I’ve written a number of articles on how native plants usher in wildlife. I read an interesting article, “Grow Native Plants” in The Cornell Lab of Ornithology’s Spring 2014 Living Bird Magazine, which gives a simple recipe for attracting warblers, the well-loved but evasive group of songbirds. Plant native plants. For warblers and other songbirds, caterpillars (lepidoptera larvae) are the most important food source for warblers, especially at nesting time. “The number of caterpillars each pair requires is mind-boggling,” the article states. For example, video recordings of 18 different Black-throated blue warbler pairs showed an average 22 trips per pair, with caterpillars comprising 60-87 percent of the food delivered.
Non-natives deprive birds and other wildlife of food
When you choose non-native plants remember that they have caterpillars back in their homelands in Europe or Asia. But our native caterpillars don’t eat them because they haven’t evolved to adjust to the chemical defenses produced by the plant. Some prefer non-native plants because they are touted as having fewer pests, which negatively impact birdlife. Two researchers studying the caterpillar production of natives versus introduced plants said the following:
“Every time we plant an introduced plant, we are reducing the local insect population and thus depriving birds and other wildlife of the food they need to survive and reproduce. – D. Tallamy and K. J Shroshire, Conservation Biology, 2009
I’ve observed this in our our yard’s native plants. Especially our native ceanothus (wild lilac) and manzanitas attract so many insects, which in turn attract birds. Yes, their blooms attract the imported European honeybee, which is important, but they especially attract numerous sizes of native bees and wasps.
At the same time, songbirds carry an economic value as they keep infestations of problematic caterpillars such as tent caterpillars. Interestingly, we’ve noticed many fewer orb spiders, which we love to watch at this time of year. One likely reason is the pair of Bewick’s wrens that raised a brood, and were constantly perusing our yard this spring for spiders and other insects.
Another reason to go native!