‘No one wants a building that kills birds’: why cities are turning off the lights

As avian numbers plunge, activists demand action to save birds from crashing into high-rise blocks

The wren's legs were tucked delicately underneath its diminutive body, slumped on its side as if asleep. If it wasn't lying on the bare concrete of a Texas street, there would be few clues that it had endured a crunching, violent death.

The bird had flown headfirst into the Bank of America building, a 72-storey modernist skyscraper in the heart of Dallas. Its corpse was catalogued by volunteers who seek to document the toll of birds that strike the glass, metal and concrete structures festooned with bewildering lights that form the skylines of our cities.