Pulcinella di mare

Identificazione

The Atlantic puffin is sturdily built with a thick-set neck and short wings and tail. It is 28 to 30 cm (11 to 12 in) in length from the tip of its stout bill to its blunt-ended tail. Its wingspan is 47 to 63 cm (19 to 25 in) and on land it stands about 20 cm (8 in) high. The male is generally slightly larger than the female, but they are coloured alike. The forehead, crown, and nape are glossy black, as are the back, wings, and tail. A broad, black collar extends around the neck and throat. On each side of the head is a large, lozenge-shaped area of very pale grey. These face patches taper to a point and nearly meet at the back of the neck. The shape of the head creates a crease extending from the eye to the hindmost point of each patch, giving the appearance of a grey streak. The eyes look almost triangular because of a small, peaked area of horny blue-grey skin above them and a rectangular patch below. The irises are brown or very dark blue, and each has a red orbital ring. The underparts of the bird, the breast, belly, and under tail coverts, are white. By the end of the breeding season, the black plumage may have lost its shine or even taken on a slightly brown tinge. The legs are short and set well back on the body, giving the bird its upright stance when on land. Both legs and large webbed feet are bright orange, contrasting with the sharp, black claws.: 19–23 <p>The beak is very distinctive. From the side, the beak is broad and triangular, but viewed from above, it is narrow. The half near the tip is orange-red and the half near the head is slate grey. A yellow, chevron-shaped ridge separates the two parts, with a yellow, fleshy strip at the base of the bill. At the joint of the two mandibles is a yellow, wrinkled rosette. The exact proportions of the beak vary with the age of the bird. In an immature individual, the beak has reached its full length, but it is not as broad as that of an adult. With time the bill deepens, the upper edge curves, and a kink develops at its base. As the bird ages, one or more grooves may form on the red portion.: 19–23  The bird has a powerful bite.<p>The characteristic bright orange bill plates and other facial characteristics develop in the spring. At the close of the breeding season, these special coatings and appendages are shed in a partial moult. This makes the beak appear less broad, the tip less bright, and the base darker grey. The eye ornaments are shed and the eyes appear round. At the same time, the feathers of the head and neck are replaced and the face becomes darker. This winter plumage is seldom seen by humans because when they have left their chicks, the birds head out to sea and do not return to land until the next breeding season. The juvenile bird is similar to the adult in plumage, but altogether duller with a much darker grey face and yellowish-brown beak tip and legs. After fledging, it makes its way to the water and heads out to sea, and does not return to land for several years. In the interim, each year, it will have a broader bill, paler face patches, and brighter legs and beaks.: 19–23 <p>The Atlantic puffin has a direct flight, typically 10 m (35 ft) above the sea surface and higher over the water than most other auks. It mostly moves by paddling along efficiently with its webbed feet and seldom takes to the air.: 43  It is typically silent at sea, except for the soft purring sounds it sometimes makes in flight. At the breeding colony, it is quiet above ground, but in its burrow makes a growling sound somewhat resembling a chainsaw being revved up.

Tassonomia

The Atlantic puffin is a species of seabird in the order Charadriiformes. It is in the auk family, Alcidae, which includes the guillemots, typical auks, murrelets, auklets, puffins, and the razorbill. The rhinoceros auklet (Cerorhinca monocerata) and the puffins are closely related, together composing the tribe Fraterculini. The Atlantic puffin is the only species in the genus Fratercula to occur in the Atlantic Ocean. Two other species are known from the northeast Pacific, the tufted puffin (Fratercula cirrhata) and the horned puffin (Fratercula corniculata), the latter being the closest relative of the Atlantic puffin.<p>The generic name Fratercula comes from the Medieval Latin fratercula, friar, a reference to their black and white plumage, which resembles monastic robes. The specific name arctica refers to the northerly distribution of the bird, being derived from the Greek ἄρκτος (arktos), the bear, referring to the northerly constellation, the Ursa Major (Great Bear). The vernacular name "puffin" – puffed in the sense of swollen – was originally applied to the fatty, salted meat of young birds of the unrelated species Manx shearwater (Puffinus puffinus), which in 1652 was known as the "Manks puffin". It is an Anglo-Norman word (Middle English pophyn or poffin) used for the cured carcasses. The Atlantic puffin acquired the name at a much later stage, possibly because of its similar nesting habits, and it was formally applied to Fratercula arctica by Pennant in 1768. While the species is also known as the common puffin, "Atlantic puffin" is the English name recommended by the International Ornithological Congress.<p>The three subspecies generally recognized are:<p>The only morphological difference between the three is their size. Body length, wing length, and size of beak all increase at higher latitudes. For example, a puffin from northern Iceland (subspecies F. a. naumanii) weighs about 650 g (1 lb 7 oz) and has a wing length of .mw-parser-output .frac{white-space:nowrap}.mw-parser-output .frac .num,.mw-parser-output .frac .den{font-size:80%;line-height:0;vertical-align:super}.mw-parser-output .frac .den{vertical-align:sub}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}186 mm (7+5⁄16 in), while one from the Faroes (subspecies F. a. grabae) weighs 400 g (0.9 lb) and has a wing length of 158 mm (6.2 in). Individuals from southern Iceland (subspecies F. a. arctica) are intermediate between the other two in size. Ernst Mayr has argued that the differences in size are clinal and are typical of variations found in the peripheral population and that no subspecies should be recognised.

Nome scientifico

Fratercula arctica

Autorità

(Linnaeus, 1758)

Ordine

Caradriformi

Famiglia

Alcidi

Genere

Fratercula

Areale e habitat

The Atlantic puffin is a bird of the colder waters of the North Atlantic Ocean. It breeds on the coasts of northwest Europe, the Arctic fringes, and eastern North America. More than 90% of the global population is found in Europe (4,770,000–5,780,000 pairs, equaling 9,550,000–11,600,000 adults) and colonies in Iceland alone are home to 60% of the world's Atlantic puffins. The largest colony in the western Atlantic (estimated at more than 260,000 pairs) can be found at the Witless Bay Ecological Reserve, south of St. John's, Newfoundland and Labrador. Other major breeding locations include the north and west coasts of Norway, the Faroe Islands, Shetland and Orkney, the west coast of Greenland, and the coasts of Newfoundland. Smaller-sized colonies are also found elsewhere in the British Isles, the Murmansk area of Russia, Novaya Zemlya, Spitzbergen, Labrador, Nova Scotia, and Maine. Islands seem particularly attractive to the birds for breeding as compared to mainland sites,: 24–29  likely to avoid predators.<p>While at sea, the bird ranges widely across the North Atlantic Ocean, including the North Sea, and may enter the Arctic Circle. In the summer, its southern limit stretches from northern France to Maine; in the winter, the bird may range as far south as the Mediterranean Sea and North Carolina. These oceanic waters have such a vast extent of 15×10^6–30×10^6 km2 (6×10^6–12×10^6 sq mi) that each bird has more than 1 km2 of range at its disposal, so is seldom seen out at sea.: 30  In Maine, light-level geolocators have been attached to the legs of puffins, which store information on their whereabouts. The birds need to be recaptured to access the information, a difficult task. One bird was found to have covered 7,700 km (4,800 mi) of the ocean in 8 months, traveling northwards to the northern Labrador Sea then southeastward to the mid-Atlantic before returning to land.<p>In a long-living bird with a small clutch size, such as the Atlantic puffin, the survival rate of adults is an important factor influencing the success of the species. Only 5% of the ringed puffins that failed to reappear at the colony did so during the breeding season. The rest were lost some time between departing from land in the summer and reappearing the following spring. The birds spend the winter widely spread out in the open ocean, though a tendency exists for individuals from different colonies to overwinter in different areas. Little is known of their behaviour and diet at sea, but no correlation was found between environmental factors, such as temperature variations, and their mortality rate. A combination of the availability of food in winter and summer probably influences the survival of the birds, since individuals starting the winter in poor condition are less likely to survive than those in good condition.

Areale riproduttivo

PAL, NA : subarctic and temperate North Atlantic coasts: w, ec Greenland, Iceland, Faroe, British, and Channel is., nw France, s to n Scandinavia, Svalbard (n of Norway) and Novaya Zemlya (nw Russia); n Hudson Bay to se Canada and Maine (e Canada, ne USA)

Areale non riproduttivo

pelagic in North Atlantic and marginal seas, to North Carolina in Gulf Stream of w North Pacific and to Azores (n Macaronesia, nw of Africa) and Iberian Pen.

Migrazione

Complete migrants

Comportamento

Like many seabirds, the Atlantic puffin spends most of the year far from land in the open ocean and only visits coastal areas to breed. It is a sociable bird and it usually breeds in large colonies.<p>Atlantic puffins lead solitary existences when out at sea, and this part of their lives has been little studied, as the task of finding even one bird on the vast ocean is formidable. When at sea, they bob about like a cork, propelling themselves through the water with powerful thrusts of their feet and keeping turned into the wind, even when resting and apparently asleep. They spend much time each day preening to keep their plumage in order and spread oil from their preen glands. Their downy under plumage remains dry and provides thermal insulation. In common with other seabirds, their upper surface is black and underside white. This provides camouflage, with aerial predators unable to locate the birds against the dark, watery background, and underwater attackers fail to notice them as they blend in with the bright sky above the waves.: 30–43 <p>When it takes off, the Atlantic puffin patters across the surface of the water while vigorously flapping its wings, before launching itself into the air.: 30–43  The size of the wing has adapted to its dual use, both above and below the water, and its surface area is small relative to the bird's weight. To maintain flight, the wings must beat very rapidly at a rate of several times each second. The bird's flight is direct and low over the surface of the water, and it can travel at 80 km/h (50 mph). Landing is awkward; it either crashes into a wave crest or in calmer water, does a belly flop. While at sea, the Atlantic puffin has its annual moult. Land birds mostly lose their primaries one pair at a time to enable them still to be able to fly, but the puffin sheds all its primaries at one time and dispenses with flight entirely for a month or two. The moult usually takes place between January and March, but young birds may lose their feathers a little later in the year.: 30–43 <p>The Atlantic puffin diet consists almost entirely of fish, though examination of its stomach contents shows that it occasionally eats shrimp, other crustaceans, molluscs, and polychaete worms, especially in more coastal waters. When fishing, it swims underwater using its semi-extended wings as paddles to "fly" through the water and its feet as a rudder. It swims fast and can reach considerable depths and stay submerged for up to a minute. It can eat shallow-bodied fish as long as 18 cm (7 in), but its prey is commonly smaller fish, around 7 cm (3 in) long. An adult bird needs to eat an estimated 40 of these per day – sand eels, herring, capelin, and sprats being the most often consumed.<p>It fishes by sight and can swallow small fish while submerged, but larger specimens are brought to the surface. It can catch several small fish in one dive, holding the first ones in place in its beak with its muscular, grooved tongue while it catches others. The two mandibles are hinged in such a way that they can be held parallel to hold a row of fish in place and these are also retained by inward-facing serrations on the edges of the beak. It copes with the excess salt that it swallows partly through its kidneys and partly by excretion through specialised salt glands in its nostrils.: 30–43 <p>In the spring, mature birds return to land, usually to the colony where they were hatched. Birds that were removed as chicks and released elsewhere were found to show fidelity to their point of liberation. They congregate for a few days on the sea in small groups offshore before returning to the cliff-top nesting sites. Each large puffin colony is divided into subcolonies by physical boundaries such as stands of bracken or gorse. Early arrivals take control of the best locations, the most desirable nesting sites being the densely packed burrows on grassy slopes just above the cliff edge where take-off is most easily accomplished. The birds are usually monogamous, but this is the result of their fidelity to their nesting sites rather than to their mates, and they often return to the same burrows year after year. Later arrivals at the colony may find that all the best nesting sites have already been taken, so are pushed towards the periphery, where they are in greater danger of predation. Younger birds may come ashore a month or more after the mature birds and find no remaining nesting sites. They do not breed until the following year, although if the ground cover surrounding the colony is cut back before these subadults arrive, the number of successfully nesting pairs may be increased.: 44–65 <p>Atlantic puffins are cautious when approaching the colony, and no bird likes to land in a location where other puffins are not already present. They make several circuits of the colony before alighting. On the ground, they spend much time preening, spreading oil from their preen gland, and setting each feather in its correct position with beak or claw. They also spend time standing by their burrow entrances and interacting with passing birds. Dominance is shown by an upright stance, with fluffed chest feathers and a cocked tail, an exaggerated slow walk, head jerking, and gaping. Submissive birds lower their heads and hold their bodies horizontally and scurry past dominant individuals. Birds normally signal their intention to take off by briefly lowering their bodies before running down the slope to gain momentum. If a bird is startled and takes off unexpectedly, panic can spread through the colony with all the birds launching themselves into the air and wheeling around in a great circle. The colony is at its most active in the evening, with birds standing outside their burrows, resting on the turf, or strolling around. Then, the slopes empty for the night as the birds fly out to sea to roost, often choosing to do so at fishing grounds ready for early-morning provisioning.: 44–65 <p>The puffins are energetic burrow engineers and repairers, so the grassy slopes may be undermined by a network of tunnels. This causes the turf to dry out in summer, vegetation to die, and dry soil to be whirled away by the wind. Burrows sometimes collapse, and humans may cause this to happen by walking incautiously across nesting slopes. A colony on Grassholm was lost through erosion when so little soil was left that burrows could not be made.: 48  New colonies are very unlikely to start up spontaneously because this gregarious bird only nests where others are already present. Nevertheless, the Audubon Society had success on Eastern Egg Rock Island in Maine, where, after a gap of 90 years, puffins were reintroduced and started breeding again. By 2011, over 120 pairs were nested on the small islet. On the Isle of May on the other side of the Atlantic, only five pairs of puffins were breeding in 1958, while 20 years later, 10,000 pairs were present.: 47 <p>Having spent the winter alone on the ocean, whether the Atlantic puffin meets its previous partner offshore or whether they encounter each other when they return to their nest of the previous year is unclear. On land, they soon set about improving and clearing out the burrow. Often, one stands outside the entrance while the other excavates, kicking out quantities of soil and grit that showers the partner standing outside. Some birds collect stems and fragments of dry grasses as nesting materials, but others do not bother. Sometimes, a beakful of materials is taken underground, only to be brought out again and discarded. Apart from nest-building, the other way in which the birds restore their bond is by billing. This is a practice in which the pair approaches each other, each wagging their heads from side to side, and then rattling their beaks together. This seems to be an important element of their courtship behaviour because it happens repeatedly, and the birds continue to the bill, to a lesser extent, throughout the breeding season.: 72 <p>Atlantic puffins are sexually mature at 4–5 years old. They are colonial nesters, excavating burrows on grassy clifftops or reusing existing holes, and on occasion may nest in crevices and among rocks and scree, in competition with other birds and animals for burrows. They can excavate their own hole or move into a pre-existing system dug by a rabbit, and have been known to peck and drive off the original occupant. Manx shearwaters also nest underground and often live in their own burrows alongside puffins, and their burrowing activities may break through into the puffin's living quarters, resulting in the loss of the egg.: 107  They are monogamous (mate for life) and give biparental care to their young. The male spends more time guarding and maintaining the nest, while the female is more involved in incubation and feeding the chick.<p>Egg-laying starts in April in more southerly colonies but seldom occurs before June in Greenland. The female lays a single white egg each year, but if this is lost early in the breeding season, another might be produced.: 78–81  Synchronous laying of eggs is found in Atlantic puffins in adjacent burrows. The egg is large compared to the size of the bird, averaging 61 mm (2+3⁄8 in) long by 42 mm (1+5⁄8 in) wide and weighing about 62 g (2+3⁄16 oz). The white shell is usually devoid of markings, but soon becomes covered with mud. The incubation responsibilities are shared by both parents. They each have two feather-free brood patches on their undersides, where an enhanced blood supply provides heat for the egg. The parent on incubation duty in the dark nest chamber spends much of its time asleep with its head tucked under its wing, occasionally emerging from the tunnel to flap dust out of its feathers or take a short flight down to the sea.: 78–81 <p>The total incubation time is around 39–45 days. From above ground level, the first evidence that hatching has taken place is the arrival of an adult with a beak-load of fish. For the first few days, the chick may be fed with this beak-to-beak, but later the fish are simply dropped on the floor of the nest beside the chick, which swallows them whole. The chick is covered in fluffy black down, its eyes are open, and it can stand as soon as it is hatched. Initially weighing about 42 g (1+1⁄2 oz), it grows at the rate of 10 g (3⁄8 oz) per day. Initially, one or the other parent broods it, but as its appetite increases, it is left alone for longer periods. Observations of a nest chamber have been made from an underground hide with a peephole. The chick sleeps much of the time between its parents' visits and also involves itself in bouts of exercise. It rearranges its nesting material, picks up and drops small stones, flaps its immature wings, pulls at protruding root ends, and pushes and strains against the unyielding wall of the burrow. It makes its way towards the entrance or along a side tunnel to defecate. The growing chick seems to anticipate the arrival of an adult, advancing along the burrow just before it arrives, but not emerging into the open air. It retreats to the nest chamber as the adult bird brings in its load of fish.: 82–95 <p>Hunting areas are often located 100 km (62 mi) or more offshore from the nest sites, although when feeding their young, the birds venture out only half that distance. Adults bringing fish to their chicks tend to arrive in groups. This is thought to benefit the bird by reducing kleptoparasitism by the Arctic skua, which harasses puffins until they drop their fish loads. Predation by the great skua (Catharacta skua) is also reduced by several birds arriving simultaneously.<p>In the Shetland Islands, sand eels (Ammodytes marinus) normally form at least 90% of the food fed to chicks. In years when the availability of sand eels was low, breeding success rates fell, with many chicks starving to death. In Norway, the herring (Clupea harengus) is the mainstay of the diet. When herring numbers dwindled, so did puffin numbers. In Labrador, the puffins seemed more flexible and when the staple forage fish capelin (Mallotus villosus) declined in availability, they were able to adapt and feed the chicks on other prey species.<p>The chicks take from 34 to 50 days to fledge, the period depending on the abundance of their food supply. In years of fish shortage, the whole colony may experience a longer fledgling period, but the normal range is 38 to 44 days, by which time chicks have reached about 75% of their mature body weight. The chick may come to the burrow entrance to defecate, but does not usually emerge into the open: 85–99  and seems to have an aversion to light until it is nearly fully fledged. Although the supply of fish by the adults reduces over the last few days spent in the nest, the chick is not abandoned as happens in the Manx shearwater. On occasions, an adult has been observed provisioning a nest even after the chick has departed. During the last few days underground, the chick sheds its down and the juvenile plumage is revealed. Its relatively small beak and its legs and feet are a dark colour, and it lacks the white facial patches of the adult. The chick finally leaves its nest at night, when the risk of predation is at its lowest. When the moment arrives, it emerges from the burrow, usually for the first time, and walks, runs, and flaps its way to the sea. It cannot fly properly yet, so descending a cliff is perilous; when it reaches the water, it paddles out to sea, and maybe 3 km (1.9 mi) away from the shore by daybreak. It does not congregate with others of its kind and does not return to land for 2–3 years.: 85–99

Conservazione

Tendenza della popolazione

declining