Albatross

Albatross

The albatross was the bird of ill omen, their repository of the souls of drowned sailors, and consequently to kill one was to court disaster. Yet paradoxically sailors were happy to catch and eat albatrosses to relieve the monotony of life and diet on long voyages. They must also have spent man-hours admiring the effortless flight of the albatrosses that followed their ships for hours with barely a wing heat. Adaptations for long-distance flight allow the albatrosses to exploit the vast spaces of the oceans from their restricted breeding bases on oceanic islands. The name albatross comes from the Portuguese Alcatraz, used originally for any large seabird and apparently derived from the Arabic al-carious, used for the pelican.

Albatrosses are typically associated with the belt of windswept ocean lying between the Antarctic and the southern extremities of America, Africa, and Australasia. The greatest number of individuals and species occurs between 45 and 70 degrees south. but they also breed in temperate waters of the southern hemisphere and a few species have spread into the North Pacific. The Waved albatross of the Galapagos and ‘Is lading la Plata off Ecuador breeds on the equator, but where the climate is under the influence of the cool Humboldt Current. Teller’s or the Short-tailed albatross (based on islands off Japan), the Black-footed albatross (of the northwest Pacific), and the Laysan albatross (from the Hawaiian archipelago) all breed in the North Pacific.  

Albatrosses are distinguished from others of their order (Procellariiformes) by the position of their tubular external nostrils, which lie at each side of the base of the bill rather That being fused on the top of the bill. They can be split into three convenient groups. the “great” albatrosses (three species .which have wingspans averaging 3m 1(about loft); nine smaller species which are often referred to as “molly auks” from the Dutch polemic which was originally given to the fulmar; and the all-dark Sooty and Light-mantled sooty albatrosses, having. relatively long wings and tails and which are sufficiently different to warrant a spear-ate genus.

From their habit of following ships. Albatrosses are best known as scavengers of offal thrown overboard. They have broad diets, including oceanic water striders and by-the-wind sailors (plankton) but a detailed analysis of diets shows that fish, squid, and crustaceans predominate. Prey is caught mainly by seizing at the surface, but occasionally by plunging in the manner of gang nets. They also feed during darkness, when many marine organisms come to the sure-face. The proportions of prey types differ between species and these profoundly affect the breeding biology of the species.

Albatrosses are long-lived, with an average lifespan of 3o years, but slow breeders. They are physiologically capable of breeding at three or four years but they do not usually start for several years after this. Some may not breed until 15 years old. When they first mature birds appear on the breeding grounds for a short while towards the end of the breeding season and thereafter spend more time ashore courting pro-specie mates. When a pair has been established they usually remain together until the death of one, and “divorce” occurs only after several breeding failures.

At the beginning of the breeding season, the male arrives at the colony first and mat-in occurs on the female’s reappearance. Most albatrosses nest in colonies, sometimes numbering thousands of pairs with close-packed nests, but Sooty and Long-mantled sooty albatrosses nest alone on cliff ledges. In several species, the nest is a pile of soil and vegetation that may be so large that the adults and difficulty climbing on. The tropical albatrosses make a scanty nest and the Waved albatross shuffles about with its egg on its feet.

The single egg is incubated in alternate shifts of several days by both parents, from about 65 days in the smaller species to 79 days in the Royal albatross. The newly hatched chick is brooded at first and later guarded. Throughout its life in the nest, it receives regular feeds from its parents. Once brooding has finished the adults remain ashore only long enough to identify their chicks and transfer a meal of undigested marine animals and lipid-rich oil derived from the digestion of prey.

Black-footed albatross chicks frequently wander up to 30 m from the nest and seek shade during the day, but they rush back when a parent arrives with food. Fledging takes from 120 days in Black-browed and Yellow-nosed albatrosses to 278 days in the Wandering albatross. The extremely long nesting period of the latter (356 days including incubation) means that it can attempt to breed only in alternate years since, after breeding; it must have a “rest” period during which it molts. At least six species are known to breed biennially. These include all the “great” albatrosses, the two sooty albatrosses, and the Gray-headed albatross along with the molly auks.

Breeding colonies of albatrosses are pro-tested by their isolation on islands with no natural predators, but the discovery by seafarers led to losses through egg-collecting and the killing of adults, followed by massive depredations for feathers which were used in clothing and bedding. Stiller’s albatrosses were almost wiped out by feather collectors; huge numbers of birds were killed; and a satiny colony of 20 pairs on Trachoma, off Japan, contains the survivors. The Laysanalbatross became a conservation problem when Midway Atoll was turned into a military airbase. The birds nested around the runways and installations and there were many deaths from collisions with aerial wires and aircraft.

Albatrosses face more insidious threats at sea. Contamination by oil spills and chemical pollution can occur, and albatrosses are known to suffer as “incidental catches” in fishing operations. As southern seas become exploited by the world’s fishing fleets there’s also the possibility that direct competition for krill or other marine species will affect the albatrosses, as well as other animals.

The shearwater family has one of the widest distributions of any bird family, ranging from the Snow petrels which nest 2 5 ohm (about z 5omi) inland in Antarctica to the Northern fulmar which breeds as far north there is the land in the Arctic. Although several species are localized and rare, others are abundant and undertake extensive migrations. Overall they are an extremely successful family. Some eat plankton, others dead whales, but the bulk catches small fish and squid at the sea surface or by underwater pursuit. Although there is a great variation between species in plumage and habits, the family divides neatly into four groups: fulmars, prisons, gadfly petrels, and true shearwaters.

The fulmars are a cold-water group, only venturing into the subtropics along cold-water currents. There are five species in the southern hemisphere, which is where the group probably evolved because the single northern species (the Northern fulmar) is closely related to the Southern fulmar. Most species are medium-sized, but the two sibling species of giant petrels (wingspan2M, 6ft) are as large as some albatrosses.

There is speculation that the albatross shooting Coleridge’s “Rime of the Ancient Mariner” (1798) was, in fact, a giant petrel. Fulmars’ bills are large (enormously so in giant petrels) and broad. They once probe-ably fed mainly on plankton, but some species now eat waste from fishing and whaling fleets; the exploitation of this new food resource has led to spectacular increases in numbers. Fulmars are fairly active on land and giant petrels can walk with upright shanks (tarsi); all other groups in this family shuffle with shanks flat on the ground. In-flight they alternate flapping and gliding.

Prisons (including the Blue petrel) are another southern group and breed mainly on sub-Antarctic islands but move into slightly warmer waters at other times. These small birds (length 26cm, loin) all look verisimilar, blue-gray above, white below withal dark “W” across the wings. All eat small plankton which they filter out with plates lamellae) on the bill, but the bill dimensions vary greatly suggesting subtle differences indict. Some species pick fish from the surface while those with broader beaks hydroplane their way through the surface water.

Prisons congregate in areas of high plank-ton density and vast flocks typically wheel low over the sea. They were once known as whale birds because they frequently occurred in the presence of whales.

Gadfly petrels are larger species (length26-46cm, o—r 8in) and are difficult to identify as some species have different color phases or variations. Most are black (or gray) and white above and white below with white faces; others are all dark. The shorthand stout bill with a powerful hook and sharp cutting edge is used for gripping and cutting up small squid and fish. They occur in the southern and tropical oceans. Some are restricted to single islands (egg theca how) while other species roam far and wide. They are strong fliers and typically arc high above the sea. Their movements are imperfectly known but some Pacific species migrate across the equator from one hemisphere to another.

The true shearwaters and petrels are small to large birds (length 27-55CM, 10.6-21.6in); most are dark above and black or white underneath. Many species have a Blackcap and only one species have a white head. Shearwaters are widespread and very mobile and pose considerable taxonomic problems; for example, should the similar, but not identical, black-and-white shearwaters breeding in the northeast Atlantic, Mediterranean, Hawaii, eastern Pacific, and New Zealand be considered subspecies of the Manx shearwater or spear-ate species? (A shearwater ringed in Britain was once recovered in Australia, and the whole of the British population migrates to South America each year: distance is thus no barrier to dispersal. indeed colonies are sometimes formed far outside the normal range, and during the last 20 years the Manx shearwater has started to breed off the coast of North America.)

Shearwater bills are proportionately longer and thinner than those of other groups but they still eat mainly fish and squid. Prey is caught either by the bird crashing down onto it or by swimming after it underwater. All the species in the family are colonial to a greater or lesser extent. Sometimes thesis due to limited suitable habitat; for example, Antarctic-nesting Southern giant petrels are forced to nest on the few patches of stones kept snow free by the wind, butut usually is by choice as birds enter and tyro nest in seemingly overcrowded areas even with apparently suitable, but unused habitat nearby. Colony sites are as diverse as the species themselves, but safety from predators is a prerequisite.

Of the fulmars, only the Snow petrel nests under cover; other species make scrape one cliff ledge or incubate the egg in the open. Birds discourage intruders by spitting or regurgitating foul-smelling oil, hence the old name of “stinker” for the giant petrel. Colonies tend to be small and nests dispersed. All the prisons nest underground among boulders or in burrows they dig themselves; colonies may be very large. Except for a few surface-living species on Pacific islands, gadfly petrels and shearwaters nest in burrows or under rocks. Some line the nest chamber with vegetation; others make a mere token of a nest. Typically colonies are large and found on islands, less commonly among forests or high on Mainland Mountains. Whereas open nesters come and go from their nests by day, most burrow nesters are nocturnal at the colonies, so as to escape predators. It has recently been demonstrated that some species locate their burrows by smell.

Breeding is remarkably uniform throughout the family. Birds return to the colonies at least a few weeks prior to nesting and reclaim the nest sites used the previous season. Pairs usually remain together from one season to the next, and probably meet again at the nest sites. Adult survival is extremely high (at least 90 percent perineum) and pairs persist for many years. When “divorces” occur, they usually follow unsuccessful breeding. In the weeks prior to laying, there are many noisy aerial displays and pairs spend days together at the nest. Many species have a “honeymoon” period. When the female leaves the colony for About two weeks to feed so as to lay down reserves for the large egg. In some species, the male is also away preparing himself forsaking the first long incubation stint. However, in others, he returns periodically to check the nest site.

In most species breeding is annual and synchronized. The most extreme case is the Short-tailed shearwater, whose colonies span it degrees latitude; all of its eggs are laid during a 12-day period with the peak always occurring between 24 and 26 November. In tropical species, which frequent the colonies throughout the year, eggs may be laid in all months. In a few species, individuals breed at less than annual intervals but in most species pairs still, breed annually. Even more rarely birds at adjacent colonies breed annually but are out of phase.

All species lay a single, very large white egg which varies from 6 percent (in the Giant-petrel) to 20 percent (in prisons) of the female’s weight. Tropical species lay proportionately larger eggs than temperate or polar species, probably because food is often short so the chick needs bigger food reserves at hatching to carry over any shortage. Both sexes have a single large central brood patch (i.e. an area denuded of feathers and rich in blood vessels for transferring heat from parent to egg) and incubate in turn for spells of 1-20 days. Often the male takes the first and longest stint, presumably to let the female go back to sea to recover from lying. Lost eggs are very rarely, usually never, replaced. Eggs are tolerant of chilling, especially those safe in the uniform temperature of a burrow, but chilling can increase the incubation period by up to 25 percent.

The incubation period is long but the range (43-6o days) is less than expected given the great range of egg sizes (25-237g, 0.9-8.4oz). The chick is brooded for the first few days, but may then be left in the burrow to allow both adults to forage. It is fed one soup of partly digested fish, crustacea, squid, etc, and on stomach oil. Growth is rapid until the young may be much heavier than the adult. Burrow-living chicks are often deserted and complete their development on stored fat.

The young, eggs, and adults of many species were once considered delicacies and were eaten in large numbers, and their fatwa’s used extensively. Human predation has declined but not stopped. For instance, Great shearwaters are still killed at the colonies on Tristan ad Conga and in wintering grounds in the North Atlantic. Some shearwaters are known as mutton birds and the young of one species, the Short-tailed shearwater are still harvested commercially for their meat; however, there is a strict quota and the harvest has no effect on the population. In contrast, several gadfly petrels are seriously threatened by habitat destruction and introduced predators. The chow or Bermuda petrel is a typical example. Occurring only in Bermuda it once lived inland where it was hunted for food and then killed by pigs, cats, and rats. A few pairs survived on offshore rocks but their breeding success was very low because of competition with tropic birds for nest sites. Management has prevented this and the species just hangs on. The Dark-romped petrel is similarly threatened at both its nesting areas, in the Galapagos by rats and pigs, dogs and farming, and in Hawaii by mongooses and rats. Several species of shearwaters and petrels will need help if they are to survive.

Storm petrels are the smallest and most deli-cater of seabirds. Their name may be derived from their habit of sheltering in the lee of the ship during severe storms and a corruption of St Peter since several common species appear to walk on the water while feeding.

Absent from brackish water and the Arc-tic, storm petrels can otherwise be found throughout the oceans. They are most abundant in the cold waters around Antarctica and in areas of marine upwellings, like the Humboldt Current off Peru. Some species occur only in the most desert-like areas of low biological productivity of the central tropical oceans, where there is apparently little food. A few species have very restricted distributions, others undertake long migrations. Wilson’s storm petrel which breeds around Antarctica spends its non-breeding time throughout the Indian, central Pacific, and Atlantic oceans north to Greenland. Storm petrels are not worried by man and many species feed in ships’ wakes and a few come around fishing boats to pick up scraps.

Storm petrels are immediately recognizable by their fairly small but strongly hooked beak, pronounced tubular nostrils that are fused together, and steep forehead. Despite the absence of color, many are striking birds with almost black plumage and white rump. Others are beautiful shades of brown and gray. The family is clearly divisible into two groups which presumably evolved in different hemispheres but which now overlap in the tropics. Species of the northern group, typified by Leach’s storm petrel, are black and white and most have pointed wings, and relatively short legs, and feed by swooping down and picking food from the surface, rather like terns. Species in the southern group typified by the White-faced storm petrel, have more variable plumage (including species with several color forms), rounded wings, and long legs which often are held down as the birds bounce or walk on the sea surface as they feed.

All species are colonial and most breed on isolated islands lacking ground predators. However, Hornsby’s storm petrels breed well inland high in the Andes. Except for the theWedge-rumped storm petrel, all species visit colonies at night or, in high latitudes, when light density is lowest. Pairs defend a burrow among rocks, tree roots, or (rarely) under abash and remain together from one season to the next. In temperate regions breeding is fairly well synchronized and seasonal while in the tropics it often appears pro-longed with birds present throughout the year. However, in the Galapagos Islands, the Madeira storm petrel has two breeding seasons a year due to two quite separate populations each of which breeds annually but at a different time. The single white egg is laid on the ground and incubated for 1-6 days by each bird intern for a total of 40 days. If lost the eggs were only very rarely replaced that season, probably because the egg is so large (up to 25 percent of the female’s weight) that it would take too long to produce another.

The young are fed a mixture of partly digested food and stomach oil. It fledges alone, and at night, after 59-73 days. Although fed less frequently near to fledging it is not, as is often said, deserted and the adults may visit the burrow after it has left.

Storm petrels eat mainly planktonic crustacea, squid and fish, and oily scraps picked up in flight (indeed storm petrels rarely sit on the water).

In some species, many immature visit other colonies before they breed (usually 4-5 years) and these can even be attracted to toothier places by playing tape recordings of the purring calls. The potential conservation value of this has been demonstrated byte the National Audubon Society of the US which persuaded Leach’s storm petrel to nest in artificial burrows on an island where they had never bred before.

One of the amazing sights in the southern seas is a small flock of diving petrels flying through a steep wave, plunging in one side and coming out the other, or erupting from the depths of the sea without check. These are impossible thanks to the adaptation of wings for swimming underwater. Diving petrels are a southern equivalent of the auk family, resembling the Little auk in particular; both have small wings for swimming underwater and a whirring “bumblebee” flight. There’s even a remarkable similarity in the structure of wing bones.

Breeding is confined to cool waters north of 60 degrees south and up the Western side of South America, where the sea temperature is influenced by the cool Humboldt Current. Unlike many other petrels, diving petrels do not appear to make extensive movements, even outside the breeding season; they are usually seen in waters over the continental shelf near the breeding area.

The four species of diving petrels are very similar in size and plumage, which makes identification difficult unless the bird is in the hand and the variable amounts of grayer white on the upper side can be seen. Only the Magellan diving petrel is distinctive with its white collar; it also has a distinguishable juvenile that lacks the white fringes on feathers on the back.

Diving petrels chase their prey by swim-Ming underwater and feed mainly within the upper loin (33ft). The diet consists of small marine organisms, but detailed analysis has been made only on Common and Georgian diving petrels in South Georgia. Their Georgian diving petrels fed their chicks 76 percent krill (by volume) with lesser amounts of amphipod and Copepod crustaceans, while Common diving petrels delivered 68 percent copepods and lesser amounts of amphipods and euphausiids.

Breeding has similarly been described in detail in South Georgia for Georgian and Common diving petrels. Diving petrel’s nesting burrows are excavated each season. The birds fly in at night, presumably to avoid predation by scubas. The Georgian diving petrel tunnels into bare stony soil above the level of vegetation, whereas Common diving petrels nest in peaty, often waterlogged, the soil beneath stands of tussock grass at lower levels. The birds are heard calling at night; the Georgian diving petrel makes a series of harsh “squeaks,” the Common diving petrel
Utters a two-syllable phrase the Maori name of the species.

The Georgian diving petrel lays a single egg between 7 and 31 December which it hatches in late January. The Common div-in petrel hatches on average 29 days earlier than the Georgian. Incubation spells last one to three days. After hatching, chicks of the Common diving petrel brooded format least I days, but Georgian chicks recovered for five days less. The chicks are felon most nights by one or both parents. The feed contains very little stomach oil, unlike that of other members of the order, and is little digested, possibly because the feed is delivered so quickly after capture. Peruvian diving petrels nest under boulders and have suffered as islands have been stripped of guano (excrement). The Magellan diving petrel appears to nest in peaty soil.

Colonies of diving petrels can be extensive; there are an estimated two million breeding pairs of Georgian diving petrels in South Georgia and the only current threat of predation by introduced rats. Forth Peruvian diving petrel, however, the status is unclear. Only a few breeding sites are known; some have been destroyed byte clearance of guano and the future of the species is a cause for concern. 

See more: WHAT IS A BIRD?