CCB tracks another surprising whimbrel migration
Catching whimbrels on their breeding grounds in the Arctic Circle is quite different from trapping those same birds in their mid-migration staging areas on Virginia’s Eastern Shore.
There are some superficial similarities, though, says biologist Fletcher Smith.
“It looks an awful lot like the marshes of Virginia up there,” Smith said. “Huge expanses of marsh surrounded by willow bushes.”
But research on the Mackenzie River in far northern Canada presents challenges not to be found when you’re working on the creeks and marshes of the Eastern Shore. Smith carried a Remington 870 shotgun, loaded with slugs and cracker shells to scare off the bears. Bears were a worry, but the mosquitoes were a dreaded daily presence.
Hoping for a high-wind/mosquito-free day
“We didn’t have any bears in camp, luckily. But they say the mosquitoes up there are as dense as any place on earth, including the Amazon, so every day you have to work in full bug gear covered head to toe,” Smith said. “There’s that buzzing around you, so you just hope for high-wind days that kind of knock the bugs down.”
Smith’s trip to the Mackenzie River was the latest effort in the Center for Conservation Biology’s study of the migration of whimbrels. Since 2008, CCB researchers have been using solar-powered transmitters to rewrite the natural history of these extreme fliers. Whimbrels winter down the coasts of South America and breed in the far north. The birds have made a stopover hub on the Eastern Shore for both northward and southward migrations, resting up and feeding on the abundant fiddler crabs.
Until this year, the CCB had caught whimbrels on their staging areas on the Atlantic Coast, principally on the Eastern Shore. Birds fitted with the light backpack transmitters almost immediately began to deal surprises to the scientists, beginning with a bird named Winnie’s nonstop 3,200-mile flight from the Eastern Shore to her breeding grounds.
Trying to understand the migration strategy
Winnie and other whimbrels challenged traditional ornithological understanding of the species’ flight and navigational capabilities. Bryan Watts, director of the center, explained that sending a researcher to the breeding grounds was the next step in refining the understanding of migratory strategies of the birds.
“There are three populations. There’s one that breeds on Alaskan North Slope, one in the Mackenzie River, and then there’s one in Hudson Bay,” Watts explained. “We always thought that the birds coming up the Atlantic coast were the ones in Hudson Bay until we tracked Winnie and Hope over to the Mackenzie area.”
Selecting birds to carry the transmitters right on their breeding grounds will allow the researchers to follow the migratory journeys of the birds known to belong to the Mackenzie River group, he continued.
Despite the continual threat of bears and the daily battles with mosquitoes, whimbrels are much easier to trap on their breeding grounds than when they’re loading up on crabs in tidal marshes of the Eastern Shore. Staging whimbrels are wary and usually are caught by shooting rocket-nets over birds.
No rocket-nets required for breeding whimbrels
Smith explained that the nesting whimbrels are territorial, keeping other whimbrels—and predatory birds—out of their area. There’s typically 500 to 1,000 meters between nests, he said. The birds are concentrating on breeding, so rocket-nets are not required.
“You catch them with a walk-in trap. You just place trap—basically a chicken-wire trap—over the nest,” Smith said. “And then you go back maybe 50 to 100 meters and wait in a blind for the bird to actually go in the trap, and then you run up and catch it.”
Three of the birds Smith fitted with transmitters this summer continued the great whimbrel tradition of doing something totally unexpected: Four of them flew a previously unknown migration path straight down the center of the Atlantic. Watts said at times the birds, named Mackenzie, Taglu and Akpik, were 1,000 miles closer to Africa than to North America.
The southward fall migration often holds some drama for whimbrel trackers. Last year, a number of birds overcame the challenges of migrating during Hurricane Irene by employing a variety of strategies, ranging from flying straight through the storm to hunkering down until it passes. Surviving a tropical storm doesn’t mean that a whimbrel’s worries are over, though. Birds named Machi and Goshen, after negotiating the dangers of Irene, were gunned down in the “shooting swamps” of Guadeloupe.
This fall, a bird named Pingo proved to be another storm conqueror, landing safely in Brazil, after deftly dealing with Hurricane Isaac near the end of a marathon migration leg, taking a similar mid-Atlantic route as Mackenzie, Taglu and Akpik did earlier.
Let us now praise famous whimbrels
The public has shown considerable interest in the migratory adventures of these extreme fliers. Science and wildlife blogs, as well as the mainstream media, have followed the triumphs and tragedies of Winnie, Chinquapin, Pingo and some of the other more intrepid whimbrels. The CCB has made it easy for bloggers, reporters and the general media to follow the flights of whimbrels through a set of web-based tracking maps that plot the location of each of the birds on active migration.
Watts notes that the community-outreach component of the whimbrel study is important in raising public awareness of the greatest danger facing the declining population of whimbrels—habitat loss. The cosmopolitan whimbrels are intercontinental travelers, but Watts said that CCB research has shown that the success as a species is tied to a few comparatively small areas of land. Many parts of these areas—breeding grounds in the far north, wintering areas in Central and South America and stopover areas like the marshes and creeks of the Eastern Shore—are threatened by pressures ranging from residential development to aquaculture to oil and mineral exploration.
“This is a species that is shared. We see these birds here in Virginia and consider them ours, but they migrate to other places,” Watts said. “Those birds are breeding on the Mackenzie, they’re flying over Canada to the east coast of the U.S. People all along the way see these birds. Then they’re down in Brazil with a different group of people. Maybe these birds represent a possibility of making the cultures work together towards some kind of common conservation goal.”
