Seasonal Cycles: Migratory Birds

Many people are enthusiastic about the return of familiar birds in the spring from their southern wintering grounds. Concord has the longest records of bird arrival dates in North America. This record begins with observations made by Thoreau, and has been continued until the present by a number of Concord residents over the past century and a half. These records have been analyzed to determine whether climate change is affecting bird migration timing the way it is with plant flowering times and insect emergence.

As a group, bird species tend to be less responsive to the effects of climate change than local plants and insects. Some bird species are responding to climate change by arriving in Concord earlier in warmer years than colder ones, but others have not changed their arrival dates, and a few species are even arriving later. Other species that used to migrate now spend all year in Concord, a change made possible in part by people putting out bird feeders. Because migratory birds as a group are responding to climate change at a different rate than plants and insects, there is the possibility that birds returning to Massachusetts may miss the peak abundance of their insect food source.

Spyglass, England, about 1853

Buying this spyglass in 1854 revolutionized Thoreau’s bird watching, bringing the living bird closer. Normal scientific practice at the time was to shoot the bird and then make a positive identification.

Wilson's American Ornithology.

Alexander Wilson is often called “the father of American ornithology” because of this guidebook, Wilson’s American Ornithology, first published in 1814.

The Christmas Bird Count

The Christmas Bird Count (CBC), the longest running citizen science survey in the world, provides critical data on bird population trends. The first Concord CBC census was in 1960.

To Learn More

Read about the “Effects of Climate Change on Spring Arrival Times of Birds in Thoreau’s Concord from 1851 to 2007,” in The Condor, 2010.

Learn about the Concord Christmas Bird Count.

Explore the work of Concordian David Sibley, America’s leading ornithologist/illustrator.

Background photo credit: Larry Warfield
Photo credits: David Bohl; Cherrie Corey