Longest Migratory Flights
Arctic tern (Sterna paradisaea)
Recoveries and at-sea surveys suggest that despite Arctic tern’s small size (4-ounce or 113-gram), its annual migration from boreal and high Arctic breeding grounds to the Southern Ocean may be the longest seasonal movement of any living creature, about two times farther than previously thought, a new study says. Tracking of 11 Arctic terns fitted with geolocators (weighing 1.4 grams, light enough for an Arctic tern to carry on a band around its leg) revealed the birds do indeed travel huge distances (more than 80,000 km annually for some individuals).
It has now been discovered that Arctic terns follow zigzagging routes between Greenland and Antarctica each year. In the process, it racks up about 44,000 frequent flier miles (71,000 kilometers)—edging out its archrival, the sooty shearwater, by roughly 4,000 miles (6,440 kilometers).
On their spring trips back to Greenland they again follow a zigzagging route. Rather than flying straight up the middle of the Atlantic, the birds hopscotch from Antarctica to Africa to South America to the Arctic.
But there’s a method to their madness.
“It’s a detour of several thousand kilometers,” said the lead author of the study, Carsten Egevang of the Greenland Institute of Natural Resources. “But when you analyze it, it makes perfect sense.” Findings published in the journal Proceedings of the National Academy of Sciences.
The birds appear to be following huge spiraling wind patterns in the atmosphere, avoiding flying into the wind, he said.
“There have been all kinds of theories, but now, for the first time, we’ve been able to show what the birds are doing out there,” said Egevang.
Since the birds often live 30 years or more, the researchers estimate that, over its lifetime, an arctic tern migrates about 1.5 million miles (2.4 million kilometers)—equal to three trips to the moon and back.
Study found the birds often stop for a month in the open North Atlantic Ocean, probably to “fuel up” on fish and small crustaceans before setting off to cross the tropics.
Regardless of the route, no one’s sure why arctic terns have such a long migration in the first place. “My gut feeling,” Egevang said, “is that it’s because of the rich [polar] feeding grounds that they travel so far.”
These graceful birds that are about 38 cm long breed within 730 km of the North Pole, i.e. the arctic coasts of Alaska, Greenland, Canada, Europe and Siberia during the short and virtually nightless arctic summers and winters on the Antarctic ice edge. In other words they breed near the North Pole. As winter approaches in the northern hemisphere they migrate to South Pole and come back in summers again.
Few years back when the technology was not so advanced as it is today, the greatest distance recorded was 18,056 km, one side, (11,222 miles) covered by a bird, ringed (No. CK51037), at Valley, Anglesey, North Wales on 26 or 28 June 1966 and recovered near Bega, New South Wales on 31 December 1966.
The greatest of all avian migrants, arctic terns remain on wings for eight long months during its journey from breeding grounds to wintering grounds and back.
Enjoys most daylight in the world
Arctic tern is remarkable in one more aspect. It enjoys more daylight and least night-time than any other creature on earth, while journeying from one polar summer to other. The summer of the high arctic is very short with daylight almost throughout the twenty-four hours and this bird breeds as far north as 82 degrees. It raises its young in the short-lived summer when there is abundance of insects and fish in the north, and while wintering in the south Antarctic Ocean it enjoys almost perpetual daylight and an immensely rich food supply of small fish and planktons.
It has many enemies, especially the larger gulls, skuas and other predators. In colonies its eggs and young suffer severe losses – usually only about 16 per cent of the offspring reach maturity.
Great Snipe (Gallinago media)
Available data shows that Great Snipe is not only a long-distance migrant, but more astonishing is the fact that it covers the entire distance at a great speed. As of today there is no known animal that covers such vast distances at such a great speeds.
In 2011 Swedish scientists who tracked the great snipe from Sweden to central Africa, using tiny tracking devices called geolocators, found that the bird flies non-stop over a distance of around 6,760 km (4,200 miles) at a speed of 97 km/hr (60 mph). They say there may be other birds that are quicker, but are yet to be accurately tracked.
There are lot of birds that can fly either very far or very fast, but the great snipe does both. For instance, peregrine falcon, considered the fastest bird on the planet, reaches an astounding 400 k/h (249 mph), but only while diving to catch its prey. And the Arctic tern flies farther than any other bird during its migration – around 80,500 km (50,000 miles) from the Arctic to the Antarctic and back again. Although it’s an incredible feat for such a small bird, but it doesn’t fly at great speed.
In a report published by the scientists in May 2011 in the Royal Society journal Biology Letters, they wrote: We know of no other animal that travels this rapidly over such a long distance.
What’s also unusual is that its migration route takes it over land that is perfectly suitable for a stopover. Dr. Raymond Klaassen from Lund University in Sweden, lead author of the study, said: “We never expected record-breaking flights for this ordinary bird. Along its routes, the snipes have plenty of opportunity to stop over and feed on earthworms, insects and other invertebrates, and this is exactly what land birds normally do.”
Migratory birds almost always choose to stop over during their migrations if they can, at a place where they can rest and refuel before continuing their epic journeys. For example, Arctic terns, when flying over the Atlantic, feed on surface fish, while the bar-tailed godwit flies from Alaska to New Zealand with no stopover, “because it has no choice,” says Klaassen.
For the purpose of tracking the researchers fitted 10 male great snipes at Jämtland in Sweden with a geolocator each. Exactly a year later, the scientists managed to retrieve three geolocators from three birds when they returned to Sweden after their northward migration.
Klaassen and his colleagues found that one bird flew 6,800 km (4,225 miles) from Sweden to central Africa in just 3.5 days. The other two birds flew 6,169 km (3,833 miles) in three days, and 4,619 km (2,870 miles) in two days.
Great snipes breed in Scandinavia from mid-May to early July. The birds leave their breeding ground from early August onwards. The return migration happens between March and April.
Sooty shearwaters (Ardenna grisea)
Sooty shearwaters are spectacular long-distance migrants, but they do not migrate as a flock, rather as single individuals, associating only opportunistically. In the Atlantic Ocean, they cover distances exceeding 14,000 km (8,700 mi) from their breeding colony on the Falkland Islands (52°S 60°W) north to 60 to 70°N in the North Atlantic Ocean off north Norway; distances covered in the Pacific are similar or larger; although the Pacific Ocean colonies are not quite so far south, at 35 to 50°S off New Zealand, and moving north to the Aleutian Islands, the longitudinal width of the ocean makes longer migrations necessary. Recent tagging experiments have revealed that birds breeding in New Zealand may travel 74,000 km in a year, reaching Japan, Alaska and California, averaging more than 500km per day.
During migration they follow a circular route, traveling north up the western side of the Pacific and Atlantic Oceans at the end of the nesting season in March–May, reaching subarctic waters in June–July where they cross from west to east, then returning south down the eastern side of the oceans in September–October, reaching to the breeding colonies in November.
In Great Britain, they move south in late August and September; with strong north and north-west winds, they may occasionally become “trapped” in the shallow, largely enclosed North Sea and heavy passages may be seen flying back north up the British east coast as they re-trace their steps back to the Atlantic over northern Scotland.
These birds breed on small islands in the south Pacific and south Atlantic Oceans, mainly around Tierra del Fuego, New Zealand, Falkland Islands and also in the Phillip Island off Norfolk Islands and Auckland Islands. Their breeding starts in October; incubation period is of about 54 days. Once the chicks hatch they remain with their parents for 86 to 109 days.
Northern wheatear (Oenanthe oenanthe)
Its a tiny songbird weighing just 25 grams, migrates from the Arctic to Africa and back every year, covering a distance of up to 29,000 km. A study appeared (February 2012) in the journal Royal Society of Letters has claimed.
“Scaled for body size, this is one of the longest round-trip migratory journeys of any bird in the world and raises questions about how a bird of this size is able to successfully undertake such physically demanding journeys twice a year, particularly for inexperienced juveniles migrating on their own,” says Ryan Norris of the University of Guelph in Ontario, Canada.
Birds with larger wingspans such as the cuckoo and albatross are famous for their transcontinental migrations, but this study provides incontrovertible evidence that a songbird, smaller than a robin but a little larger than a finch, can do the same, say the scientists. “They are incredible migratory journeys, particularly for a bird this size,” says Ryan.
Biologists who tagged the tawny-and-white insectivore were stunned at its flight endurance. They attached minute geolocators, each weighing just 1.2 grams to the legs of 46 wheatears in Alaska and on Baffin Island in northeastern Canada.
Birds released in Alaska spent the winter in Africa before returning back home, a journey of about 14,500 km each way, in which they flew on average 290 km a day.
They traveled over Siberia and across the Arabian desert, heading to Sudan, Uganda and Kenya, a trip that took about 91 days on the outward trip but 55 days for the return leg.
A tagged bird from Baffin Island flew over the North Atlantic, landed in Britain, travelled southwards across continental Europe, the Mediterranean and Sahara to winter on the coast of Mauritania, West Africa, taking 26 days out and 55 days back for a trip of about 7500 km.
Rufous hummingbird (Selasphorus rufus)
This 8 cm (3.1 in) long bird that weighs only 3-4 grams is known for its extraordinary flight skills. It covers 3,200 km (2,000 mi) during its migratory transits, which is the longest migratory journey of any hummingbird.
During spring migration, it travels from Mexico to Alaska. The bird begins its migration from the wintering grounds as early as January. Traveling along the Pacific Coast, they reach the northernmost point of the breeding range in Alaska by mid-May.
These birds are well adapted to cold temperature, which allows them to migrate into areas where night time temperatures in early spring may drop below freezing. They are capable of surviving sudden cold and snows typical in springtime. For this they routinely go into torpor at night, probably because it may freeze at night even in July in their nesting grounds in Canada and Alaska.
Rufous Hummingbirds make a clockwise circuit of western North America each year during this long migration. They move up the Pacific Coast in late winter and spring, reaching Washington and British Columbia by May. As early as July they may start south again, traveling down the chain of the Rocky Mountains.
They breed as far north as southeastern Alaska – the northernmost breeding range of any hummingbird on earth. Of the western hummingbirds that occasionally show up in the east, the Rufous Hummingbird is the most frequent.
Ruby-throat hummer (Archilochus colubris)
This 7 to 9 cm long migratory bird with an average weight of 3-4 grams spends most of the winter in southern Mexico and Central America, as far south as extreme western Panama, the West Indies and southern Florida. During migration some birds embark on a 20 hours nonstop journey of 845 km (525 mi) across the Gulf of Mexico. They go further up to another 1,600 km (1,000 mi) into Central America.
Before departing, each bird almost doubles its weight, from about 3 grams to over 6 grams, by overeating; when it lands at the U.S. Gulf coast, it may weigh 2.5 grams. These birds have a heart-beat rate of about 250 times per minute while resting, while flying it goes up to 1,220 beats per minute.
Ruby-throated hummingbird that nests in Canada must also fly from there to the Gulf Coast, a distance of another 1,600 km (1,000 mi) or so. Some birds that are not fully fit or strong skirt direct flight across the Gulf of Mexico and go overland through Mexico or short-cut the Gulf flight by flying from the Texas coast into Mexico.
They breed throughout most of eastern North America and the Canadian prairies. The female builds a nest in a protected location in a shrub or a tree. Of all hummingbirds in the U.S., this species has the largest breeding range.
American golden plover (Pluvialis dominica)
A medium-sized plover is known for the longest uninterrupted flights. It has one of the longest known migratory routes of over 40,000 km (25,000 mi). Of this, 3,900 km (2,400 mi) is over open ocean where it cannot stop to feed, drink or take rest. During this period it sustains itself from body fat store that it stocks up on prior to the flight.
These birds have a long, circular migration route. In autumn they fly offshore from the East Coast of North America nonstop to South America. In the spring when they return they pass primarily through the middle of North America to reach their Arctic breeding grounds.
Interestingly, adult birds leave their breeding grounds in early summer, but juveniles usually linger until late summer or autumn. Some adults arrive on the wintering grounds in southern South America before the last juveniles have left the Arctic.
A comparison of dates and migratory patterns has lead experts to conclude that Eskimo curlews and American golden plovers were the most likely shore birds to have attracted the attention of Christopher Columbus to nearby America in early October 1492, after 65 days at sea out of sight of land.
Non-stop flights are common among migratory shorebirds (also known as waders) and often involve trans-oceanic crossings. Besides, American golden plovers there are other examples also of non-stop long distance flying birds that include Ruddy turnstones (Arenaria interpres) flying 4,000 km between the Pribilof Islands and Hawaii, and Red knots (Calidris canutus) flying 4,800 km between the Wadden Sea and their breeding area on Taymyr.
Bristle-thighed curlew (Numenius tahitiensis)
A medium-sized shorebird that breeds in a few hilly areas of western Alaska and winters on tropical Pacific islands. Its first leg of the migration includes a nonstop 4,000 km flight from Alaska to Laysan. It can make non-stop flights in excess of 6,000 km.
Studies on Laysan Island showed that birds wintering in the Central and South Pacific overfly the Northwestern chain during spring and fall migration, making nonstop flights in excess of 6,000 km twice each year. Thus, Bristle-thighed Curlews along with Bar-tailed Godwits (Limosa lapponica), make one of the longest nonstop flights known for any bird.
Adult birds leave their chicks at about five weeks of age to undertake their southward journey. Chicks continue to feed until they are able to make the journey.
In its biology and behavior, the Bristle-thighed Curlew is one of the most unusual of all shorebirds. It’s the only species of migratory shorebird that spends nonbreeding season entirely in Oceania, over an area stretching from the Hawaiian Archipelago south to the Pitcairn Islands and from the Marquesas Islands west to the Marshall Islands. To reach the nearest site in this vast area, birds from Alaska must cross at least 4,000 km (and up 10,000 km) of open ocean. Like a handful of other species, they also take on huge fat stores to fuel long nonstop flights over open ocean and reduces the size of its nutritional organs in preparation for these flights.