The city has begun turning off lights at the Duke Energy Center for the Performing Arts and the nearby convention center late at night, mostly for the benefit of some out-of-town visitors.

For many songbirds that migrate through North Carolina each fall and spring, the bright city lights can be deadly. Lights that illuminate the exteriors of buildings as well as those left on inside can confuse birds, coaxing them to crash into windows or fly in circles until they drop from exhaustion.

The National Audubon Society and other bird groups across North America are trying to reduce the death toll by working with building owners to turn off lights when they’re not needed.

In Raleigh, the effort began in the fall of 2013 when volunteers with the Wake Audubon Society began walking downtown streets first thing in the morning during migration seasons, counting dead and injured birds on the sidewalks. Of the 27 species they found, 21 were migrants, such as the common yellowthroat, ovenbird, wood thrush and chimney swifts, said Rick LaRose, the group’s president.

After two years, the volunteers determined which buildings posed the most trouble for birds. Topping the list was the Duke Energy Center, which accounted for nearly a third of the more than 100 dead birds the volunteers found, LaRose said. The walls of glass on the building’s façade, lit from inside at night, as well as decorative exterior lights proved lethal to songbirds.

“It was clearly the most problematic building,” LaRose said.

Presented with Audubon’s findings, the city has agreed to turn off non-essential lighting at Duke Energy by 2 a.m., said Megan Anderson, who manages the city’s Office of Sustainability. Lights needed for security or safety, in stairwells and at exits, as well as along walking paths outside, will stay on, Anderson said.

“Anything that can be turned off will be turned off whenever everyone has vacated the facility,” she said.

A bird can become confused and fly into a window almost anywhere and at any time. But the problem is especially serious during migration seasons, when large numbers of birds are on the move at night, navigating by the stars, and in cities with thickets of well-lit buildings. In Chicago and Toronto, well-organized groups of volunteers patrol the streets below the glass towers collecting the bodies of collision victims. They work with local governments and property owners to make buildings less alluring to birds.

Those two cities also happen to be in the paths of busy flyways, resulting in as many bird casualties in a single night as a North Carolina city will see in an entire migration season, said Kim Brand, the bird-friendly communities coordinator for Audubon North Carolina. In Toronto, the Fatal Light Awareness Program, or FLAP, estimates that more than 1 million birds die in collisions with buildings there each year.

Brand oversees Audubon’s Lights Out North Carolina program, an effort that began in Winston-Salem in 2012 and has since spread to Charlotte and Raleigh. She says the disorienting effect of lights on birds was observed as far back as the 19th century with lighthouses but is still a relatively recent concern in many cities. Lights Out North Carolina got started only after a transplant from New York City brought the problem to Audubon’s attention, Brand said.

In an ideal world for songbirds, there wouldn’t be any confusing lights at night. But Audubon and other bird groups know that human needs come first when it comes to getting building owners to agree to turn out their lights.

“In Winston-Salem, when we started out by talking with individual building managers, we said, ‘Can you turn your lights off at 9?’ and they kind of laughed at us,” Brand said. “So we came back and said 11 p.m., and they said ‘OK.’ ”

Wake Audubon felt it had a willing building owner in Raleigh, which already had established policies on light pollution and unnecessary lighting, LaRose said. Both he and Anderson said the city hopes to set a good example for others.

“We felt that it was pragmatic to first start with the city-owned buildings,” LaRose said. “Our hope is with the city taking the first step that will encourage the mangers of private buildings to take similar steps.”

Anderson said the city has encouraged its workers and custodial crews to turn out lights in office buildings when they’re done for the evening – steps designed to save energy that also may benefit birds. She said while the city will turn out non-essential lights in the convention center after the building is emptied for the night, the Cree Shimmer Wall will remain on, because Audubon didn’t find evidence that those lights confused the birds.

“That is a big iconic part of downtown, and that will stay lit,” Anderson said.

Wake Audubon volunteers will hit the streets again next fall to see how well the dimming efforts are working, LaRose said. In Winston-Salem, Audubon members said the Lights Out program cut the number of bird-building collisions in downtown by about 30 percent, Brand said, even with the limited hours.

“We can still save hundreds of birds lives in North Carolina and make a difference,” she said.