Catching the elusive whimbrels

"The birds are here," Libby Mojica said, as a pale dawn lit up Box Tree Creek on the Eastern Shore. The only birds in sight were gulls, and she didn't mean those.

"Slowly, as the tide comes in, the birds will start moving on to these mud flats," she said, as two clapper rails performed their strange little hop and scurry across from the dock, but she didn't mean those, either.

Out in the marsh, in the distance, little heads could be seen moving around. They belonged to biologists from the Center for Conservation Biology and The Nature Conservancy, who were slogging around in hip waders, running blasting wire through the reeds.

"The birds are on the move now," Fletcher Smith said when he got back to the dock, and what he meant were whimbrels, long-legged shorebirds weighing about a pound each - and that's a fat one - that can fly an amazing 3,500 miles nonstop.

The biologists didn't know that until two weeks ago, when a whimbrel named Hope landed in the Virgin Islands, carrying a satellite transmitter that had been attached at Box Tree Creek. They wanted to know more.

Four rocket-powered nets. Six biologists. Two speedboats.

The task: Catch four whimbrels. The question: Who has more endurance - scientists or shorebirds?

 

Whimbrels spend about three weeks on the Eastern Shore each spring and late summer, feasting on fiddler crabs. Virginia is a rest stop on their interstate and international flights, where they take on fuel, doubling their weight. Their long, curved beaks are exactly the same length and shape as the burrow of the southern fiddler crab.

There appear to be two world populations of whimbrels - one in the West and one in the East. Until 2008, it was assumed that the twain never met, but the satellite transmitters changed all that - a bird named Winnie flew from Box Tree Creek, which is near Machipongo, to the north slope of Alaska in May that year, a distance of about 3,200 miles.

"Now we're finding that both populations are going through Virginia," Mojica said.

The Center for Conservation Biology, which is connected to both the College of William and Mary and Virginia Commonwealth University, has studied whimbrels for 10 years. The birds' population has dropped about 50 percent in that time, prompting more in-depth studies to find and protect their most important habitat. Thanks to the $2,000 solar-powered satellite transmitters, that habitat appears to be the Eastern Shore, where millions - billions? trillions? - of fiddler crabs provide body fat for those long-distance flights.

Whimbrels and many other birds don't like to get their feet wet. At high tide, most of the marsh floods, leaving only a few spots above water. On these points the biologists put nets, folded into wood boxes and connected on either end to rockets, lightly camouflaged with bundles of fresh marsh grass.

Then they back way off, to watch through binoculars and high-powered spotting scopes. When birds have clustered in front of the boxes, the biologists motor quietly to the reel of blasting wire, connect the trigger and set off the rockets.

This works well in theory. But whimbrels are among the wariest of birds. The scientists have learned through trial and error that whimbrels don't trust bundles of dead marsh grass, they don't like the noise or look of boats and they choose not to stand in front of wooden boxes if there's a nice bit of vacant marsh elsewhere, say, to the side or rear of the box.

"We have a whimbrel flying over the trap site," Smith reported Aug. 19 from behind his binoculars at the dock, watching the mud flat where Winnie had been captured. "It wants to land. It landed and it's in front of the box."

This is called a confidence bird. Other whimbrels, seeing it unmolested, will be attracted to the same site. The biologists want just the right number of fat birds before firing - too many, and birds could die of stress before they can be released from the net; too small, and they can't carry the transmitters.

By 7:10 a.m., a cluster of confidence birds, mostly gulls, had landed, but no whimbrels.

A sharp, three-note call made the binoculars swivel to the right.

"That's the whimbrel flight call," Smith said. "The bird is in flight and unhappy about something. Trying to find a new roosting site. Aaaand - flying away."

Mojica checked the time: 8 a.m. High tide. The whimbrels would start to disperse with the falling tide. Smith took the boat out for a closer look, but only one bird was on the flat, and too far from the net. He reversed course and headed for the creek mouth, where he discovered 21 whimbrels standing on a bit of high marsh on Webb's Island. As the boat idled, three flew away.

"Nice, big, fat birds," Smith said, easily able to carry the 9.5-gram satellite transmitter. The nets would be moved there.

 

Two birds were caught, fitted, named Machi and Pongo, and released, but the biologists needed two more. Hurricane Bill promised easy pickings, with extraordinarily high tides forcing birds to congregate on the highest roosts, so last Sunday, they moved the net off Winnie's mud flat to a higher spot farther south, and put three more on Webb's Island.

"I think it's promising for today," Smith said. Long before high tide, the usual mud flats were underwater and the dock was cut off from the road. The winds that blew the water in also made for good migration. Many whimbrels, fattened and rested, would be ready to ride them south.

In May, the biologists had tagged a bird they named Hope. She flew to Hudson Bay in Canada, then to Alaska, to the western breeding grounds, then back to Hudson Bay. On Aug. 10, Hope took off on a 3,500-mile nonstop flight over the Atlantic, passing east of Bermuda, finally landing on St. Croix on Aug. 14. She had traveled 13,000 miles since May.

As the water rose, 45 whimbrels gathered on Winnie's mud flat.

"Well, they can't stay there forever," Smith said, lowering his binoculars. "They're going to have to move when the tide comes up." He watched the water flowing past the dock for a minute. "That's as fast as I've ever seen the water come in," he added.

Jethro Runco arrived, splashing down the road in hip waders. "Look at the tide!" he exclaimed. "Holy smoke!"

"Those whimbrels are up from Winnie's spot," Smith reported. "Just gotta give it time. It's a virtual guarantee" - and right about then, someone discovered that the van wouldn't start. Everyone splashed back to the parking spot to look for jumper cables. The van had to start. Once whimbrels were netted, they would be rushed back to the air-conditioned van. Stressed birds overheat quickly; they would be held in front of the

A/C vents while they were measured, weighed and, hopefully, fitted with transmitters.

While the van was repaired, the water rose. And rose. And rose.

By the time the boats left the dock, about 100 willets - another type of shorebird - stood directly in front of the net, too many to untangle and release at the rate the water was rising. Twenty whimbrels stood just out of reach. Part of the net was already underwater.

Smith decided to flush the entire flock, hoping whimbrels would land first, and the net could be fired. But the willets were faster, and soon the rocket charges were underwater and useless.

The biologists headed for Webb's Island, where the water was so high that shorebirds were perching in small shrubs behind the net boxes, and it wasn't even high tide yet.

"I feel like crying," Shannon Ehlers said.

"That's extremely, extremely disappointing," Runco added, and silence fell for a few minutes. "Disappointing," he repeated, but Smith had his binoculars back up.

"We're gonna shoot," he said. "There's a bird in front of the box."

Mojica started downstream to the reel of blasting wire, but Runco shouted, "Stop! It's flying away!"

"Should we just go hang out by the blast box?" Mojica asked, but Smith feared that was too close to such wary birds.

"Darn it!" he exclaimed. "So close." They anchored the boats and waited, discussing what they would name the transmitter birds when they caught them.

"Patience and Persistence," Ehlers suggested, and the tide kept rising until the Webb's Island nets were useless as well.

 

The next day, Smith decided he was being too cautious. Instead of watching from the dock, he sent one boat to each blast box, with radios for communication. The rockets had been placed on wooden platforms - a risk, since the whimbrels might avoid something different on the marsh, but necessary to keep the charges dry. Two hours before high tide, the boats were in position.

"So now we wait," Mojica said, and tested the radio. "Hey, you guys, can you hear me?"

No answer.

Four whimbrels flew onto the Webb's Island marsh, just beyond the catch zone. The radio crackled: "Libby, we may have a shot," but a few minutes later Smith called back a negative. Mojica radioed to say more whimbrels had landed at her site, but again there was no response. She motored slowly up and down the creek, looking from different locations, trying not to alarm the roosting birds, debating whether they were within reach of the net.

An explosion rang out from the south, but Smith's shot had missed. That net now useless, his team would move to Webb's Island, and hope.

The boats anchored side by side. The tide rushed in, still higher than normal. The birds could be heard calling to each other, and gulls would fly up, then settle again.

"They're getting antsy," Smith said. "The water's getting up."

Seven more whimbrels joined the 20 already on the high marsh. The rising water had flooded the ground directly in front of the net boxes. No possible shot. Smith hoped the birds would spread out as the tide began to fall.

The noon sun beat down. A bottle of sunscreen changed hands. Sandwiches were passed around. Two more whimbrels flew in, then three. Another flock landed, out of the catch zone.

Thirty minutes passed. "They're getting antsy," Smith said again, and Runco, getting antsy himself, suggested moving closer, to where two reels of blasting wire, each connected to a different net, were hooked on a post. He slipped into the water, trying not to splash, and carried the orange reel to Mojica. One whimbrel flew away. Smith backed off to wait again, leaving Mojica with her finger on the trigger of the orange reel.

The radio crackled. "We are soon going to have a shot on three birds, so be ready," he said. Fifteen minutes dragged past, with no signal.

"Libby, do you think you could grab the yellow reel out of the water?" Smith said softly over the radio. "I'll let you know which one to shoot."

She waded over and retrieved the second blasting line as quietly as possible, climbed back into the boat, connected the trigger, and sat poised.

The radio stayed silent. She looked over her shoulder at Smith's boat, where every pair of binoculars was trained on the marsh. She looked back at the net boxes. Still no signal. She turned to look at Smith again, shrugging her shoulder and holding out her left hand in the universal signal for "What?"

Runco would later report that Smith had been repeating, "Fire! Fire yellow! Fire!" into the radio and wondering why Mojica didn't hit the trigger, but as he saw her gesture, Smith punched his fist into the air and she fired.

A small blast, the net shot out, a cloud of birds rose screaming into the air, Smith's boat shot past at high speed with Runco and another biologist crouched low in the bow, arms spread over the chicken crates to keep them from flying off. Mojica gunned her motor and followed, Smith grounded, Runco leaped into the thigh-high water and ran.

"We've got two!" he shouted, and within just a few minutes the whimbrels were crated, loaded and hustled back to the dock and the air-conditioned van, where the blower was on the highest setting.

One bird was too small, but the other was fitted with a satellite transmitter and named Webb for the island where he was caught. A few feathers were plucked for stable isotope testing, which will tell whether the bird is from the East or West population. Leg bands were attached and then both whimbrels were tossed back into the air, and last seen flying south.

The crew prepared to retrieve the nets and bring them back to dry. They would reinstall them on the high marshes next day.

"Three down," Smith said. "One to go."

Diane Tennant, (757) 446-2478, diane.tennant@pilotonline.com