Patty Loew:
We begin this week with an annual rite of passage. Millions of migratory songbirds fly over Wisconsin on their way to their summer breeding grounds and then back again in the fall. Every time they face a deadly obstacle. So common that we may never notice. Scientists estimate that every year in North America up to a billion birds, that's a billion with a B, are killed by flying into windows. "In Wisconsin's" Jo Garrett shows you why this is a big problem in Milwaukee.

Jo Garrett:
It's a day in May, a bleak and blustery day in downtown Milwaukee.

Man:
Wind hazard.

Jo Garrett:
It is early morning and Scott Diehl is on a search and rescue mission.

Scott Diehl:
But now...

Jo Garrett:
Search and rescue for small survivors like these. Diehl is the director of wildlife rehabilitation for the Wisconsin Humane Society in Milwaukee.

Scott Diehl:
A lot of glass. I think the bird collision issue has been one that has not had much awareness to date and when these buildings were built there wasn't an awareness about the magnitude of this problem. Reasonable estimates place the mortality between 100 million and a billion native birds dying in North America each year in window collisions.

Jo Garrett:
They hit the glass and they die. It's a phenomenon called window strikes. Hundreds of millions of songbirds perish every year in North America.

Scott Diehl:
This bird that weighs ten grams has flown from Costa Rica or Panama to Wisconsin across so many hazards. And they are at once amazing in their capability of flying those distances and traversing the mountain ranges and rivers and oceans and yet a 16th of an inch-thick piece of glass is enough to stop them permanently.

Jo Garrett:
The problem is particularly acute in Milwaukee, which is dead center in the Lake Michigan Flyway. The bird migration highway and oh so different from the rainforests back home.

Scott Diehl:
What happens down in this urban canyon down here, downtown Milwaukee, is there is so much confusion. There is so much glass and so many reflective surfaces that the birds really get confused. They land in this area and then it's literally a gauntlet of glass and steel and concrete that they just are not prepared to deal with.

Jo Garrett:
And all these reflections and light in this gauntlet of glass can cause collisions.

Scott Diehl:
They hit the building for one of two reasons. Either they see the lights at night when they're migrating and get confused by the light. The other reason they collide is daytime collisions, where it’s just reflections of the landscape on the glass in the daytime.

Jo Garrett:
Or the song birds see through the windows to greenery beyond and think they've found a passageway.

Scott Diehl:
They have no concept of glass. If you think about the jungle or the forest where these birds live, it is much like flying through the trees where there are gaps and so on and wending their way through the foliage and so they see in one window and out another they think they can pass through there. With deadly consequences.

Jo Garrett:
So every morning during migration season Diehl and a team of volunteers fan out across the city. It is search and rescue. Below big buildings with many windows. It is search and rescue to count the dead and save the injured. To get to that moment every rehabilitator longs for, release. Rehabilitator Elizabeth.

Elizabeth:
These are one of my favorite birds. This is a cedar waxwing. If you look on their feather tips they have the beautiful yellow and the red. It almost looks like nail polish. It's just -- I don't know, I think they're so beautiful and they make kind of a zinging noise and they -- yeah. And these were growing up when my father and I would bird a lot. These were one of my favorite birds to see. I love the waxwings.     

Jo Garrett:
WINGS is the name of Diehl's rescue group: Wisconsin Night Guardians for Songbirds.

Scott Diehl:
We have a little bird up ahead here. I'll go up and see if I can snag the little guy.

Jo Garrett:
Just outside one of the city's biggest skyscrapers Diehl finds his first casualty. A bright yellow warbler lying still against the gray cement.

Scott Diehl:
It's a Canada warbler. Poor little guy, or girl, as the case may be.

Jo Garrett:
Research has shown that one out of every two window strikes leads to a fatality. Often birds that may appear merely stunned have internal injuries that lead to their demise.

Scott Diehl:
We've got a Nashville warbler that was found dead down at US Bank between Cass and Van Buren. Look at this indigo bunting. Wintered in Panama, Costa Rica, Belize, Ecuador, whatever. Made this arduous journey back and it ends on a window in Milwaukee, I think it’s terribly sad. This is 3rd and National, which is an unusual location for us, but it illustrates it's not just downtown and it is not just tall buildings. It is any place there is glass. This is the dead ones that came in from about three weeks of monitoring. Staggering, staggering. We're talking about dump trucks full of these beautiful birds just dying senselessly and again most of us aren't even aware of the issue.

Jo Garrett:
It's an enormous problem in bird conservation. And easily overlooked.

Scott Diehl:
These are small birds for the most part. They're easily missed. People step over them on the street. Others fall into landscape shrubbery where they're never seen and others are scavenged by gulls and crows, and endangered ones are picked up by predators. If something the size of a deer was laying dead outside these businesses each morning, or 10 or 20 of them, you can really believe it would get someone to take notice.

Woman:
I hear you. There you are.

Jo Garrett:
Most are in the dark about this problem. The Wisconsin Humane Society is on a mission to change that.

Scott Diehl:
It's great to be able to treat that bird and hopefully rehabilitate it. Get it out and released. But how much better is it to prevent this in the first place? To stop this needless death and suffering for birds.         

Patty Loew:
Prevention may be the key. So, how can window collisions be avoided? Some cities are taking aggressive measures with a lights-out at night policy like here in Toronto. Homeowners can also do their part to help Wisconsin song birds during migration season. "In Wisconsin's" Jo Garrett continues to investigate the phenomenon known as window strikes next Thursday at 7:00 right here on Wisconsin Public Television.