Purple Martins Come Back to the Outer Banks Each Year

By Carolina Designs Realty on Jul. 20, 2021

Header photo credit: Coastal Carolina Purple Martin Society

Each year, Purple Martins return to the Outer Banks as they follow their migration route between South America and North America.

The Purple Martins around the William Umstead Bridge are back again. In some ways, they resemble the swallows of San Juan Capistrano, the well-known birds that come back annually to roost at the California mission.

That comparison fits, since Purple Martins are swallows—the largest swallow species in North America. Like those birds on the west coast, they migrate long distances and revisit favored nesting places year after year.

Their trip to the Outer Banks begins far away in Brazil and other northern areas of South America. Scientists had long suspected these migration routes, but only recently did satellite tracking confirm them, and many questions remain. It took years of study simply to identify the migration pattern. One unresolved point is whether individual birds come back to the very same nesting locations each year.

The William Umstead Bridge is the older US 64 bridge at the north end of Roanoke Island. Since it opened in 1955, Purple Martins have had 60 years to settle into this location. They have adapted so successfully that more than 100,000 spend their summers at the bridge. As a result, since 2007, NCDOT has lowered the summer speed limit on the bridge to 20mph.

Purple Martins are remarkable swallows. Despite the name, their coloring is not truly purple; it is a dark blue-black with an iridescent sheen. Depending on the light, they can appear bright blue, navy blue, green, or sometimes a rich deep purple.

Seeing Purple Martins fly is like watching aerial stunts mixed with a race. They are exceptionally nimble and can reach 40 mph, plunging from 100’ to 150’ to glide over the water, drink, and rise back into the sky.

They feed on insects, including moths, gnats, flies, and mosquitoes, though they do not consume as many mosquitoes as their reputation suggests. Because Martins generally feed between 100-150’, they often fly above the altitude where most mosquitoes are found.

Even so, their hunger for insects is likely the reason their earliest human-made homes were dried gourds hung by Native Americans near crop fields.

European settlers carried on that practice after arriving. Purple Martin houses are still familiar in backyards today, although insect control is no longer the main reason people provide them.

Why do so many Purple Martins live at the Umstead Bridge?

Away from hanging gourds and backyard martin houses, Purple Martins naturally live colonially, gathering in large groups or colonies. The estimated 100,000 birds that use the bridge is unusually large, but not without precedent. Colonies of 700,000 have been documented.

Some aspects of their nesting behavior remain uncertain, though researchers have learned a few things. Females select mates according to the nest site a male has chosen. Two females sharing one nest is uncommon, but it does happen. Genetic testing has also shown that both male and female Purple Martins may mate outside the pair bond.

On the East Coast, Purple Martins rely almost entirely on human-made nesting places, including bridges, buildings, and Purple Martin houses. The pattern differs on the West Coast, where Martins most often nest in dead trees, saguaro cactus, cliffs, and larger woodpecker holes.

In the fall, after the chicks have matured enough to complete the 9000-mile flight to Brazil, the Purple Martins will depart Roanoke Island. Then, sometime the following spring, they will come back.

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Carolina Designs Realty

Carolina Designs offers quality, well-maintained vacation homes. Its collection includes 350+ properties, ranging from smaller getaways to reunion-ready rentals with 15 bedrooms or more. Guests can choose oceanfront, sound front, or locations in between, with homes positioned for prime settings and convenient beach access. Visit https://www.carolinadesigns.com/.