A Canada warbler found dead on a Portland sidewalk. (Doug Hitchcox photo)
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I don’t know how to be a good environmentalist. More specifically, I struggle with how to share the things I love about nature while also talking about all the ways humans are destroying it.

Focus solely on the problems – climate change, habitat loss, plastic pollution, you name it – and you’re a bore. Focus only on the pretty stuff and you’re a Pollyanna.

The struggle is most pronounced during spring migration when billions of colorful birds return from the tropics to the greening north. May is the happiest month for Maine birders. Every morning is Christmas morning, except the presents are in the trees not under them. I love spring migration with all my heart, but I can’t let this one go by without a discussion of one of the ways we’re killing these migrants: glass.

More than 3.5 billion birds migrate into the United States each spring from parts south. Double that number to include nonmigratory birds and you’ve got a pretty good estimate of the total birds in the country. The U.S. Fish and Wildlife Service estimates that between 365 million and 988 million of those birds die each year after colliding with glass windows.

Using the absolute lowest estimate, that means 1 million birds are dying every day from building collisions. Except for feral cats and habitat loss, building collisions kill more birds than any other human-induced cause of bird death, including wind turbines (an estimated 200,000 per year), poison (72 million), and oil pits (750,000).

Birds fly into glass windows because they don’t know what glass windows are. To their eyes glass is either invisible, and they collide while trying to fly to something they see on the other side, or it’s reflective, and they die thinking they’re about to land on a reflected piece of vegetation. These collisions are especially prevalent during spring and fall migrations when many more birds are on the move.

I volunteered for an organization called Lights Out DC for several years when I lived in Washington, and my job was to walk a specific city route very early on spring and fall mornings and count dead birds. I saw all kinds: woodpeckers, hummingbirds, woodcock, warblers, sparrows, tanagers, kinglets.

The buildings with the most birds piled up out front were invariably the ones with the most glass. The Thurgood Marshall Judiciary Building near Union Station has a huge glassed-in atrium filled with real trees. TechWorld Plaza on K Street has a mirrored skywalk, nearly invisible.

Thankfully, this is a problem with an easy, proven solution: help birds see windows and they don’t collide.

Tapes, frits, etchings, ultraviolet insets, and other materials break up the reflection of a window while remaining barely noticeable to the human eye. The products are available and improving all the time, but they aren’t free. Thankfully, some cities are mandating bird protections in their building codes.

The problem is not limited to cities – a bird is perhaps more likely to encounter your suburban kitchen window than an urban high-rise – but cities are taking the lead. New York City now requires new construction to include bird-safe technologies on the lower floors, where the most collisions occur.

Portland should pass its own regulation. Much of the new construction in this city features glass facades or mirrored windows, both of which are deadly to migrating birds. Studies have shown that by incorporating bird-safe technologies early in the design process, these deaths can be prevented without adding to a project’s cost.

There are a lot of problems out there for the environmentalist to worry about, but this one is fixable. So let’s fix it.

Nick Lund of Cumberland is outreach and network manager at Maine Audubon. He has written about nature for the National Audubon Society, Down East, National Parks Magazine, The Washington Post, and others. He can be found online at TheBirdist.com and on Twitter @TheBirdist.

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