Let’s not forget about trees and shrubs, when thinking about native plants and their wildlife value.
They too are attractive to many pollinators, and are also hosts to many species of insects and larvae which are an essential food for birds during the breeding season. According to Dr. Doug Tallamy, Professor & Chair of Entomology and Wildlife Ecology at the University of Delaware, 96% of all terrestrial birds rely on insects to feed their clutch; this includes - counterintuitively - even hummingbirds!
When considering planting a tree or shrub, it is important to remember that they do not all provide the same wildlife value. Many homeowners might be tempted to plant a Kousa dogwood (an exotic species from China) rather than our native Cornus florida (flowering dogwood), because it is touted as being pest resistant. Well, that it is. As a matter of fact, according to Dr. Tallamy, it is so pest resistant that it supports no insect herbivores whatsoever, whereas our native dogwood “supports 117 species of moths and butterflies alone”. To make matters worse, Kousa dogwoods produce fruit that our native birds are not equipped to eat, thus robbing them of an important food source later in the season.
Dr. Tallamy also points out that the king of trees, when it comes to wildlife value, are our native oaks which can be hosts to “532 species of caterpillars, all of them nutritious bird food”. Sure, one might think “I don’t want to plant a tree or shrub that is going to be chewed up by insects”, but when is the last time you looked at a mighty oak and even noticed that thousands of insects and larvae were feeding on it? This is because plants and wildlife have developed interdependent relationships over millennia; relationships that we have been breaking at an alarming rate.
Let me finish with one of my favorite quotes from ‘Bringing Nature Home’:
“In the past we didn’t design gardens that play a criticalecological role in the landscape, but we must do so in the future if we hope to avoid a mass extinction from which humans are not likely to recover either. As quickly as possible we need to replace unnecessary lawn with densely planted woodlots that can serve as habitat for our local biodiversity.
Homeowners can do this by planting the borders of their properties with native trees plants such as white oaks (Quercus alba), black willows (Salix nigra), red maples (Acer rubrum), green ashes (Fraxinus pennsylvanica), black walnuts (Juglans nigra), river birches (Betula nigra) and shagbark hickories (Carya ovata), under-planted with woodies like serviceberry (Amelanchier canadensis), arrowwood (Viburnum dentatum), hazelnut (Corylus americanus), blueberries (Vaccinium spp).
Our studies have shown that even modest increases in the native plant cover on suburban properties significantly increases the number and species of breeding birds, including birds of conservation concern. As gardeners and stewards of our land, we have never been so empowered to help save biodiversity from extinction, and the need to do so has never been so great. All we need to do is plant native plants!”-- Dr. Douglas Tallamy