SEABIRDS

SEABIRDS

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Arctic terns
The Arctic tern has the longest migration of any bird. Every years it flies up to 25,000 miles between the Arctic and the Antarctic and back, with much of the flying done over water. It nests on the Arctic region. When the young are old enough to fly the whole family flies south to Antarctica. The tern’s wings are long and powerful and they can make steady headway even against strong headwinds.

Arctic terns begin their journeys southward in August, Those that winter in Arctic Canada and Greenland fly across the Atlantic and meet those that have flown south from the Russia Arctic. Some fly to the Cape of Good Hope Hop via West Africa. Others across the Atlantic again to the east coast of South America to the Cape Horn. A third group follows the Pacific coast from Alaska to Chile. All three groups fly to Antarctica. In February they begin flying back north. The total journey is a 25,000-mile round trip.

A bar-tailed godwith, a species of sea bird, was recorded flying 11,400 kilometers from Alaska to New Zealand in 2008 with no rest or food. The red knot is a sandpiper-like bird that flies 15,000 kilometers between Tierra del Fuego and the Arctic. Critical to their trip is a stopover in Delaware Bay to feast on horseshoe crab eggs, The birds know when and where to find the eggs, in some cases doubling their weight after they feed on them. But these days horseshoe crabs and horseshoe crab eggs, which are taken by conch and eel fishermen as bait, are harder to find and a critical way station for the red knots is threatened.

Ian Poiner of Australia has tracked puffins that make a nearly 64,000-km circle every year from New Zealand to Japan, Russia, Alaska, Chile and back in what the census calls the “longest-ever electronically recorded migration.”

An estimated 300,000 seabirds are believed to be killed after being lured by baited hooks from long lines and then pulled underwater and drowned. The birds can be saved if the hooks are weight to drop them to depths the birds can not reach.

Tags placed on seabirds record levels of ambient lights that can be translated into longitude and latitude.

Bird Colonies

Many birds that spend a considerable amount of time at sea nest I huge colonies on isolated islands or remote cliffs or peninsulas. These birds nest together in crowded colonies not because sites are scare but rather because it easier for the birds to protect their young in packed conditions.

Gulls and other sea birds are threatened from the air by other birds and from the ground by animals like foxes. When an intruder shows up near a nesting site gulls rally together and harass the intruder until it leaves. Under similar circumstances an individual gull would have a hard time repelling the invader. Even under these condition only around 15 percent of eggs produce fledglings but this rate is higher than solitary nests where success rate in near zero.

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Bird colony in the Farne Islands Pinnacles

Shorebirds

Shorebirds are like their name says birds that hang out along the edge of oceans or other waterways, generally on mud flats or sandy beaches. Many are waders that have long legs for wading and long bills for picking out and probing prey. Some species have sensory nerve ending at the end of their bills that help them locate prey in the mud or sand. Their wings are built for fast quick getaways rather than gliding and soaring.

Waders and shorebirds include plovers, snipes and sandpipers. These birds feed on tiny creatures such as crabs, worms and shrimps in shallow water found around the shores of oceans, lakes and rivers. Some have long bills for poking deep in the mud. Others snatch prey on the surface.

Shorebirds are primarily birds of ocean coasts, especially adapted to feeding on tidal flats and marshes, which abound in the small invertebrates they thrive on. At this time of year, however, the newly planted rice paddies, filled with shallow water clear enough to see the bottom, look and function much like tidal flats.

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Shorebirds like to work the edges of waves. They don’t mind getting their feet wet but not their bodies. They often work the beaches in flocks. Some members are always on the lookout for predators. They are often busiest at low tide, when the beach stretches out the furthest. Shorebirds extract large quantities of small mollusks from sandbanks and mud flats when the tide retreats. The animals are extracted from the shells with a flick of the head.

Many shorebirds don’t make nests. They rely on the camouflage coloring of their eggs. Some shorebirds that nest in cliffs lay eggs that are pointed at one so they roll in a circle rather than rolling off the cliff.

Many species of shorebird migrate. Protecting them is difficult because their wintering grounds, breeding grounds and stopover points are all like links in a chain and if one of them fails the whole chain can fall apart.

One of the largest shorebirds is the whimbrel. This is a cosmopolitan species that migrates up and down both sides of the Pacific and Atlantic seaboards. The long bill is down-curved near the tip, ideal for probing deep into mud and even poking down into crab burrows, which are usually dug on a curve. The tip of the bill is fitted with sensitive nerve endings that allow the whimbrel to feel prey that they can't even see.

Sandpipers and Plovers

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Snowy plover
Sandpipers and plovers are generally referred to as "shorebirds" in North America and "waders" in Britain. About 200 species have been identified worldwide. [Source: Kevin Short, Daily Yomiuri, May 19, 2011]

One of the largest shorebirds is the whimbrel. This is a cosmopolitan species that migrates up and down both sides of the Pacific and Atlantic seaboards. The long bill is down-curved near the tip, ideal for probing deep into mud and even poking down into crab burrows, which are usually dug on a curve. The tip of the bill is fitted with sensitive nerve endings that allow the whimbrel to feel prey that they can't even see.

The ruddy turnstone is a smaller sandpiper with a short, thick bill that flips slightly upward at the tip. These birds, called simply turnstone in Europe and Asia, often search for prey by flipping over stones, leaves and other small objects. Their bill, however, is also well suited to probing in shallow mud. Gray-tailed tattler are medium-size sandpipers with medium-length straight bills. They feed in a probing manner similar to that of the whimbrel, but can be easily identified by their bright yellow legs.

Plovers in general have shorter bills than sandpipers, and locate their prey visually rather than by probing. The pacific golden plover is a thick-bodied, powerful bird. At this time of year some individuals still retain their drab winter plumage, but others have already molted into magnificent black, gold and white feathers.

These migratory shorebirds only stay a short fortnight here in the Japanese countryside, but the local rice paddies play a vital role in their conservation. All four of them spend their winter months along the coasts of Australia and Melanesia. Their summer breeding grounds, however, are on the tundras of Siberia and even Alaska. Japan is ideally positioned as a stop-over and resting stage on the long journey northward. During their brief stay here the shorebirds rely on the abundance of the rice paddies to replenish their depleted fat and energy reserves.

Avocets, Oystercatchers and Sanderlings

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Pied oystercatcher
Avocets are shorebirds with a characteristic upturned bill. When a member or a pair return to take over incubation duties, the birds exchange a series of "cwit, cwit, cwit" sounds and throw straw at one another.

Oystercatcher feed on oysters as their name suggests and other bivalve molluscs such as clams and mussels. Opening a shell for a bird is no easy tasks. Some do it by prying open the shell and cutting the muscle that holds them together (a method called “stabbing”). Other pick holes into shell with their bills and break the shells apart (a method called “hammering”).

Sanderlings are the small, plump birds that race back and forth on the shoreline, just in front of incoming waves. They are extremely fleet foot for birds. They hang out in small flocks and snatch small crustaceans and insects in the sand. "As each wave swills back, they follow it, probing and pecking at any morsel that has become stranded and then as next wavelet floods in, they run back again to the shore." They often fight among themselves. If they are disturbed they make a "twick, twick" noises and quickly fly out over the sea until the threat is gone.

Sanderlings are found on beaches all over the world. They are very tame and people can get quite close to them before they fly off. They migrate between southern areas in the winter and northern areas in the summer. Sanderlings belong to the same family of bird as sandpipers. The two families of birds are often found together. Sanderlings can be distinguished by their larger size and whiter appearance in the autumn.

Gulls

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Arctic tern
Gulls and terns are mostly sea birds.. They have webbed feet and are good swimmers. Diverse and adaptive, gulls eats almost every thing: worms, crustaceans, chicks, other gull’s chicks, grain crops, dead seals, garbage. They also have large mouths and throats and have been observed eating entire large starfishs in one bite. In 1829, a naturalist clubbed one gull on the head. The bird then proceeded to discourage an entire auk — a foot-long seabird now extinct. An autopsy revealed another auk in its stomach. Gulls are among the few birds that can easily snatch thrown food out of the air.

Gulls are incredibly diverse and adaptive birds, always ready to take advantage of any source of easy food. They push in with the pigeons and pintails whenever someone scatters a handful of potato chips or some other unhealthy snack. Experienced gull feeders, however, simply throw their fare high into the air. The gulls are the only birds capable of snaring a cheese doodle in midair. [Source: Kevin Short, Daily Yomiuri, February 5, 2007]

Fully adult black-headed gulls have deep orange bills and feet, and completely white tails. Mixed in with these, however, are younger birds experiencing their first winter. These have paler (almost yellow) bills and feet, and also a thin black band at the tip of their tails. Many species of gull take several years to mature into breeding adults.

Terns and Skuas

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Arctic tern chick
Terns are smaller than gulls and have wings and feet that are designed for flying. They tend to be plunge divers capable of diving deeper in the water than gulls. Terns primarily eat small fish they catch by diving into the surface of the sea. A male courting a female, brings her one or two fish, carrying them crossways in her bill.

Noddy terns are noted for their tameness. Arctic terns are known for their long migrations (See Above). Sooty terns take flight when the leave their nests and don’t land or settle on land until it nests three or four years later.

Skuas are gull-like birds with a nasty reputation. They scavage around bird colonies, taking eggs and chicks and forcing older birds to discouraged their meals.. They are strong and act like raptors.

The downy chicks of gulls and terns are almost invisible crouching in the brush. When an intruder approaches, the adult flies off and leaves the chicks alone. The chicks don't move regardless of how close the predator approaches.

Gulls form same sex partnerships when they can not find opposite sex partners. Up to 15 percent of Western gull pairs are females, who build joint nests and take turns watching over unfertilized eggs and woo each other with gifts of food. Sometimes one member will mate with a male but the female pair will raise the young.

Gannets and Boobies

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Gannets and boobies are sea birds famous for their extraordinary diving ability. Feeding alone or in flocks, the dive like missiles from great heights to capture fish and squid. Sometimes gannets will pursue their prey underwater, moving with half open wings and powerful feet. Boobies are known for chasing other boobies until they regurgitate their meal and then stealing it.

Gannets are huge birds. They have eight-foot wingspans and usually nest offshore. Gannet fledglings stand on the edge of the cliffs, flapping their wings and strengthening their muscles before they try to fly.

Gannets are fiercely territorial nesters. They fortify their nests with seaweed and bird droppings and squawk and scream loudly whenever other birds approach too close. In New Zealand the chicks are usually born in October and fed regurgitated squid and mullet by their parents over the next six months. In April and May, the young gannets learn to fly and fly off to 1,500 miles across the Tasman Sea to Australia (many die in the process). After three years the survivors return to give birth to their own young and spend the rest of their life in New Zealand.

The Galapagos islands is home to blue footed boobies, red footed boobies and masked boobies. Boobies protect their eggs under their webbed feet. Only one of the two hatchling is feed and thus survives.

Red footed boobies are said to be so dumb they some sometimes fly right into the masts of ships, but recover with "amazing agility" according to one observer. When a pair of blue footed boobies go through the mating ritual, the female rocks back and forth like Charlie Chaplin and the male looks, spreads his wings and whistles.♂

Frigate Birds

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Male greater frigate bird displaying
Frigate birds have a wings span of seven feet and are very maneuverable but they are known best of enormous red pouches that males have under their bills which they inflate during their courting ritual. Unlike most other ocean going birds frigate birds can't dive which partly explain why they often harass other birds — usually boobies — and make them drop their catch which the frigate birds scoop up in mid flight.

In the Galapagos Islands frigate birds put on the their courtship display during the first six months of the year. After a male has found what he thinks is a good nesting site he inflates his gular sacs which expand like brilliant red heart-shape balloon. When he spots a cruising female he flaps his wings, shakes his head and bellows like a rutting elephant.

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Male frigate bird
After a male successfully woes a female the two of them build a nest together and take turns guarding the egg during the eight week incubation period. After the chick is born the parents must maintain a vigil against cannibalistic frigate birds and short eared owls for five months until the young birds can fly.

Shearwaters and Petrels

Shearwaters and petrels belong to a group called tubenises. They are the most widely distributed of all bird species, ranging from 250 kilometers inland in the Antarctic to the nearest pieces of land to the North Pole.

Shearwaters and petrels are a large family of birds. They are divided into four groups: 1) fulmars (cold water birds found mostly in the southern hemisphere); 2) prions (southern hemisphere birds, smaller in size than fulmars; 3) gadfly petrels (a group with 30 or species that nest underground in large colonies); 4) true shearwaters (a group with 23 species that have long, thin bills adapted for catching fish and zooplankton underwater).

Shearwaters and petrels spend much of their time flying over the open sea feeding on whatever they can get their beaks on. Shearwaters get their name from the habit of many species of skimming along the surface of the sea when hunting.

Gadfly petrels have short, stout bill with a hook for gripping and a sharp edge for cutting up small squid and fish. Puffins and mutton birds are true shearwaters, which are highly social birds, that sometimes from dense feeding rafts in the middle of the sea.

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Short-tailed shearwater
Storm petrels and diving petrels are separate families birds. They too nest in burrows and form colonies. Some species of storm petrel have long legs they use to bounce or “walk” on the water while feeding. Some species migrate long distances Diving petrels have short, stubby wings that are ideal for flying in the air and in the water. They are known for their ability to dive deep in the water, staying submerged for considerable periods of time, as they pursue fish.

Sooty shearwaters have been recorded flying 40,000 miles around the Pacific Ocean in a year, the longest electronically-recorded animal migration. Scientist have tracked 19 of the birds from breeding colonies New Zealand. These shearwaters fly east from New Zealand then north to wintering areas, some flew to waters off Japan, others to the Alaska and California, places where food such as krill is abundant..

Shearwaters tagged by the Census of Marine Life’s Tagging of Pacific Predators (TOPP) project off New Zealand made a 262-day, 39,790-mile round-trip journey in a figure-eight pattern, the longest animal migration ever recorded electronically at the time.

Expert: Paul Scofield, of New Zealand’s Canterbury Museum and co-author of “Albatrosses, Petrels and Shearwaters of the World”.

Shearwaters and Petrel Senses

Shearwaters and petrel nostrils are protected by a pair of tubes which extend down the beak and allow them to smell better than other birds. It is not quite clear what they use their sense of smell for. They hunt at sea where smell is not much of an advantage. Maybe smell helps them locate their hole in their crowded colonies.

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Audobon's Shearwater
Shearwaters have extraordinary navigation abilities. In a famous case, a shearwater was taken from the island of Stockholm in west Wales by plane to Boston, 5,100 kilometers way and released. It found its way back to its burrow 12½ days later. It is not known how it found its way back.

Petrels and some other sea birds have nostrils that excrete excess salt. Once thought to be airspeed indicators, the nostrils are a long, horny tubes perched above the beak. Salt fluids from glands above the eyes pass through the nostril and drip off the bill.

Shearwaters and Petrel and Their Young

Many shearwaters and petrels live on remote islands or remote locations where predators are not present. Most lay their eggs in burrows. Many establish huge colonies. True shearwaters mostly visit their burrows at night.

Shearwaters and petrels lay their eggs and brood their young in holes. During the day their breeding areas are quiet places as they adults are either at sea feeding or in their holes with their eggs or chicks, which offer some protection from the skuas and gulls that harass them.

Shearwater and petrel adults extract oil from the sea creatures they eat and regurgitate in the mouths of their young. They also squirt oil at intruders. The oil often gets all over the place. This combined with the smell of the birds themselves makes their colonies very smelly places.

Pelicans

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Brown pelican
Pelicans are water birds with long bills and extendable pouches with a capacity of 12 liters. They weigh up to eight kilograms, making them among the largest flying birds, and have an awkward, ungainly appearance and have been described as feathered basset hounds. Pelicans are remarkably adapted for their water environment. They have air sacs under their skin that give them remarkable buoyancy and help stay upright in even the waviest conditions. [Source: Mel White, National Geographic, June 2006]

There are seven species of pelican. They have existed more or less in their present form for at least 20 million years. Pelicans tend to stay close to the shore rather than venture out into to the open ocean. Most pelicans nest and feed near fresh water and can feed in both fresh and sea water. The brown pelican is the only true marine pelican. It is the only one that dives for food. They others mostly sit on the surface and dip their bills into the water to feed.

Pelican tend to live no longer than 20 years. Some pelicans have a nine foot wingspan, which is more suited more for soaring and gliding and picking up air currents than flapping, and gives them remarkable endurance and grace in the air. Many pelicans migrate between summer nesting areas and wintering areas to the south. They often fly in a V formation. Like bicycle riders, these birds use less energy if they follow in the slip stream of a bird front of them. As the group flies forward the bird at the front gets tired and goes the back and is replaced by another leader.

During the mating seasons both males and females of some species grow nobs on their bills. Adults are virtually voiceless. This means that their mating overtures are based on body language rather than calls. They express their desire by turning red in the face. Both males and females tend the nest and take care of incubating the eggs.

Pelican Feeding

Brown pelicans, the only true marine pelican and the only one that dives for food, catch fish by folding their wings in flight and plunging ito the water at speeds up to 40 mph. Other pelicans such as the American white pelican float in large flocks and work co-operatively to herd schools of small fish into areas such as shallow water coves where the fish can be encircled like a net and scooped up by the pelicns with their pouch-like bills in a flurry of thrusting and swimming.

Many pelicans live in large flocks and work together to catch fish. They form squadrons of several dozen birds. Sometimes they form a ring and all dips their heads in the water at the same time. If a fish within the circle tries to get away it often will head straight towards one pelican in an effort to get away from another.

Brown pelicans are among the heaviest birds that catch fish by diving. David Attenborough, wrote in “The Life of Birds”, "They target individual fish, from thirty feet above the sea. Their dives are spectacular, as they draw back their wings, but they do not dive to a great depth. Their bodies are too big and buoyant, so though they hit the water with a considerable splash they cannot reach any fish, even with the tips of their long beak, that is more than thee feet down."

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In the words of a famous liberica by Dixon Merriit a pelican’s “bill will hold more than his “belly can.” "When they surface, their baggy bills are full of water as well as fish. To get rid of the water, as they must do before they swallow their catch, they have to open their bills slightly” and turn their necks. They then tip their heads back to swallow the fish whole. Some birds hang around pelicans and try to snatch fish out of the pelican’s mouth.

Pelican adults feed their young regurgitated fish or other creatures it catches. It takes about 70 kilograms of fish to raise one chick. Often pelicans travel more than 150 kilometers from their nests and back again to find food to feed their young.

Image Sources: Wikimedia Commons, National Oceanic and Atmospheric Administration (NOAA)

Text Sources: New York Times, Washington Post, Los Angeles Times, Times of London, Yomiuri Shimbun, The Guardian, National Geographic, The New Yorker, Time, Newsweek, Reuters, AP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.

Last updated January 2012


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