Native Plants + Specialized Insects = Healthy Food Web for Birds

Sharing beautiful photos of birds eating insects or feeding caterpillars to baby birds, Dr. Doug Tallamy acknowledged in his Bringing Back the Natives talk on April 26^th that most people did not share his love of insects, but many did share his love of birds, plants and healthy ecosystems. He cited numerous scientific research studies to show that if we want birds, we need the insects they eat and feed their young. And, if we want these insects upon which the birds depend, we need the native plants that these insects co-evolved with to eat. He described the specialized relationships that birds, insects and plants have developed through adaptation that resulted in a sustainable balance in the past, but which is no longer the case today. 

He used the steep decline (99% since 1976) of the monarch butterfly (Danaus plexippus) as an example. Monarch caterpillars evolved to only eat certain kinds of milkweed, such as Showy Milkweed (Asclepias speciosa) and Narrow Leaf Milkweed (Asclepias fascicularis). He described how monarch caterpillars have learned to sever the midrib of the leaf to cut off the flow of the poisonous sap that would otherwise glue its mouth shut, enabling the caterpillar to eat the leaf. While this worked for centuries, development, droughts and wildfires have destroyed the natural habitats where milkweed once grew abundantly. No milkweed. No caterpillars. No monarch butterflies.

Dr. Tallamy’s talk was actually much more inspiring than you might imagine. He fervently believes that we can still have a significant positive impact in rebuilding the diversity and stability of the local food web in our area by planting native species – especially those keystone species that provide the most bang for our buck in terms of food for insects and birds. Because most of our country’s land is privately owned (86% east of the Mississippi), our natural parks are too small and fragmented to support our insect, bird and wild animal populations. So it’s up to us to develop a “21^st Century Landscaping Aesthetic” that chooses plants not just for their beauty but for the food and habitat they provide for our local wildlife. 

One of the most important keystone species in North America is the oak, which grows readily in our area. According to Dr. Tallamy, over 270 species of moths and butterflies depend on oaks to feed and house their caterpillars. He compared this generosity of oaks to ginkgo trees, which are from China and provide food for no species of local moths and butterflies. Other keystone species for our area include: Catalina Cherry (Prunus ilicifolia ssp. lyonii), California Lilac (Ceanothus), Flowering Currants (Ribes), and many more. For a more complete list, click here. 

He encouraged viewers to imagine our trees, shrubs and perennials as big birdfeeders. Some birdfeeders (oaks, lupine, sunflowers) are full of birdseed, while others (eucalyptus, ivy, lavender) are almost empty. He said that recent research has shown that landscapes with 70% of native plants – if they are keystone species – can sustain wildlife populations at sustainable levels, leaving us 30% of our gardens to devote to nonnative ornamentals. He encouraged viewers to tolerate some insect presence or damage even in our fruit and vegetable gardens, because given time, natural predators will come and keep them in check.   

Watch Dr. Tallamy’s entire presentation along with his answers to viewers’ questions: