The Bob Kerrey Pedestrian Bridge illuminates Omaha's skyline, but the bridge's lights may contribute to the deaths of migrating birds in the spring and fall.
So, federal wildlife officials have asked the city to turn off all but essential bridge lights from April 15 through May 31 and Sept. 1 through Oct. 31.
Parks Director Brook Bench said the city is looking into whether that can be done.
“We're seeing what we can do without spending a lot of money,” Bench said Friday.
Earlier in the week the U.S. Fish and Wildlife Service notified Bench of its concern that the bridge lights could be claiming the lives of night-migrating birds.
Robert Harms, a wildlife biologist with the service, said many birds migrate at night and can become disoriented by bright lights. Birds at risk include robins, warblers, herons, cranes, geese and sandpipers.
Federal law protects migrating birds from direct and indirect threats, Harms said.
Common indirect threats are things such as city lights, power lines and guy wires.
Harms said no bird carcasses have been found on the bridge that links Omaha and Council Bluffs, but that it's likely birds are falling into the Missouri River.
The agency is asking that the pylon and cable lights be turned off, while the deck lights and emergency beacons can stay on. Deck lights guide pedestrians and cyclists across the bridge, and the beacons warn away boats and planes.
Bench said the city faces two obstacles in complying:
» The lighting system wasn't designed to be turned partly off.
» Some of the lights that the Fish and Wildlife Service have asked the city to turn off also contribute to visibility for people using the bridge.
Harms said the bridge sits in the path of a major migratory path: the Missouri River Flyway, which is why bird deaths are likely occurring.
Artificial light can be deadly because birds navigate at night by visual cues such as stars, said Ben Marks of Chicago's Field Museum of natural history.
City lights confuse birds, which sometimes will circle the lights repeatedly until they collapse in exhaustion.
Chicago has led the nation with a bird safety program that emphasizes turning off skyscraper lights by 11 p.m. In Chicago, bird deaths plunged after that effort got underway.
“You'd think birds would figure it out,” Marks said, “but they're bound by nature. That's what they know.”