07/26/2013 06:24 EDT | Updated 09/25/2013 05:12 EDT


OAKLAND, Calif. - Birds and buildings can be a fatal combination. The American Bird Conservancy cites studies estimating that hundreds of millions of birds die each year as a result of colliding with walls and windows.

But a movement to make skies a little friendlier is taking flight; some cities and other governments across the country are adopting bird-safety building guidelines on a mandatory or voluntary basis.