Purple Martin Bridge Roost
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Welcome to Manns Harbor
Purple Martin Bridge Roost
The Outer Banks of North Carolina are famous for beautiful beaches and other natural attractions, including a fascinating roost of purple martins here at William B. Umstead Memorial Bridge. East of the Rocky Mountains, martins are completely dependent on people to provide them with nesting structures in which to raise their young. Without their caring “landlords,” these birds would likely become very rare throughout the eastern United States.
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Purple Martin Facts
• Purple martins are social colony nesters and prefer the company of other martins.
• The largest known colony of martins consists of over 700 breeding pairs of birds and their young!
• Martins enjoy a close relationship with people and typically nest within the safe zone of a human dwelling where there are fewer predators.
• Adult males do not attain their characteristic purple plumage until 2 years of age; females and young are grayish.
• Purple martins are our largest swallow species measuring 7-8” from beak to tail.
• Purple martins are beneficial birds eating only aerial insects caught in flight.
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Home to 100,000 Purple Martins
Purple Martin Madness
You won’t believe it when you see the martins in action! 100,000 martins converge on this bridge every night from July through August (although the roost is active from mid-June to mid-September when there are fewer birds present). This fascinating phenomenon has occurred here since at least 1980. After nesting, some martins may travel up to 150 miles from their breeding colonies to reach this location. Arriving at sunset, they sleep under the bridge. At sunrise they depart to feed for the day, building up fat stores in preparation for the annual migration back to Brazil.
Why Do Purple Martins Roost Here?
Abundant insects made available by the vast agricultural fields, national wildlife refuges and wetlands of this area support this large population of pre-migratory martins. They roost under the bridge (only along the western end) on its many support structures, I-beam girders and cables. Finally, martins prefer to roost over water where there are fewer predators to contend with.
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Migration
Martins are welcomed back each spring by caring “landlords” who anticipate their yearly return from Brazil. After the breeding season, adults and juveniles from the surrounding countryside abandon their nesting colonies to join together at this pre-migratory staging area before making the 2,600 mile flight back to Brazil. The following spring, martins migrate back to North America and usually return to the same colony to nest again.
Mortality at the Roost
Because traffic flows across the bridge, each year thousands of martins are killed by impact with vehicles. Almost all of the killed birds are newly fledged young. Their bodies are scattered about the bridge surface and are thrown into the water below. Motorists are endangered when they are distracted by hundreds of birds flying into and around their vehicles, even when traveling at slow speeds. To avoid harm to martins, yourself or your vehicle, please take the alternate Virginia-Dare bridge during the hour surrounding sunrise and sunset from mid-June through mid-September.
Marker is on U.S. 64 ½ mile east of Old Ferry Dock Road, on the left when traveling east.
Courtesy hmdb.org
