Birds versus buildings: Rural structures post greater relative threat than urban ones

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July 20, 2017







About one billion birds are killed every year when they unwittingly fly into human-made objects such as buildings with reflective windows. Such collisions are the largest unintended human cause of bird deaths worldwide — and they are a serious concern for conservationists.
A new paper published in June in the journal Biological Conservation finds that, as one might suspect, smaller buildings cause fewer bird deaths than do bigger buildings. But the research team of about 60 — including three co-authors with the University of Washington — also found that larger buildings in rural areas pose a greater threat to birds than if those same-sized buildings were located in an urban area.
Lead author of the paper is Stephen B. Hager, professor of biology at Augustana College in Rock Island, Illinois. Co-author Karen Dyson, an urban design and planning doctoral candidate in the UW College of Built Environments helped collect bird-collision data and assisted in editing the paper, along with UW alumni Anqi Chen and Carolyn Foster.
The research team monitored 300 buildings of varying size and environmental surroundings for bird mortality at 40 college and university campuses in North America in the autumn of 2014. This included six buildings on the UW’s Seattle campus. They designed a standardized monitoring protocol so that the field crews documented bird mortality uniformly. In all, they documented 324 bird carcasses of 41 species. At each site, somewhere between zero and 34 birds met their feathery demise.
“Consistent with previous studies, we found that building size had a strong positive effect on bird-window collision mortality,” Hager and team wrote in a statement about the continent-wide research. “But the strength of the effect on mortality depended on regional urbanization.”
Why is that? The researchers think it might be related to how birds select habitats during migration, and differences in bird behavior between urban and rural populations. For ...

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