In this issue: interdependent ecosystems, caterpillars, new learn pages
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Joining together to break new ground for birds

July 2015

Chest-nut warbler and caterpillar
Chestnut-sided Warbler eating a camouflaged caterpillar. 
By Josh Jones, via Birdshare

Plants, Insects, & Birds

Pause to imagine the sounds of summer. For many, there are few things as lovely as sitting outside in the warm sunshine listening to the rustle of the wind as it moves through your landscape, the hum of grasshoppers rubbing their legs together, or the chatter of a flock of young birds exploring their new world. Summer is here and our yards should be teeming with life. How much life depends, in part, on the types of plants you have in your landscape.


In the United States there are 75 to 100 million acres of exotic plants in managed landscapes.1 This area is almost equivalent to the size of Wisconsin. Non-native plants, introduced from all over the world, can create modified ecosystems that research suggests do not support the same level of biodiversity as native-plant ecosystems. A study in a Philadelphia suburban neighborhood compared sites landscaped with exotic plants to those with native plants. They found that exotic-plant yards had reduced bird abundance and fewer lepidopterans (moths and butterflies).1


Why might this be? The simple answer is that many components of ecosystems are interdependent. A plant originally from Japan may not provide the correct chemical signals to announce to a butterfly native to North America that it is a suitable place to lay its eggs. Missed breeding opportunities send a ripple through the food web to native birds, a large percentage of which feed their nestlings caterpillars during breeding season. Less habitat for butterflies to lay their eggs means fewer caterpillars, and less food to feed nestlings.


Homeowners and communities can improve their local environments by:

  1. selecting native plants. From private gardens to city parks and medians, every patch of native landscape is important;

  2. creating demand at local nurseries and stores for native plants. Ask what plants are native. Ask if they can order native plants. Only 13% of all nursery sales are native plants.1 Lack of access to native plants may be driving the use of non-native plants;

  3. educating neighbors, nurseries, community landscapers, and urban planners on the intricacies of ecosystems. Encourage them to consider planting natives instead of exotic or non-native plants;

  4. engaging in citizen science. The data citizen scientists provide will help us understand more about the relationship between native plants and biodiversity. Without the science, we cannot appropriately shift practices or policy.

1 Wilde, H. D., Gandhi, K. J., & Colson, G. (2015). State of the science and challenges of breeding landscape plants with ecological function. Horticulture Research, 2.
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The YardMap team is busy creating new Learn Pages devoted to providing you detailed, informative articles on how to create habitat in your backyard. Thanks to feedback from YardMappers, we were able to determine the important categories of interest to readers. We aim to make searching for, and learning new content easier in our redesign. If you are interested in exploring these pages before we formally launch them, please email us at  We'll give you special access and invite you to provide feedback. 


  • Ask your question in our tech support community, powered by Get Satisfaction.
  • Ask fellow participants your bird and plant questions in The Neighborhood, our social network for habitat stewards.
  • Email us.

What Do Birds and Butterflies Have in Common?

Caterpillars on their native host plants. Photos via Flickr,
Creative Commons.

Caterpillars! Many birds sustain themselves, and their offspring, on caterpillars. Butterflies, which can eat nectar from several sources, often only lay their eggs on very specific species of “host plants” that they have evolved with. You may already be familiar with the Monarch butterfly and its dependence on milkweed (Asclepias spp). Here are five more native examples:

  • Pipevine Swallowtail, Battus philenor. It gets its name from the Dutchman’s pipe (Aristolochia macrophylla), a vine native to the eastern U.S.

  • Zebra Swallowtail, Eurytides marcellus. The caterpillars feed only on pawpaw (Asimina triloba), a small shrub or tree, native to the eastern half of the U.S.

  • Spicebush Swallowtail, Papilio troilus. Spicebush (Lindera benzoin), is the preferred native shrub for these swallowtail caterpillars. You may also find them on sassafras.

  • Baltimore Checkerspot, Euphydryas phaeton. If you want to see these beauties plant pink or white turtlehead (Chelone glabra).

  • Fritillaries. There are a variety of fritillaries and each variety prefers a different species of violet (viola spp).


Want to learn more about which native berry-producing plants support which caterpillars and birds? Check out this article .


Monarch on milkweed

Monarch butterfly on milkweed 
Photo by Henry T. McLin via Flickr, Creative Commons

What's Been Your Favorite Summer Sighting in Your Yard?

Monarchs on milkweed
Nesting birds
Native caterpillars and butterflies
Wildlife in your gardens
Native plants thriving


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The Cornell Lab of Ornithology is a membership institution dedicated to interpreting and conserving the earth’s biological diversity through research, education, and citizen science focused on birds. Visit the Cornell Lab’s website at

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