Native trees — species that are native to a particular geographic area — help protect water quality through their deep, well-adapted root systems that naturally increase the ability of soil to absorb, treat and retain water. These trees are also essential for supporting our region’s diverse bird populations. Native trees produce more insect prey for birds than non-natives ― and 96 percent of birds raise their young on insects. They are crucial to preserving habitats, and can support 35 times more insect-eating birds than non-natives. Ever-increasing population density in cities makes it more important to consider the impacts of the built environment on wildlife habitats. To promote avian biodiversity, urban areas must be suitable for both humans and wildlife.
Because local insects did not evolve with non-native trees and plants, many lack the ability to overcome a non-native tree’s natural defenses and must feed elsewhere. Caterpillars, a fundamental food source for breeding birds, are one of the most specialized groups — over 90 percent of butterfly and moth larvae feed exclusively on certain plants. Currently, more than 80 percent of suburban areas are landscaped with Asian flora, leaving a food-barren environment for birds looking to find nourishment. When non-native trees replace native species, entire food webs can be disturbed by loss of adapted insects, wiping out sustenance for birds.
A study conducted through Smithsonian’s Neighborhood Nestwatch program found birds are more likely to build nests in yards dominated by native trees, and will fly farther to find grub if nest locations are not ideal. Although humans may find non-natives exotic and alluring choices for their landscapes, such choices can decrease birds’ survival and fitness, as many lack nutrient-dense seeds and fruit and may lure birds toward predators. Research by ecologist Amanda Rodewald found that chickadees nesting in invasive honeysuckle reared 20 percent fewer young due to increased predation during the breeding season. Non-native trees can be destructive to bird populations by disrupting natural selection.
Help protect habitats that allow birds to flourish by landscaping your yard with native trees. Birds, insects and many other species will thank you!
Visit the MARC Water Quality native plants page for more about native trees, including some that display fall color. »