The new PNAS study is the most in-depth use of the data on lighting patterns to date, combining Willard's specimens and lighting observations with other conditions that might play a role in bird mortality, including weather records and radar data revealing the number of birds in the sky on a given night. As the building's lighting patterns began to vary more, he began gathering data on which windows were illuminated each night, in addition to collecting the birds he found on the pavement. Willard collects the dead birds and brings them back to the museum, where he records each one in a ledger and adds them to the museum's collection.Īround twenty years ago, Willard began to notice a pattern - on nights when the lights were out at McCormick Place, around holidays or construction work, there were fewer birds on the ground the next morning. Some days there are no birds other times, there are as many as 200.

Willard and his colleagues, including Field Museum co-author Mary Hennen and other Field staff and volunteers, have visited the site every day before sunrise during migration season, sometimes as early as 3:30 in the morning. 'I might not have gone back if I hadn't found anything that first day, and now here we are, 40 years later and 40,000 birds later.' 'I went down early one morning, just out of curiosity, and wandered around and actually found four or five dead birds,' says Willard. In 1978, Willard, the museum's collections manager emeritus, heard an offhand remark about birds hitting the McCormick Place, North America's largest convention center that happens to be just a mile south of the museum.

'These insights were only possible thanks to over 40 years of work by David Willard at the Field Museum, who led collisions and light monitoring efforts.' 'Our research provides the best evidence yet that migrating birds are attracted to building lights, often causing them to collide with windows and die,' says Benjamin Van Doren, a postdoctoral associate at the Cornell Lab of Ornithology and the paper's lead author.

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