To protect purple martins preparing for their annual migration, the N.C. Department of Transportation has lowered the speed limit and activated flashing lights at dusk and dawn on the William B. Umstead Bridge between the north end of Roanoke Island and Manns Harbor.
Each summer, NCDOT lowers the speed limit on the Umstead Bridge at dusk and dawn from 55 mph to 20 mph. The Umstead Bridge in Dare County is locally known as the Old Manns Harbor Bridge.
From mid-July through August, the west end of the bridge over Croatan Sound becomes home to more than 100,000 purple martins as they prepare for their annual migration to Brazil. The birds roost under the bridge at night, departing at dawn to feed and returning at sunset. The flock is so large during its peak that it can be seen on radar.
Since 2007, NCDOT has partnered with the Coastal Carolina Purple Martin Society to educate the public about the flock and protect the birds and motorists. NCDOT activates flashing lights and a 20-mile-per-hour speed limit on the bridge at sunrise and sunset.
The speed limit is monitored by law enforcement and allows motorists and birds safe passage across the sound. Since the lights and speed limits were installed, the Coastal Carolina Purple Martin Society has seen a dramatic decline in bird deaths around the bridge.
Those wishing to view the flock safely can do so at Dare County’s multi-purpose pier at the west end of the bridge.