by Kay Charter
Early last month, I had the great pleasure of hearing Douglas Tallamy speak. Doug is the author of every conservationist’s must-have book, Bringing Nature Home (Timber Press, 2007). I heard him twice, actually, as he presented two programs at the Michigan Association of Wildflowers Conference in Lansing. These presentations represented numbers seven and eight of the times I have heard him speak. Had I heard it all before? Not by a very long shot.
Doug Tallamy is professor and chairman of the Department of Entomology and Wildlife Ecology at the University of Delaware. He is also an avid birder and able photographer. His first program at the conference, “Networks for Life; Your Role In Stitching Together a Natural World,” examined the crucial role of wildlife corridors. In an effort to persuade all of us to become involved in this effort, he says, “Biodiversity is essential to sustaining human societies because it is other living things that run our ecosystems. Yet, throughout the U. S., we have fragmented the habitats that support biodiversity by the way we have landscaped our cities, suburbs, and farmland. This is a problem because isolated habitats cannot support populations large enough to survive normal environmental stresses. We can reconnect viable habitats by expanding existing greenways, building riparian corridors, and by changing the landscaping paradigm that dominates our yards and corporate landscapes. Replacing half the area that is now in barren lawn with plants that are the best at supporting food webs would create over 20 million acres of connectivity and go a long way toward sustaining biodiversity in the future.”
How do we convert our landscapes? By replacing non-native plants with native ones. Only native plants support the insect abundance upon which birds, frogs, butterflies (and all the rest of us, for that matter) depend.
Although Doug is an entomologist, even he didn’t connect the dots between the importance of native plants and insect abundance until after he and his wife purchased 10 acres in southeastern Pennsylvania. The land was filled with alien plants like autumn olive, multiflora rose, and Bradford pear. The vegetation was so dense, he and his wife had to cut trails to get into it. On a later walk through his property, he searched for insects. He found none, except on the few natives struggling to survive under the stranglehold of invasive plants. It was a defining moment for him, the ultimate result of which was his book.
Birders who still support the idea that autumn olive is good for birds will gain insight from the following: “The foliage of autumn olive is inedible for almost all native insect herbivores. A field rich in goldenrod, Joe-Pye weed, boneset, milkweed, black-eyed Susan, and dozens of other productive perennials supplies copious amounts of insect biomass for birds to rear their young. After it has been invaded by autumn or Russian olive, that same field is virtually sterile.”I had breakfast with Doug before his first presentation at the conference and he shared a sweet, but powerful personal experience that reinforced his message. “My chickadees told me,” he said.He discovered a pair of nesting Carolina Chickadees in his yard last year, and kept track of the food the parents brought their young. The pair only raised a single fledgling, but that one tiny bird required 4800 caterpillars to reach fledging. The baby bird was fed 17 different species of caterpillars, most from black cherry and oak trees.
Doug and his wife planted the black cherries and oaks on their land, so the trees are still young. Even so, they provided enough food to raise the young bird. The parents had searched for food from 6AM until 8AM every day, and they brought an average of 27 caterpillars to the nest every thirty minutes. If the Tallamys hadn’t planted the trees, forcing the parent birds to travel farther in search of food, they may not have been able to raise any young.
The important message from Doug’s chickadee pair was that if we want a healthy bird population, we must plant – or protect – native trees, shrubs, flowers and grasses in our personal landscapes.
Kay Charter is executive director of Saving Birds Thru Habitat, an organization that teaches people how to help migrating birds whose populations are declining.