The mass migration of purple martins from their various breeding grounds in North America has concluded. In late summer every year, they aggregate en masse, flying south to Brazil, Argentina, and Bolivia where they overwinter in the dense canopies of the Amazon rainforest.
Along the way, they stop to rest in large roosts where up to half a million birds will descend on a handful of live oaks in parking lots across the southern United States, drawn to the protection against predators afforded by urbanized environments.
For the past two years, the local roost has taken place in Round Rock, drawing crowds of ardent admirers and avid bird watchers armed with umbrellas to ward off the bombardment of organic precipitation, an inevitability when standing under thousands of swarming birds who've just finished their evening meals.
When they return for the breeding season early next year, they'll be on the lookout for comfortable places to nest in. Purple martins are cavity nesters and historically have laid their eggs in dead trees, where woodpeckers had carved out holes for themselves that they later abandoned.
But beginning with Native Americans, humans have forged a bond with these birds that continues. The Choctaw and Chickasaw would put out hollow gourds for the martins to nest in. The birds, in turn, would chase away marauding crows that would otherwise have pilfered their fields of corn and curing meats.
In the 1850s, the English sparrow and European starling, also cavity nesters, were introduced to the U.S. More aggressive than purple martins, these invasive birds quickly began taking over the natural cavities the martins relied on, causing their numbers to dwindle.
Were that the end of the story, purple martins might be a rare site in eastern North America. But the awe-inspiring roosts containing hundreds of thousands of birds suggests that the martins are doing better than might otherwise have been expected. That's because bird enthusiasts and nature lovers from across the country have begun emulating the old practice of putting out houses for the martins to nest in.
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There are several such martin houses that dot the Austin landscape, but one of the most recently to be established was at Patton Elementary School in Southwest Austin, where an enterprising fourth grader hoped to attract martins to his campus, according to the Austin American-Statesman .
Kieran McDonal went out to last year's roost in Round Rock, where Travis Audubon was hosting its annual purple martin party. Kieran became enamored with the birds and decided he'd try to make a habitat for them at his school. He pitched his idea to the elementary school's environmental group, which teaches students about nature and science by having them grow plants, take care of animals and even monitor the school's power consumption.
"So what I did is, the rest of the summer I created a presentation with facts about purple martins and presented it to the ecoteam, and we decided that we wanted to have a purple martin colony," Kieran said.
The group loved the idea, but purple martin houses aren't cheap. While you can simply make your own by carving an entrance to a hollow gourd, these often leave the martins inside susceptible to predators, such as snakes and hawks. It's generally better to purchase purple martin homes with built-in protection.
Kieran initially set out to purchase six martin homes. So together with fellow team member Charlotte Sigler and fifth grade science and social studies teacher Michael Massad, Kieran started a fundraiser that got his entire school involved with the project.
"The idea is that we'd get money from all the classes. But if your class raised the most, you got to name one of the gourds," Kieran said.
Kieran was so successful in garnering funds that he actually raised about twice as much money as he initially intended to, which he used to buy six additional bird houses, which meant everyone got to name one. And with a school full of elementary students, you can bet there were some eccentric choices.
Names like Purple Martin Penthouse and Barajas Bulldog Bungalow were written along the side of each house. Others were more tongue-in-cheek, like The Note House, an `air' B&B, while others settled for grandeur spiked with alliteration, like the Purple Palace and Martin Mansion.
But Kieran's persistence didn't end there.
Purple martins are extremely social birds, and it can be hard to attract them to a new area if there aren't others around for them to engage with. So Kieran worked with his dad, Michael, to entice errant martins using subterfuge. Using an iPad connected to a power bank, they blasted recordings of purple martins out on the school grounds.
"Every few days we'd go back and recharge it," Kieran said. This went on for about two months, from February through April of this year, all under Kieran's watchful eye. "You have to go and check the gourds every five days. You take down the gourds and look at all of them and try to see if there's any evidence of purple martins, and in our case, change out the battery."
Kieran's persistence was rewarded when a small flock of martins decided to make the Patton campus their home. The birds laid a total of 45 eggs. That's when the real work began. Kieran could have simply appreciated the birds from afar, but to make sure a colony is healthy, they often need intervention.
Even if they've established a nest in a birdhouse, purple martins are at risk of being evicted by sparrows and starlings. Sparrows will peck holes in martin eggs to take over the nests for themselves. Starlings are even more aggressive and will kill both adult and fledgling martins to secure the nest.
"We had two starling nests, and one of them had eggs in it," Kieran said. "Later, we had house sparrow problems with a couple eggs. We took the nests out with the eggs in it and stuck it up in one of the trees."
They're also prone to mites.
"You have to check on the nestlings because sometimes they get nest mites that get in their wing feathers, and sometimes they can cause disease and eventually death," Kieran said. Whenever a nest was found to contain mites, the fledglings were removed and the old material replaced with fresh leaves.
By the time summer had rolled around, a total of 20 fledglings had successfully matured and were ready for their first migration to the Amazon. As for Kieran, he's moved on to someplace new as well, just not as far: As a fifth grader, he's attending intermediate school.