populations, he wrote.

Using more native plants can lessen the effect of competition simply by expanding the foraging base. In short, more native plants is better.

He explained that plants described as friendly to wildlife often produce seeds or fruit “long after the breeding season,” when they would be of greater value to birds.

Chickadees avoided breeding in areas with high numbers of non-native plants, even when nesting cavities (always in short supply), their research found. Food for the chicks was apparently a stronger determinant than the opportunity to nest.

“Homeowners who choose to landscap with non-native plants do not provide adequate habitat for species that require an insect diet while breeding,” he explained.

More than 96% of landbird species in North America raise their babies primarily on arthropod prey, he wrote. Insects and spiders provide the quantity and quality of the necessary nutrients.

“In addition,” he wrote, “chickadees are known to lead other bird species to feeding grounds. Thus, the reproductive behavior of chickadees may serve as a model for the relationship between plant quality and bird habitat.” insectivorous birds in general.

His research provides compelling evidence that homeowners should make native plant species a priority in home landscaping. We can improve bird habitat, thereby attracting more birds, by using more native plant species.

More generally, Narango found that a large urban landscape with more non-native vegetation, fewer trees, and more concrete and asphalt had fewer chickadees and fewer breeding chickadees.

Their study included house wrens, robins, gray catbirds, northern cardinals, and house wrens. Generally speaking, these birds did better when feeding on native vegetation.

For native plant species suggestions, visit http://strib.mn/3L9VQ3b or https://bit.ly/39Pk9Gx.

More than half of the world’s population lives in cities and suburbs (Grimm et al., 2008). It is estimated that 80% of our population will live in urbanized areas by 2050 (United Nations Department of Economic and Social Affairs, Population Division, 2019). Bird-friendly gardens will become even more important.

Longtime birder Jim Williams can be reached at [email protected]

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