by Wendy

Butterfly with Echinacea

A Summary of the Habitat Hero Presentation at the Denver Botanic Garden

I love learning new information about gardening and the natural world. And the presentations given at the Habitat Hero program January 23, 2016 in Denver still has me really excited. The entire morning was illuminating with excellent talks by local landscaping and birding experts Jim Tolstrup and Dave Leatherman. Then Doug Tallamy, Professor of Entomology at the University of Delaware, and stepped up and hit it out of the park with his talk "Creating Living Landscapes".

Groundbreaking research including much by Prof. Tallamy and his students, has brought to light the importance of native plants in the web of life that extends beyond the usual reasons for using native plants. It's a complex subject, but his presentation put it together in such a visually beautiful and easily understandable way, that everyone in the audience was on board. What he has discovered is that native plants are integral as food sources for plant eating insects in a way that non-native plants are not. And these plant eating insects are the foundation of the food web for song birds and all the other mammals, reptiles and amphibians that share the land with us.

Hummingbird with Honeysuckle Vine (Lonicera)

Specifically, he points out that due to the loss of natural habitats containing a diversity of native plant populations and the extensive planting of non-native trees and woody shrubs in our urban and suburban areas, song bird populations in the US have decreased by 50% and more than 230 species of North American birds are at risk of extinction! The expression "canary in a coal mine" is especially apropos in pointing out that in the web of life, when bell weather creatures like song birds are imperiled, we must take notice and do something to correct a dire situation. And fortunately, gardeners are in a position to lead the charge. Allow me to explain.

Swallowtail butterflies on Penstemon Red Riding Hood

Native trees species are especially important and productive plants used as food sources by butterflies and moths to feed their caterpillars. And 96% of terrestrial birds species rear their young on caterpillars. It takes an astounding 6-9,000 caterpillars for a mating pair of birds to feed one generation of chicks before they leave the nest. I felt fatigued just thinking about the responsibility of having to provide fresh caterpillars every three to five minutes, sun up to sun down for weeks on end. Baby birds need a lot of caterpillars. And unfortunately, many non-native trees and shrubs so commonly used in American landscapes are inedible to most all caterpillars. Combine this with the fact that there are over 40,000,000 million acres of lawn in the US, and you can see that we have created a vast area of landscapes that are devoid of ecological value to insects and all the creatures that depend on them for food.

Are non-native plants bad? No, they're not. But what Prof. Tallamy is advocating, is that we need to use them in moderation and not to the exclusion of native plants. By planting a mix of native and non-natives, we can replenish the food plant diversity so important to healthy insect populations and still have a beautiful, property enhancing landscape. We also need to change our mindset about plants and insects. Plants and the specific insects that feed on them have evolved over thousands of years to co-exist. Humans need to recognize and appreciate this intricate balance of nature and take care to be tolerant of a insects feeding on our landscape plants and not destroy these precious insect populations by careless and indiscriminate pesticide use.

Agastache Acapulco Salmon Pink Echinacea tennesensis Rocky To Hybrid Vernonia lindheimeri
A collection of native plants: Agastache Acapulco Salmon Pink, Echinacea tennesensis Rocky Top Hybrid, Vernonia lindheimeri.

We as gardeners can take an active role in healing this damage to our environment and restore our precious song bird populations. Our job is to learn about the most productive native plants in terms of butterfly and moth preferences in our region and plant them. We need to encourage our gardening friends to plant them. We need to educate our local landscapers which species to use. And insist that landscape designers and landscape architects specify these plants so to generate demand that encourages our nursery industry to diversify their wood plant palette to include them. It's a collaborative effort that involves all aspects of the nursery industry, plant sellers and end users (us gardeners).

Thank you Prof. Tallamy for bringing this to our attention and keep doing the wonderful scientific research that will continue to point us all in the right direction.

Text and Photos by Founder and Chief Horticulturist David Salman.

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