Fatal chirps: nocturnal flight calls increase building collisions among migrating birds
White-throated sparrows that were part of a large U-M-led study of nighttime building collisions in the Midwest. These birds died after colliding with buildings in Chicago. Image: Roger Hart/University of Michigan Photography
Birds that produce faint chirps called flight calls during nighttime migration collide with illuminated buildings much more often than closely related species that don’t produce such calls, according to a new analysis of a 40-year record of thousands of building collisions in the Midwest.
The new analysis of more than 70,000 nighttime songbird collisions in Chicago and Cleveland suggests that birds disoriented by artificial light from illuminated buildings at night send out flight calls that may lure other nearby birds to their death.
The study, published online April 3, 2019, in Proceedings of the Royal Society B, is one of the first comparative studies of avian social behavior during nocturnal migration.
“Nocturnal flight calls likely evolved to facilitate collective decision-making among birds during navigation, but this same social behavior may now exacerbate vulnerability to a widespread anthropogenic disturbance: artificial light from buildings,” said University of Michigan evolutionary biologist Benjamin Winger, first author of the study.
The study relies on bird-collision data collected in Chicago by Field Museum researchers starting in 1978 and, more recently, by volunteer groups in Chicago and Cleveland.
“Our paper provides some of the strongest published evidence on the effect of artificial light on bird collisions in urban areas, though this relationship has been known anecdotally for a long time,” said Winger, an assistant professor in the U-M Department of Ecology and Evolutionary Biology and an assistant curator at the Museum of Zoology.
The other authors of the study, in addition to Winger, are David Willard, a retired Field Museum ornithologist who led the data collection in Chicago; Andrew Farnsworth, Cornell Laboratory of Ornithology; Brian Weeks, a postdoctoral researcher in the U-M Department of Ecology and Evolutionary Biology; Andrew Jones of the Cleveland Museum of Natural History; and Mary Hennen of the Field Museum.
The story was widely covered in the media including by The Chicago Tribune, PBS' NOVA and in Science magazine.
