It walks along the branch of a Slippery Elm tree, looking for something to eat. This migrating Chestnut-sided Warbler is on its way to the Gulf Coast. From there, it must fly 600 miles nonstop across open ocean. At the end of its journey, it will spend the winter as far south as Panama or Colombia.
Food for the journey
Food that the bird finds on its journey has to provide all the energy for 3000 wing-powered miles. The warbler eats mostly insects, including lots of caterpillars.
Caterpillars grow on trees. But only on trees that are native to one’s local area.
Here’s the migrating Chestnut-sided Warbler finding food, on a September morning in Iowa.
A. Warbler spots the caterpillar.
B. Reaches for it.
C. Yum.
The ragged leaf
There was a time when I thought there was something wrong with caterpillar holes in leaves. But not anymore. Now, those ragged leaves tell me that insects have been feeding there and providing food for a hungry bird.
Now I get it. Warblers and many other migrants rely utterly on insects, most of which eat leaves. Not just any leaves, though. North American birds need leaves of native plants — the ones that have been growing here for thousands of years. Over the ages, our local insects have become adapted to our native plants and cannot eat anything else.
Of course, we humans like to import plants from other continents. However, our local insects find those alien plants inedible, and so alien plants simply don’t grow any bird food. A tree from somewhere else may be gorgeous, but as far as a hungry bird is concerned, it might as well be made of cement.
For birds to survive and thrive, we need native plants. Like the Slippery Elm tree where the Chestnut-sided Warbler found breakfast. When we discover that a caterpillar has nibbled on some leaves, that’s great news for us, if we want to see birds like the Chestnut-sided Warbler in our yard.
Helping birds, with native plants
For more about gardening and landscaping with native plants, I recommend the book that opened my eyes and changed the way I think. The author is University of Delaware biology professor Doug Tallamy. His Bringing Nature Home is full of insights about how native plants are the best bird feeders.
Till next May…
Safe travels, Chestnut-sided Warbler and all the other birds who migrate through my backyard. See you next May, when you stop by on your way north. There will be caterpillars emerging on new spring leaves for you.
Yes, Plant more native plants of all kinds! But to encourage birds in your yard... especially the trees, whose leaves feed many insects including the thousands of moth species, that as caterpillars feed those many birds while here to grow each batch of fledglings, but also that feed those migrating birds as they head south for the winter.
Caterpillars are made up of proteins and fat, which provide the nutrients for growth and the long lasting energy needed for those long flights. FYI - Doug Tallamy has written other books about insects and plants as well as having several video presentations available online to watch. In his books, he has great information, charts of plants to grow for each region, and fabulous photos that he shares in print and in the videos.
Thanks for the book recommendation.