How artificial lights confuse migrating birds, and how going ‘Lights Out’ can help them
Apr 30, 2024 —
This is the time of year that birds start to migrate en masse, moving from their warmer winter homes back north.
To aid their journey, and to cut down on bird deaths, New York has ordered all state buildings and offices to dim or turn off non-essential lights at night. The program is called Lights Out.
Starting in 2022, New York has required state buildings and offices to dim or turn off nonessential lights at night from April 15 through the end of June. That’s when many birds migrate, and they mostly do so at night.
Peak migration is between May 15 – June 15, when there are “thousands of birds every evening, moving through the sky,” said Dan Rosenblatt, a wildlife biologist with the Department of Environmental Conservation; he runs the wildlife diversity section out of the DEC’s office in Albany.
Roseblatt says many birds use light cues to navigate on their journey. “A whole suite of the species actually use stars to help navigate across the night sky,” he said.
Human generated light is a particular problem, he said, “when there’s cloud cover and they can’t see the sky…light on the ground seems to distract them and essentially send them off course.”
New York’s Lights Out program is about reducing the number of fatalities in migrating birds by requiring state buildings to cut down their light.
“Particularly during this time of year, it’s good policy for the environment in general as far as reducing electricity,” said Rosenblatt, “but specifically for the birds, turning off all nonessential lighting helps to reduce that [harmful] light pollution.”
He said there are a few ways that artificial light confuse migrating birds.
One is that human created light can mimic the night sky and confuse birds that navigate via the stars.
“So they can actually get disoriented and confused and essentially get wind up going off course,” explained Rosenblatt, “and wind up going to locations that they don’t mean to. They might come into a city habitat that they normally would have circumvented.”
That can lead to deaths or just send birds off course and on a longer journey.
Artificial lights can also attract birds. Rosenblatt’s seen that first hand when he worked on Long Island, at a well known lighthouse. “On particularly cloudy evenings during the spring migratory period you might get 80 to 100 dead birds at the base of the lighthouse.” What was happening was that birds that were migrating along the coastline would head towards the lighthouse in cloudy conditions, travelling at “30 or 40 miles an hour as they’re heading towards it. They don’t see the structure underneath the light. It’s kind of like night blindness and they actually just collide directly with the structure.”
Changes in human architecture have increasingly poised a problem to migrating birds as well, specifically large glass covered building that reflect the sky at night.
“Where they’re not quite sure whether they’re actually flying into a structure or they’re just flying into open space because it’s a reflection of the sky behind,” said Rosenblatt.
The official state effort to reduce lights during the migratory period, ‘Lights Out,’ is part of a much larger movement, says Rosenblatt, that includes local chapters of National Audoban, and research groups like the Cornell Lab of Ornithology.
“All these organizations that have been studying these effects, they all basically look for volunteers [to reduce artificial lighting] wherever they can.” He said that can look like “an independent businesses, folks that own a lot of real estate, or individual land owners.”
Everybody can participate, said Rosenblatt.
He said to think about how you can reduce “lights inside a house, external lights, flood lights, that sort of thing.” Folks who have control over lighting situations in a business or in a town can consider their footprint, “you know, even like the lights on a ball field, that as soon as that Little League game is over, if those if those lights could go off,” said Rosenblatt.
Light pollution across the globe has been increasing for a long time, especially in the past two decades. But Roseblatt says progress is being made. For example, lots of public lights, like streetlights, are being replaced with led lights that face downward and don’t shine up into the sky, which makes them a lot less visible to birds.
“Almost like these little polka dots on the landscape. And it’s very subtle… you’re basically, it’s almost like you’re seeing the shadow of the light instead of, you know, looking directly into a lamp. And that can make all the difference in the world for a species that might mistake that light as a cue from the sky. And suddenly get disoriented and you know not knowing which which ways up or what direction they’re going.”
Northern New York might seem like small potatoes when compared to big metropolises like New York City, and Buffalo.
But in a sea of dark, light can be even more disorienting, said Rosenblatt. He said a city like Plattsburgh, without much light pollution around it, can be dangerous on a cloudy night.
“If the birds are heading in the vicinity of the Plattsburgh area and you wind up getting one of these fronts moving through that has really low cloud cover…the birds will kind of move below the clouds. And that’s a scenario where having that that sort of singular city might actually be sort of like a stronger attraction for them,” he said.
“But the flip side of that is if a city like Plattsburgh participated in this program, theoretically that would clear the area for a much larger area for birds to be able to move through.”
The same is true for Watertown, and Saranac Lake, and Postdam.
Rosenblatt also pointed out that the vast majority of bird collisions with buildings happen within 30 feet of the ground, many of them with large picture windows that are perceived by birds as open spaces.
That means every house in rural areas has a role to play in keeping birds safe. Rosenblatt said you can break up windows and make bird collisions less likely to happen.
“If you can actually put something in the window that kind of breaks up the reflective surface…folks like using decals or streamers and things like that that are hung up in the window. So it basically just breaks up that reflection of the open space behind them.
He also warns against putting bird feeders very close to one’s home, especially the new birdfeeders that stick to windows via a suction cup.
