Migratory birds killed in collisions with glass buildings
Every year, untold numbers of birds die when they fly into glass. Campaigners in North America are trying to document the deaths, while calling for building owners and architects to help prevent them.
Migrating birds are particularly at risk. They use the stars to navigate, but appear to be confused by city lights. In unfamiliar urban surroundings, they often collide with buildings at speeds of up to 30mph (48kph).
Anne Lewis is a retired architect and founder of Lights Out DC, a group that wants Washington DC buildings to turn off unnecessary lights during the spring and autumn migrations.
Volunteers collect dead birds from the streets and then team up with biologist and photographer Sam Droege of the US Geological Survey. He photographs the often exotic birds before donating them to the Smithsonian Institution.
The portraits are then used to help sway urban developers and gain support for birds' plight.
Bird images courtesy of Sam Droege / US Geological Survey
Produced by Colm O'Molloy; edited by Bill McKenna
Altered States is a series of video features published every Wednesday on the BBC News website which examine how shifting demographics and economic conditions affect America on a local level.
20 May 2014