As of Monday night, the speed limit on the William B. Umstead Bridge in Manns Harbor is lowered at dusk and dawn to protect roosting purple martins.
The N.C. Department of Transportation said it is temporarily lowering speed limits from 55 mph to 20 mph at sunrise and sunset on the bridge in Dare County known locally as the Old Manns Harbor Bridge. The speed limit is monitored by law enforcement and allows motorists and birds safe passage across the sound.
From late July through August, the west end of the bridge is inhabited by about 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.
NCDOT has partnered with the Coastal Carolina Purple Martin Society since 2007 to educate the public about the flock and protect the birds and motorists. 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, according to the department.
Travelers can use the Virginia Dare Memorial Bridge to avoid the purple martins. Those wishing to view the flock safely can do so at Dare County’s multipurpose pier at the west end of the bridge.