100 million birds die every year after colliding with buildings in America.
How many of these are in San Francisco? The city aims to find out.
The San Francisco Examiner reports that planning department officials are trying to collect data on birds colliding with buildings during the fall migration season.
The Bird Friendly Monitoring and Certification Program is asking people in residential neighborhoods to count bird corpses near their homes and apartments.
Planners are asking residents to "monitor the perimeter of their building, and especially under windows, for dead and injured birds," the newspaper reported.
In particular, planners are looking for hummingbirds. They're small, you see.
Results will be collected weekly through the end of November.