When my parents first moved into their previous house, they discovered that the windbreak the former owners had built onto their patio was very hazardous for birds - it was nothing more than a sheet of heavy, double-paned window glass (probably intended to be used in a sliding glass door) with a wooden frame to hold it into place, set right along the corner of the building. It was responsible for about 1-3 avian deaths a week, since they would come flying around the corner of the house, and smack right into the windbreak. One of the first projects they gave me when working on the house was to remove the windbreak.

But before I did that, I saw on several occasions the imprint of wings on the damn thing, sometimes with a bird underneath, sometimes not. I still don't understand how even if the previous owners didn't give a crap about the birds, they wouldn't have gotten tired of cleaning up carcasses off their walkway.

The birds that whacked into my window would disappear from the ground after an hour or two. Always wondered if they woke up, or if cats got them. No foxes in my neighborhood.

A lot of times, they're just stunned, and recover to fly away, probably with a migrane. I was able to hold a goldfinch that way, for about a half an hour, until it came to and fluttered. I brought it to a protected area, where it still needed another 20 minutes before it took off. I still have the pictures somewhere, taken with an 35 mm camera.