With the rise of the full moon Tuesday, purple martins covered the power lines along the south side of Lake Yahola in north Tulsa.
About 1,000 yards of what looked like feathered garlands occasionally leapt off the lines and zoomed through the sky.
To be clear, this was just a portion of the local migrators, avian insectivores preparing for a long flight to the Amazon Basin or to southern Brazil. They stage at Lake Yahola in the early evening hours near sunset. They skim the lake for water and preen on the power lines, but they leave before dark. At twilight, martins from many local areas converge on Tulsa International Airport to roost. That’s where the real show takes place. Yahola is just a warm-up act.
An annual natural wonder that features North America’s largest swallow is underway in north Tulsa and this year they seem to have increased to numbers not seen in at least 10 years, somewhere between 100,000 and 200,000 birds after falling to about 50,000, according to longtime observer Dick Sherry with Tulsa Audubon Society.
And, for once, they found a better place to roost. For the past three years, the birds have been a safety and cleanliness issue for Tulsa International Airport; before that they were a problem for downtown hotels.
Concerns about impacts with aircraft and the need to power-wash the sidewalk to the employee parking lot on a daily basis are not such an issue this year, said Chuck Hannum, Tulsa International Airport chief operating officer.
“We hated to do it but we did cut down a few trees near the entrance,” he said. “Our parking garage construction is complete now, too, and it has a roof so it’s less of an open area. Someone also said the LED lighting on the new roof might have had some effect. Either way, it’s much better now than it was.”
The birds cram together on nearly every limb of every tree in a grove a little less than 80 yards long bordering Airport Drive near the Hilton Garden Inn.
Purple martin fans are gathering at the hotel for dinner and conversation around 6:45 p.m. Saturday and the stepping out to the parking area to watch the birds arrive around 8:30 p.m., said Sherry, who serves as de facto negotiator for the birds with landowners and helps organize the Tulsa Audubon Society’s annual Roost Watch.
“They’ve found kind of a neutral spot this year, I guess,” he said. “It’s nice to see them back in numbers almost like they used to be.”
Even with better numbers, Sherry and other enthusiasts still have concern for the martins. Conservationists worry this late-summer phenomenon could be disappearing nationwide.
The nightly gatherings of the birds here began slowly a few weeks ago. The staging prior to migration is likely nearing its peak this week. It will continue into September as more and more birds take their leave and the numbers dwindle.
With the luck of the weather and atmosphere night after night, watchers may be treated to the sight against red or purple skies, whatever Oklahoma decides to dish up. At first it is a chattering of individuals high in the fading sky, but as they near the roost and the sky grows darker they concentrate and blend into a mass, with a sort of fluctuating hissing, crackling sound, in a throng that moves like an unpredictable cloud. It’s eye-popping organized chaos.
Martin concentrations like this occur in about 100 spots across the country, some small, some large, according to Joe Siegrist, president and CEO of the national Purple Martin Conservation Association.
These birds, the eastern subspecies, have been the subjects of news stories and social media posts in recent days from the New Jersey shore to Minneapolis-St. Paul to Wichita to the Gulf Coast.
What’s unique about the birds is their connection to humans as nearly all of the eastern U.S. population reproduces in birdhouses provided by people. The spread of invasive species — house sparrows and European starlings — led to a decline of the population. Habitat destruction and pesticide use that affects their food sources are ongoing challenges, Siegrist said.
“Overall, the population trend is still downward,” he said. “There are individual states where they’ve had good years, so some are positive and some are negative. The decline seems to be stabilizing somewhat, but we still have areas where there is a drastic decline and other areas where it is tanking and we’re working fast as we can to figure out what’s happening.”
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