What Dead Birds Can Tell Us About Climate Change
Over the past 40 years, ornithologist David Willard has added some 100,000 birds to the Field Museum of Natural History's extensive bird collection. Willard has collected, measured and preserved migratory birds that perished when they hit big buildings in Chicago. The buildings birds fly into include places like McCormick Place on the lakefront and high-rises downtown.
Willard, who is now collection manager emeritus at the Field Museum, has been collecting birds since 1978; in recent years he’s been getting help from volunteers with the Chicago Bird Collision Monitors. Each year, they rescue birds that hit downtown buildings and are hurt. But on those rescue missions, the volunteers also collect several thousand migrating birds that die after they hit buildings as they fly through Chicago. The volunteers deliver the dead birds to Willard at the Field Museum.
Willard’s is a unique collection for a number of reasons, including the wide variety of species and the fact that all the birds have been measured and weighed by one man with the same tools.
That consistency is one reason scholars at the University of Michigan were intrigued that Willard’s measurements showed the bill size of the most numerous bird in the collection — the white-throated sparrow — was getting smaller. They used Willard’s painstakingly collected data in a study that looks at connections between smaller body size in birds and increases in global temperatures. Think of it as a sparrow example of the ‘’canary in a mine shaft.”
“Our findings suggest that warming‐induced body size reduction is a general response to climate change,” according to the study. The Michigan scientists intend to continue their research into the links and implications of shrinking bird size and climate warming.
We thought you’d like to get a peak at Willard’s collection.
When a bird comes in Willard weighs it, measures its wings, a leg bone and bill size. Because it’s a bit of a messy job, he writes down the information by hand in a ledger; the information is later logged into a computer.
Some birds become study skins. Their insides are stuffed with cotton and they are preserved according to species in rows of chests.
All these study skin birds get “toe tags.” The attached information includes the building they hit and the person who found them.
Other specimens are skeletonized. Some by maggots in aquariums. The results look like this.
The skeletons are transferred to boxes that again document the building where the bird perished and the person who found the bird.
Jerome McDonnell covers the environment and climate for WBEZ. You can follow him @JeromeMcDonnell.