Unraveling the mysteries of migration
Wanted: Aventurous people to spend 10 days on the remote beaches of Peninsula Valdes, Argentina. Expect hard work, up to 18 hours a day. Accommodations: a stucco camp and rough-hewn log cabin. No piped water. No heat. Probably no refrigeration. Beware of rattlesnakes, spiders, and scorpions. Pay your own way -- approximately $4,800.m
Armed with these less-than-enticing tidbits, the Manomet Bird Observatory recently set out to solicit volunteers for a research trip to the parched coastal area of central Argentina. the response: Unrestrained enthusiasm.
The lure for such a seemingly somber journey revolves around a plump, finicky , spike-nosed bird called the red knot. This tireless voyager, a type of sandpiper, is one of the longest migrating birds in the world. It hopscotches from the stony tundras of the Arctic to the bleak stretches a long the southern tip of South America.
Slightly larger than a robin, it also boasts the rare feat --or foolishness, depending on you feeling about heights -- of carrying out its long-distance journeys at altitudes of up to 20,000 cloudy feet. Most normal migrants are content to plod along at a mere 3,000 feet. With pit stops, the red know makes the entire voyage in less than three months. Even more unusual, the bird will log 2,000 to 3,00 miles at a hop -- sometimes covering the distance in less than 80 hours.
"They probably have some of the logest nonstop migrations among birds," biologist Brian Harrington of the Manomet Bird Observatory here trumpets.
all this makes the red know of particular interest to scientists, who are trying to lear more about the marathoner to help protect its small population. The research may also yield important clues about the impact man is having on the environment and its affects on other animals as well.
The Manomet Bird Observatory is one of only three major private, nonprofit observatories in the country. It sits on 18 acres of shrub-studded glacial upland on the outskirts of Plymouth, Mass.The building itself is a house-turned-research-center anchored on a grassy bluff overlooking Cape Cod Bay.
Eleven observatory members will set out at different times in March and April on a Sherlock Holmes-style hunt to find out more about know migration patterns and habits. Two of the members, Mr. Harrington and biologist Linda Leddy, are professional researchers. The rest are intrepid bird enthusiasts. The group is expected to be joined in Argentina by a researcher from the Canadian Wildlife Service.
Fortified with rocket-launched nets, they plan to stalk the gray or red-ocher birds (depending on the season) among the scrubby salt beds of coastal Argentina , 600 miles south of Buenos aires. Their goal: to snare and tag several hundred of them, which will then be watched by a network of bird "spotters" up and down their North-South American flyway.
Red knots, once almost wiped out by hunters looking for food, have been replenishing their ranks ever since the early 1900s when legislation was passed here and in Canada protecting them and other shorebirds. Today they are believed to number between 50,000 and 100,000 -- a number still considered small by bird census standards. European knots, for instance, total more than 400,000 .
Now they face another threat: coastal development. Increased activity, in the form of everything from oil drillers to beachcombers, is encroaching on the birds' few select stopover points and may be disrupting their migratory patterns , the researchers say. By finding out more, the Manomet group hopes to keep them off the rare species list.
"Pardon the expression," Mr. Harrington says of the encroachment, "but we think they're sitting ducks."
Bird migration, one of the most spectacular phenomena in the animal world, has fascinated man for centuries. No less weighty thinkers than Aristotle and Pliny the Elder have puzzled over their seasonal disappearance. A few less weighty thinkers have given it some thought, too. One early theorist, for instance, suggested that birds spent their winters on the moon. Another postulated tht they buried themselves in mud and hibernated.
Today the study of migration is in full plumage. Although the cause and mechanics of bird migration remain shrouded in mystery, ornithologists and other scientists have begun hardening several theories. Experts generally agree that birds use several navigational aids to guide their travel. Like the ancient mariners, some are believed to chart their course by the sun, moon, and stars. some, too, are believed to use their acute sense of sight, smell, and sound to help recognize natural landmarks. Birds' sensitivity to the earth's magnetic field and gravitational pull may also play a part.
But why head north or south, as the seasons dictate, anyway? The reason revolves more around food than any keen desire for a balmy winter vacation. Probably taking their cue from shorter days and colder nights, more than 10 billion birds in all are believed to wing north each spring in search of more plentiful food. The number jumps to 20 billion for the southern migration in the fall, when the parents are joined by their offspring. Aming these huddled masses are the red knots.
"Most of us think of birds as migrating to get away from something," Mr. Harrington, a bird buff since childhood, says. "But shorebirds are migrating to get to the next good patch of food."
The Manomet group will focus on where the red knots travel instead of how they do it. The portly birds undertake an odyseey each year that would have tired Marco Polo. First to leave are the females, which take off from the icy northern reaches of Canada's Hudson Bay in July, leaving the males behind to care for the young, until August, when they join their mates. The young, having never ventured beyond the roost, trundle along in September -- unescorted.
First sotp is Canada's James Bay, where the birds fatten up on a menu of clams. Other knot delicacies along the flight inclure mussels and, when in season, horsehoe crabs. They devour enough to double their weight -- all of which is lost on the next leg of the journey. The second stop centers on one of two general areas in the United States: the shores of Massachusetts, including parts of Cape Cod, and the New Jersey coast. From there is is on to feeding grounds in Surinam and French Guiana and eventually on to Tierra del Fuego, at the southern tip of south America. They arrive at these final roosting areas in late fall. The birds retrace the path northward starting in March.
Harrington and company plan to catch the birds at one of the first stops on their northern migration, at Peninsula Valdes. By capturing and marking the birds there, the researchers hope to unravel one of the gnawing mysteries surrounding the red knot: why a splinter group treks inland, over the hardscrabble plains of Texas, and eventually roosts in Saskatchewan instead of Hudson Bay. They also hope to discover why some of the birds cluster along the east coast of Florida during their southern migration instead of going on to Argentina.
All this, of course, cannot begin to be answered until they have actually snared some knots -- which is no small chore. It requires the cunning of a polecat and the patience of a guard at the Tomb of the Unknown Soldier. The process takes hours, even with the use of a rocket-launched nets. At Peninsula Valdes, the sneak attack will take place at high tide when the knots roost shoulder to shoulder along the shore. The gregarious birds sometimes huddle together in groups of several thousand, bobbing to and fro like a moving carpet.
About three hours before roosting time, the group will anchor several two-foot-long rockets in the sand, tethered to a 60-the beach, poker-faced, and unobtrusively try to nudge the suspicious birds toward the net. This usually takes at least an hour, barring any startling interruptions from low-flying aircraft or rock-throwing youngsters.
"You have to look like you are not at all interested in them," says Linda Leddy, a veteran know nabber and Manomet biologist, referring to how easily the birds get spooked.
"It's like trying to push a jellyfish," adds Harrington, who has been studying the birds for at least eight years. "You push the back side and then you have to wait for the front to respond."
when the birds are finally elbowed into range, someone will fire the rockets, flinging the net out some 60 feet. Startled, few of the birds are generally able to escape in the couple of second it takes the mesh t settle. "With luck, we might catch 500 to 600 at a shot," Harrington says.
Nabbing the birds hasn't always been so easy. In the past few years the researchers have experimented with a variety of tried-and-not-so-true methods.One involved setting small snares of fish line in the birds' path along the shore. No good. It often took three hours to catch one bird.
Another was to run a wire fence along the shore, one end of it stretching toward a cloverleaf-shaped trap. The idea was the birds would follow the fence into the snare and be unable to get out. No good, either. The birds balked just before entering the trap. Still a third involveed sneaking up on the birds at night, blinding them with a flashlight, and then grabbing them barehanded -- a practice successfully used by hunters in the late 1800s. this proved to be for the birds, too. It was abandoned without a know caught.
So, rocket-launched nets it is -- if, that is, the bird researchers are able to soothe any jitters the Argentina government may have about their entering the country with the fireworks.
Once capture, the birds will be gently stuffed into juice cans and weighed on a balance scale.They also will be measured and marked on their underbellies with yellow dye. The harmless coloring will stay on only until the next time the birds molt. Small colored flags and aluminum bands (their "social security numbers," Harrington says) will be clamped to each bird's leg. All the vital statistics will be recorded on cards that look like bowling scorecards, only smaller.
Bird "spotters" will then be on the lookout for the markings. In the past six years, members of the Manomet observatory, together with the Canadian Wildlife Service, have organized a network of bird-watchers up and down the red knots' flyway in 19 countries and commonwealths. It includes everyone from barbers to bankers.
So far, the researchers have marked more than 2,000 knots, tagging them everywhere from the bleaches of James Bay to the coasts of Massachusetts, Ner Jersey, and Florida. Spotters report seeing abut 200 marked birds each year.
For all the stealthful stalking, the bird-nabbing, it must be remembered, is being carried out in the name of science. By studying birds. Manomet researchers point out, man can learn more about his environment as well as another fascinating form of life.
"There is more to life on earth than humans," Linda Leddy points out. To perpetuate bird life, she says, people first have to understand them better.
"It [the bird world] is extraordinary -- full of magnificent forms and shapes and motion," adds David Twitchell, a Manomet trustee who will be going along on the trip. "If you ask the average 'birder' why he looks at birds, there will be as many answers as there are people. Some would say it's music, art -- this is one more form of it."
Yes, but all the way to the other side of the world for a performance?
"It is going to be fun in a rustic kind of way," John Hubbard, an engineer and Manomet trustees, says. "We're traveling to a place where none of us would ever normally choose of go."