The human population has also adjusted: “Initially, I did receive complaints that the cross was too dimly lit, but everyone is used to it now,” Mr. Wilson said in an email.
At our best as a species, this is what we do: We change our ways to protect others, and then we adjust to the new ways. Soon, we can’t remember doing things differently. This is why lights-out initiatives are spreading across the country. Atlanta, Boston, Cleveland, Dallas, Denver, Indianapolis, Miami, Minneapolis-St. Paul, San Francisco, St. Louis and a host of other cities, large and small, are working to create safe passage for migrating birds.
Birds are in profound crisis, and these efforts can make a measurable difference in their populations: A 2021 study by Field Museum scientists analyzed 20 years of data collected at Chicago’s McCormick Place convention center. The researchers found that merely darkening the windows resulted in a roughly 60 percent reduction in bird mortality. That study points the way to other accommodations. In New York, the Sept. 11 memorial lights are now turned off for 20 minutes at a time to give disoriented birds a chance to disperse.
Homeowners can do their part, too. If you can’t turn off all your lights, identify the ones that are truly necessary and reduce the wattage or reorient them in a way that is safer for wildlife. Lights triggered by motion detectors are far less dangerous for birds than continuously burning lights, for example. The same is true for hooded lights that direct the illumination downward rather than into the sky. Indoors, draw the curtains and close the blinds after dark. Turn off lights in empty rooms. Use lamps instead of overhead lights in the room you’re in.
Migration seasons don’t last very long, so it isn’t strictly necessary to make these changes permanently, but it would be better for wildlife, and better for the climate, if we did. Vast numbers of wild creatures are nocturnal. They evolved to hunt — and to avoid being hunted — in darkness. And as the writer Paul Bogard points out in “The End of Night,” darkness is good for us, too. We evolved to rest in darkness.
I thought my husband and I had long ago made our house as bird-safe as possible. We followed the recommendations of the Cornell Lab of Ornithology, hanging screens on our windows and putting closely spaced stickers on the glass storm doors. We just didn’t make the house safe enough. Before I tucked the doomed yellow-rumped warbler under a tree, where some hungry scavenger could at least make a meal of it, I studied its curling feet, its flawless plumage. It broke my heart. The only thing wrong with that perfect little bird was our storm door, which had somehow drawn it from its nighttime path.
We’ll never be able to make this house completely safe for our wild neighbors, but that warbler was a reminder to take even more care with lights and glass, especially during the migration seasons. I have no choice but to try. It’s hard enough to feel powerless in the face of the many dangers my own species has created for the species whose ecosystems we share. It’s far worse to feel personally responsible for those dangers, too.