South Carolina

Purple martins return to South Carolina with data strapped to their backs

Geolocators placed on purple martins in the late summer before they migrate to South America are removed when they return to South Carolina, with the data collected used to better understand that migration.
Geolocators placed on purple martins in the late summer before they migrate to South America are removed when they return to South Carolina, with the data collected used to better understand that migration. PROVIDED PHOTO

Julie Hovis and Jim Beatson sit back in plastic lawn chairs on opposite sides of an aritifical tree full of artificial gourds in a Sumter neighborhood. Though they look as if they’re simply enjoying the cool April sunset, they’re actually doing scientific research.

They’re waiting for purple martins to make the nightly return to the gourds. Really, one particular purple martin, SC F490. He has a numbered orange band around one leg, and he’s wearing a tiny geolocator attached last year by Hovis.

Data collected in the device will be added to similar data from hundreds of birds throughout North America. The research effort, begun in 2007 by Bridget Stutchbury at York University in Toronto, is designed to give a better understanding of the amazing migration habits of these members of the swallow family.

The geolocators cost about $200 each, and researchers helping with the project are encouraged to solicit sponsors. Hovis rounded up sponsors the first two years of the three she volunteered to do the work. This year, she’s covered the cost for several herself. An endangered species biologist working out of Shaw Air Force Base, Hovis is doing the trapping to help colleagues … and because she loves the little birds.

Early results from the study indicated purple martins fly more than 300 miles per day as they zip from North America to Brazil. More recent data shows some birds take longer, covering the 800 miles to Mexico in two days and hanging around there for a few days before finishing the journey. One lingering question is where the birds do their molting.

F490 could have some of the answers, but he doesn’t seem to want to give them up. Hovis and Beatson have been stalking him since first sighting him nearly three weeks earlier. In the meantime, they have captured eight others of the 27 birds they equipped with geolocators last year.

To capture F490, they need him to enter one of the two-dozen gourds hanging in a man-made complex next to a small pond next to a street where families are walking their dogs. But F490 can’t seem to make up his mind which gourd to call his (and his mate’s) own. Each night, he lingers outside the gourds until after dark, when it’s too late for Hovis and Beatson to make a good ID and know which gourd to check.

F490 is up to his old tricks on this gorgeous, cool night. As others of the 40 or so birds in this roost enter gourds, he hangs around outside. Only about 20 feet away, Hovis and Beatson keep focused on him with their binoculars. Then he flies away. Then he comes back.

Finally, he slips inside a gourd. “He just went in 12,” Hovis said in what came out as half excited statement, half question. Beatson answers with a confirmation.

Hovis jumps up, grabs a long-handled net, and puts the net over the opening in the gourd, just in case F490 decides to try to escape. Beatson pulls a tall ladder over to the gourd tree, covers the hole in No. 12 and disconnects the gourd from the tree.

Across the street in the back end of Hovis’ SUV, she reaches into the gourd and gently removes F490, then Beatson removes the female in the gourd and sets her free.

Now comes the science part. Hovis carefully removes the geolocator. This one was more difficult to slip off than most. In the early years of the project, researchers worried the geolocators, though amazingly light, would bother the birds enough to impact their health. On the contrary, F490 has gained so much weight the geolocator device strap has grown tight on him.

“I’m sorry fella,” she says as she struggles to cut off the device.

With Beatson’s help, Hovis measures the wings (150 millimeters), snips the end of two wing feathers and pulls out a tail feather. Then she puts the bird in a small cloth bag and weighs the bag on a small scale. He weights 56.3 grams.

Through it all, F490 makes not a single peep. For a bird that flits around busily for hours each day chasing bugs, he’s amazingly still.

With all the data entered and the feather pieces tucked into small envelopes, Hovis paints the orange band on his leg green with fingernail polish to indicate he has done his scientific duty. Then she sets F490 free again, apologizing to him once again for the inconvenience.

Where will they roost

▪ Later in the summer, F490 and the purple martins in the small Sumter roost will begin gathering along with hundreds of thousands of others nightly at a regional roost.

▪ Last year, the main post-nesting roost spot in the Midlands mysteriously shifted from Bomb Island in Lake Murray to an unnamed island in Lake Monticello.

▪ Scientists and bird lovers can’t wait to see if the roost will return in July and August to Lake Monticello or maybe hop back to Lake Murray.

  Comments