Engineering bird-friendly glass

Every year hundreds of millions of birds die from accidentally flying into glass buildings and windows. But now, new types of glass may make this easily preventable. Daniel Klem, Professor of Ornithology and Conservation Biology at Muhlenberg College in Pennsylvania joins Hari Sreenivasan to discuss creating bird-friendly glass.


Every year, hundreds of millions of birds die from accidentally flying into glass buildings and windows.

But now, new types of glass may make this easily preventable.

Daniel Klem, Professor of Ornithology and Conservation Biology at Muhlenberg College in Pennsylvania, has helped to create bird-friendly glass.

He joins me now.

Hundreds of millions of birds -- Is that possible?

Oh, yes.

In fact, one might argue that this is one of the most underappreciated source of bird mortality worldwide.

And that's more than we're talking about oil spills, and all --

Exactly, exactly.


In the 1990s, my very first -- one of my first research papers that I wrote about this had 100 million birds as the lowest estimate.

And you need 333 every year to equal how many birds die on one year in the United States of windows.

But nobody's talking about windows, and we should.

You see, every once in a while, people put up a giant 'X' or put up a little silver foil.

Does that work?

It does.

You know, one of the first things I did was -- Somebody used to sell a decal, a hawk silhouette.

This comes from research in Europe about birds being innately scared of predators.

But putting that decal in the window wasn't really helpful at all.

But you need to put enough decals such that they're separated -- and this is very critical.

What my studies have revealed, for example, that you have to have -- If you're gonna orient these elements, whether it's the hawk silhouette or diamonds or circles, they have to be four inches apart in vertical columns, or two inches apart in horizontal rows.

Now, like with the glass issue and the birds behaving as if it's invisible to them, they're not talking to us why this works.

But my general interpretation is that birds give a little bit more room to fly around tree trunks than they do branches.

So, otherwise they would basically try to slide through?




So, you need to cover the window completely.

You need to have these pattern elements, uniformly separated by these distances, to completely eliminate the collisions.

Then they recognize the window as a barrier to be avoided.

But then, it doesn't necessarily feel like a window anymore if you've got stickers all over it.




And that's why, for many, many years -- really decades, because I started studying this in the early 1970s.

And the issue is that people would tell me -- even the most ardent conservationists -- 'You go mucking around with the way I look out my window, you're gonna lose.'

So it's been a struggle.

It's been now almost four decades that I've been working on this, and we're only now beginning to see glass manufacturers -- and even then, very few of them placing what's often referred to as 'visual noise' on the window to alert the birds to the danger.

So how do you design a glass that gets around that, that's still see-through and...?


Well, there's a couple of ways in which these patterns are applied.

One of them is called 'ceramic frit.'

They bond with high-temperature ceramic to the glass surface.

The other one is acid etching.

Both of them give our human eye the same kind of visual impression -- and that is like a frosted area -- that we instituted at our institution when we got around to remodeling.

What it is is a series of dots.

They're about 1/4 inch apart and spaced by about 1/4 inch.

And when you stand right next to it, it looks formidable.

You can hardly see through.

But you step back a couple of feet, you can look through it.

So, if you're willing, right, to put up with this sort of modest amount of visual noise, then you'll be successful.

There's an architectural firm in Chicago that's just recently completed a building where they placed this kind of frit on the first four stories.

And how's it working?

Oh, it works well.

I mean, again, it really does solve the problem.

Again, it transforms that space that's occupied by the window into a barrier that birds will see and avoid.

Now, in this very same corridor in our campus, right -- We have had this up now for at least four or five years, not one window strike.

But the conventional windows around the rest of the building -- About a dozen birds a year die.

The elegant solution is sort of the cutting-edge area.

That's the area where we use ultraviolet signals, where we humans don't see them, but birds do.

So, picture being able to look out your window.

And so, those conservationists that had that problem, it's gonna go away.

But the problem has been -- for me, anyway -- is that although I have had some industry cooperators to produce some prototypes for me that I've been able to demonstrate worked, they're not willing to commit the investment, because they don't know whether they're going to get their return.

If I can use their language, the hole in their business plan is how many bunny-huggers or tree-huggers are going to buy the glass.

But that's not the issue.

I've tried to convince them that the world needs retrofitting.

The world needs attention to this issue.

And, as far as I'm concerned, the world is... Our national parks -- You can't go to a visitors center in a local or state or national park without seeing it lavishly covered with glass.

And, sadly, sort of the dirty little secret is that it's also killing the birds that people come to see.

Daniel Klem of Muhlenberg College, thanks so much.

Oh, you're very welcome.

Thank you.