A Moonbird Among the Waning Red Knots
Posted by Richard Conniff on December 3, 2012
One day in February 1995, on a beach in Tierra del Fuego, a team of researchers equipped with a cannon net trapped and banded 850 shorebirds known as red knots. Among them was an adult male, at least three years old, who would become a legend in the birding world as B95, or Moonbird.
The red knot is a relatively large sandpiper, with a pointy mid-length bill, a dappled brown-and-black back, and in mating season a rust-colored face and abdomen. The way red knots race nimbly along the tide line searching for food apparently reminded the Swedish naturalist Carolus Linnaeus of the Scandinavian King Canute, famous for calling on his royal dignity to keep the tides from washing around his feet.Hence Linnaeus named the species Calidris canutus.
But the real story of the red knot, and particularly of the subspecies rufa, is their extraordinary migratory behavior, which scientists have begun to understand only over the past few decades. Phillip Hoose brings that story up to date in his latest book Moonbird: A Year on the Wind with the Great Survivor B95 (Farrar, Straus, Giroux).
“B95 can feel it: A stirring in his bones and feathers,” Hoose begins. “It’s time. Today is the day he will once again cast himself into the air, spiral upward into the clouds, and bank into the wind. … He has packed all the fuel he can, gorging on worms, clams, mussels, and tiny crustaceans. His inner GPS is set for north. The whole flock is rippling with anticipation. …”
Every spring these birds, “among the toughest four ounces of life in the world,” make a 9,000-mile trip from Tierra del Fuego, at the farther end of Argentina, to breeding grounds on an Arctic island at the top of Canada’s Hudson Bay. Then, having reared a new generation, they turn around every fall and head 9,000 miles south again. (Other red knot subspecies travel from their Arctic breeding sites to South Africa, Australia, India and other southerly destinations.) It is a highly demanding way of life and, not surprisingly, the average lifespan for a red knot is only six or seven years.
B95 was different. He began to intrigue ornithologists because he kept at it year after year, logging enough mileage, someone calculated at one point, to get to the moon and halfway back. Moonbird, as people began to call him, caught Hoose’s interest in 2009 for a somewhat more complicated reason. When scientists first banded B95, they estimated that 150,000 birds in the subspecies rufa were making this heroic odyssey. Today, for no certain reason, the population has plummeted to just 25,000, putting it on a trajectory to join this era’s slow-motion tragedy of mass species extinction. B95, Hoose writes, “is a bird of the Sixth Wave”—that is, the sixth mass extinction in the history of the Earth.
Hoose had been hoping to address the great extinction crisis of our day with an earlier book, The Race to Save the Lord God Bird,about the loss of the ivory-billed woodpecker. The Nature Conservancy, where he is a conservation planner, sent him on the road for a year to bring the reality of extinction home to audiences and deliver a simple message: “Extinction is preventable.” But in the middle of his tour, headlines around the world reported the tantalizing news that naturalists thought they may have glimpsed a living ivory-billed woodpecker in the Arkansas woods.
“After that, the only question anybody wanted to ask was ‘Do you believe? Do you believe that bird was the ivory-billed woodpecker?’ You were damned either way. If you said you believed, you could hear people smirking. If you said no, you were a killjoy.” It left Hoose at a loss: “It was an Elvis-like thing. The bird came to represent something imaginary in the wilderness.” He went off instead to work on a book about a young civil rights heroine, Claudette Colvin, for which he won the National Book Award.
The right way to deal with the extinction crisis, he thought, was to hold out for a poster child, not an entire species, but one individual with a compelling story capable of stirring up powerful human emotions. Eventually, the phone call came from a friend, Charles Duncan, head of the shorebird recovery program at the Manomet Center for Conservation Sciences in Massachusetts, saying, “I think I have your bird.”
By 2009, when Hoose traveled to Tierra del Fuego to begin work on Moonbird, B95 was already at least 17 years old, older than any other rufa Red Knot on record. He had been recaptured three times, most recently in 2007, by a startled scientist, who recognizing him, at first uttered “Oh, my God,” and then went to work, quickly taking all the usual measurements. “His weight was where it should be,” he later recalled. “He had wonderful plumage. He was as fit as a three-year-old. I was holding a superbird in my hand.”
Animals can intrigue us for several reasons, but one of them is how they adapt to all the far-flung, seasonal opportunities of life on Earth. B95 and his fellow rufa Red Knots travel to Tierra del Fuego every November, Hoose writes, because the reddish-brown restinga tidal flats there are packed with juvenile mussels still soft enough and loosely enough anchored “for the tug of a ravenous red knot’s bill.” The long hours of daylight in the extreme south then also mean that the tidal flats are exposed for two brightly lighted feeding sessions a day.
Thus B95 can double his weight until he looks bloated and beady-eyed before migration. It’s mostly fat, which is better for long-distance flight because it packs eight times the energy per ounce as protein. At the same time, B95’s heart enlarges to pump blood to his flight muscles, and he shelves many internal organs: “His liver and gut shrivel, as do the muscles in his legs. His gizzard—an organ that grinds food—decreases in size by nearly half, meaning he will be able to eat only soft food when he stops to refuel.”
These changes also mean that B95 and his flock depend on having the right foods available on his route. But it wasn’t until May 1979 that researchers discovered rufa’s single most important feeding site on the long trip north. The flight from northern South America to the Delaware Bay is almost 5,000 miles long and can last more than six days, much of it across open water. B95 and his flock make the drop into Cape May, N.J., “panting for oxygen, with bones protruding, desperate for food.” To rebuild for the final 2,000-mile run up to the Arctic, these birds must each manage the equivalent of a human gaining 10 pounds a day. Happily, just in time for their arrival, horseshoe crabs are littering the tidal zone with their soft, nutrient-packed eggs.
In the early1990s, however, commercial fishermen suddenly realized that the horseshoe crab mating season in Delaware Bay made easy pickings for the bait trade. “For a few unregulated years, it was a gold rush,” Hoose told his audience during a recent talk at the Yale School of Forestry and Environmental Studies. “Out-of-state vehicles drove up and paid locals a pittance for every horseshoe crab they could gather.” On any given day at that time of year, 90 percent of the entire rufa population can be working the beaches of Delaware Bay, and they apparently felt the competition. Over a two-year period, from 2000 to 2002, half of all adult rufa red knots died.
Around Delaware Bay, some state and local authorities have responded by shutting down beach access during mating season and by limiting the horseshoe crab trade. Argentina has also taken steps to protect wetlands critical to shorebirds. But so far, the effort hasn’t placed rufa red knots securely on the path to recovery.
One new plan now in the works would ramp up the supply of food in Delaware Bay with a form of horseshoe crab egg-banking. University of New Haven marine scientist Carmela Cuomo, Ph.D. ’84, has developed a technique for getting horseshoe crabs to lay eggs in captivity, with a projected harvest of up to 5 million eggs per season. Other researchers have begun placing tiny geolocators on rufa red knots to develop a more complete picture of their migration. Finally, a Delaware Bay student group, Friends of the Red Knot, has launched a letter-writing campaign to get the U.S. Fish and Wildlife Service to list rufa as endangered.
Through it all, even as 80 percent of the subspecies has faded into oblivion, B95 has continued to fly. “How can this one bird keep going year after year when so many of his companions drop from the sky or perish on the beaches?” Hoose writes. Maybe it’s good genes, or good luck, like people who live to 100, he told his audience at Yale. Or maybe B95 just has “a gift for the middle of the flock, so he has protection when the peregrine falcons try to harry a single individual out of the flock.” He is, in any case, clearly a smart, adaptable and enduring creature. “Why would you ever let something like that go?” Hoose said. “You can just let biodiversity go, or you can think of each living species as a survivor, as a triumph, as a success story. The trick is not to wipe them out, but to learn to live with them on their terms.”
Hoose was delivering this message at a Nature Conservancy staff meeting last May, just as his book was being published. Then a text message came in from a researcher back on Delaware Bay. On a whim, she’d gone out on the deck to the spotting scope and trained it on the beach. And as if by magic, there he was, B95, Moonbird, with all of his characteristic markings in perfect focus. A photograph confirmed the sighting.
The text message said simply, “I just saw him.”