Waders—The World’s Greatest Wanderers
BY AWAKE! WRITER IN SPAIN
IMAGINE spending two months of the northern summer in the Arctic tundra, where the sun practically never sets. As winter approaches, though, you head to South America, Australia, or South Africa. And for the rest of the year, you are on the move, combing the shores of every continent for your favorite delicacies. This is the typical lifestyle of many of the world’s waders.
Waders—as the name implies—are birds that like to feed in shallow water. * In the colder months of the Northern Hemisphere, these shorebirds congregate at muddy estuaries, beaches, mudflats, or rocky shorelines, where few humans care to wander. In the warmer months, when tourists flock to the beaches, most waders migrate to Arctic and subarctic regions, where the brief summer provides them with the solitude and abundant food they need for rearing their young.
Waders do not have especially vivid colors, but their dashing flight and striking wing markings capture the admiration of countless observers. “[Shorebirds] may fly with their wingtips grazing the water or at altitudes of four miles [6 km] or more. They are indeed absolute masters of the air and the wind,” notes the book Shorebirds—Beautiful Beachcombers.
Safety in Numbers
Shorebirds often congregate in large flocks where food is plentiful. They seem to seek safety in numbers. Birds of prey such as peregrine falcons prefer to pursue solitary birds, whereas a compact flock may discourage them from attacking. And thousands of watchful eyes make it more likely that a predator will be spotted in time. To benefit from this extra protection, many waders form mixed flocks of several species.
When a flock of shorebirds takes to the air, it is a sight to behold. Hundreds or even thousands of tightly packed birds twist and turn, rise and fall, as if some invisible hand were controlling them all. “That thousands of birds flying together at high speeds are able to execute abrupt manoeuvres with precise co-ordination is a miracle in itself,” states the Handbook of the Birds of the World. By studying high-speed film of flocks of dunlins, ornithologists have concluded that a single bird may initiate a maneuver that quickly spreads to the rest of the flock.
The World at Their Feet
Some waders are truly global travelers. Red knots and sanderlings, for example, breed farther north than virtually any other birds. Waders may turn up on shorelines practically anywhere on earth and may cover some 20,000 miles [32,000 kilometers] in their annual odyssey.
Although some migratory journeys require waders to cross oceans, they cannot swim and never rest on the water. So they must carry huge reserves of fuel—proportionately more than a jumbo jet does, which on takeoff carries about 40 percent of its total weight in fuel. How do the waders fuel up?
“They accumulate [fuel] in the form of fat and feed so voraciously on the mud flats of the coast that in a few weeks they almost double their summer weight,” explains David Attenborough in the book The Life of Birds. “These reserves are even bigger than that statistic might suggest, for many of their internal organs, including their brain and their guts, shrink in size to accommodate this additional fuel and save weight.”
One impressive traveler is the Pacific golden plover, which migrates from Alaska to the Hawaiian Islands. Apart from the endurance needed for the 2,800-mile [4,500 km] direct flight, its ability to locate Hawaii in the middle of the ocean is a miracle of avian navigation. A golden plover whose flight was monitored made the journey in less than four days. And one elderly bird has completed the round trip over 20 times!
When they finally begin arriving in their Arctic breeding grounds, these hardy travelers face a hectic life. Within two weeks they must find a mate, establish a territory, and make a nest. They then have about three weeks to incubate the eggs and another three weeks to rear their chicks. By the end of July, they are heading south once more.
The Hazards of Migration
On the long journeys that shorebirds undertake, they encounter many hazards. One great threat comes from humans. In the 19th century, naturalist John James Audubon reported that a hunting party shot 48,000 American golden plovers in a single day. Today, the total world population of this species has recovered somewhat, but it is still probably less than the number killed that day.
An even greater threat to waders is the disappearance of wetlands. Shorebirds cannot easily adapt to such losses. “The patterns of breeding, migration and wintering distributions of waders have been built up over many thousands of years and it is all too easy for man to change or destroy them,” explains the book Shorebirds—An Identification Guide to the Waders of the World. The survival of millions of waders depends on the preservation of a handful of key migratory stopovers.
A prime example is Delaware Bay, along the coast of southwest New Jersey, U.S.A. There, about a hundred thousand red knots congregate in spring to gorge on the eggs of horseshoe crabs. The birds are ravenous, since they have just completed “one of the longest non-stop flights of the avian world.” In two weeks they have flown 5,000 miles [8,000 kilometers] to this location from southeastern Brazil, during which time they have lost half their body weight.
Efforts of conservationists may help to ensure that such favorite stopovers of the shorebirds will remain intact. Perhaps there is one such area not far from where you live. Once you have watched a flock of waders twisting and wheeling over the waves or you have listened to their haunting calls, you will find it hard to forget them.
As naturalist Arthur Morris writes, “all who pursue shorebirds share a common bond: each of us has stood countless times on desolate beaches or flats and watched a flock of sandpipers flashing dark and light, twisting and turning in synchronous flight. And each time this happens, we are filled with a sense of awe and wonder.”
^ par. 4 Waders, or shorebirds, belong to the scientific order Charadrii and number over 200 species.
[Box/Pictures on page 18]
Red knots probably earn the prize for long-haul travel. Those that breed in the far north of Canada usually winter either in Western Europe or on the tip of South America (over 6,000 miles [10,000 km] away)
Flocks of almost a million dunlins have been observed in the Netherlands and Mauretania
Bar-tailed godwits disperse widely from their breeding grounds in Siberia, traveling to the British Isles, South Africa, the Middle East, Australia, or New Zealand
Sanderlings can be found running along beaches practically anywhere in the world. Some may breed within 600 miles [950 km] of the North Pole
[Pictures on page 16, 17]
To cross vast oceans, waders must acquire huge reserves of fat, since they cannot rest on water
[Picture on page 16, 17]
Sanderlings seek safety in numbers
[Picture on page 17]
[Picture on page 17]
A spotted redshank searches for food in the marshes
[Picture Credit Line on page 16]
Top and bottom panoramic photos: © Richard Crossley/VIREO