The Purple Martins of Lunch Island

Iconic Communities, On the Road, Seasonal, Traditions
on May 20, 2001

About four days a week, depending on the season, Bill Morgan of White Rock, S.C., rises before daybreak and heads out on Lake Murray, where he’s fished since 1961.

In the quiet dawn, Morgan may encounter a few other fishermen—and if he’s lucky, some largemouth bass, crappie, or stripers. Come summertime, though, Morgan will have a lot more company on his early morning trips to the lake, especially if he heads his bass boat out to Lunch Island, a 12-acre mass of scrub, trees, and grass situated in the heart of Lake Murray.

It’s where the purple martins, hundreds of thousands of them, come to roost.

“The sky looks solid black,” says Morgan of the purple martins’ arrival at Lunch Island in June. “They look like an upside down tornado.”

The purple martins roost on Lunch Island, usually until late August or early September, when they make their migratory flight to South America for the winter.

Each day during their summertime stopover at Lunch Island, the purple martins exit the roost en masse before sunrise to snap butterflies, Japanese beetles, dragonflies, and other insects from mid-air.

“It’s like an explosion,” says Dr. Kevin Russell, regarding the purple martins’ early morning exodus. “The martins are in equal densities, going in all directions.”

At sunset, the purple martins return to Lunch Island, making a dramatic entrance by building up into a funnel and swooping down to roost in a counter-clockwise fashion.

A wildlife research biologist at Willamette Industries Inc. in Dallas, Ore., Russell studied the Lunch Island roost in 1995 while working on his master’s thesis in zoology at Clemson University.

Twice each weekday, from June 30 to August 27, he made visual surveys of the purple martins from a peninsula on the south shoreline of Lake Murray to determine the movements and size of the roost.

After each survey, Russell visited the National Weather Service office at the Columbia Metropolitan Airport to obtain radar images that coincided with his visual surveys.

“We were looking up at the sky at a fixed area and were counting the birds as they passed over,” Russell says of the visual observations. “Then we were relating it to the density on the radar screen.”

During July of 1995, Russell estimated the total roost population numbered at least 700,000 birds, possibly the largest purple martin roost in the world.

Purple martins, the largest type of swallow in North America, are about 7.5 inches long and weigh 1.9 ounces. The males are solid black, which gives them a glossy, purple appearance in the sun. By comparison, the females and young adult males have a duller coloring.

In the western United States, purple martins usually nest in abandoned woodpecker nest cavities. In the east, the martins depend on humans to build them condominium type houses made of wood or gourds.

Each year, usually in February, Morgan puts up 20 gourds in his yard for returning purple martins, being careful not to place the gourds too close to tall trees. The martins go there to breed and stay until their young fledge, then fly off to Lunch Island to roost for the summer.

“They like being high up, not hemmed in by tall trees,” says Morgan, who believes the absence of tall trees on Lunch Island, which was used by World War II plane crews for bombing practice, was a draw for the birds.

Even though Morgan and others have seen some purple martins on Lake Murray for decades, most people were not aware of the purple martin roost—or its size—until the late 1980s or early ’90s.

Indeed, until just seven years ago, Capital City/Lake Murray Tourism staged its July Fourth fireworks display on Lunch Island.

“And July is the peak time for the purple martins to roost,” says Miriam Atria, the tourism organization’s director. As the scientific community and the general public became more aware of the roost, the fireworks display was moved to another Lake Murray island.

The purple martin roost certainly has attracted people to the area, Atria says.

“Nature-based tourism is growing,” says Atria. “Individuals from all over the U.S.A. have visited the area.”

And measures have been taken to ensure that the martins continue to return to Lunch Island each year. In 1995, the South Carolina Department of Natural Resources, the Columbia Audubon Society, and the South Carolina Electric and Gas Company, which owns Lunch Island, signed a joint agreement officially designating the eastern end of Lunch Island as the nation’s first purple martin sanctuary. Now, signs make visitors aware of the roost, and loud activities, such as the fireworks, are no longer allowed.

That puts bird watchers like Bill Morgan at ease. In November, he will remove the gourds from his yard and clean them in preparation for the birds’ return next year—something he eagerly awaits.

“I enjoy watching them. They’re beautiful.”