The American white pelican [1] ( lat. Pelecanus erythrorhynchos ) is a bird of the pelican family. Native to North America . The sizes are large: the wingspan is up to 3 m. This pelican is called the “pelican-rhinoceros”, for growth in the middle of the upper mandible, appearing in the mating season. Eats more than 1.5 kg of fish per day ( carp , chub , perch , pike ). Eggs of the female lay in a hole in the ground. This pelican nests from Western Canada through the central and western states of the United States , Florida and Mexico up to Panama . They overwinter in central California and on the Pacific coast of Guatemala , as well as along the shores of the Gulf of Mexico . It is protected by the Migratory Bird Treaty Act (Agreement on Migratory Birds) of 1972 .
American White Pelican | |||||||||||||||||||||||||||||||||
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Pelecanus erythrorhynchos Gmelin , 1789 | |||||||||||||||||||||||||||||||||
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Content
General Information
The American white pelican is one of two species of pelicans (along with the brown pelican ), which are found in North America . This species of birds was first described by the German naturalist Gmelin in 1788 . He gave him the species name "erythrorynchos" , which translated from Greek means "red-billed" .
The American white pelican is a rather large bird and is of medium size among the representatives of the pelican family:
- body length 127-165 cm
- wingspan 2.4-2.9 meters.
- weight varies between 4.5-13.5 kg, an average of 6-8 kg.
- male wing length 57.5-63 cm, females 52.5-60.3 cm.
- tail length of males 15.3-16.7 cm, females 13.5-16.6 cm.
- the length of the male coxalum is 11.5–13 cm, females 10.8–12.3 cm
- the length of the beak of males is 32-36.5, females 26.5-32 cm. [2]
The color is almost entirely bright white, with black wing feathers, which are clearly visible only in flight. A large beak with a throat sac on the lower jaw is painted in a dark pink color, the legs are orange.
At the beginning of the mating season, the beak and legs acquire a bright orange hue (fading with time), a small white plume appears on the back of the head, and a flat, vertical orange comb and, usually, a triangular shape appears on the upper jaw. This comb is inherent only in this species of pelicans, and is a characteristic feature of the species.
Pelicans of this species reach sexual maturity at the age of 3 years, and under natural conditions can live to 25 years.
Spread
The Red-billed Pelican can inhabit a wide range of aquatic biotopes , including rivers , lakes , artificial reservoirs of any size, estuaries , wetlands and sea coasts. All these biotopes are used for nesting, feeding and resting. Usually on vacation, pelicans are located on small islands in the midst of water bodies, long peninsulas and on steep cliffs that protect them from predatory mammals. Gnezdovye colonies are usually located on the islands in the midst of fresh or saline water bodies or, rarely, on the peninsulas.
The northern boundary of nesting passes approximately 61 ° north latitude. This species of pelican is quite common in the United States and Canada , but has become quite rare on the Atlantic coast of the continent to the north of the Florida Peninsula in the last 100 years.
Gnezdovye colonies and places of food can be in the same place for 50-70 years. One of the largest populations of the red-billed pelican over the past 30 years is located on Lake Aptekarskoye in the state of Montana ( USA ).
Power
Reservoirs that pelicans use for feeding may be located at a distance of 100 or more (up to 300) kilometers from their permanent habitat.
This species of pelicans feeds on fish ( carp , pike , perch , minnow , on salt and brackish ponds - gobies , mullet ), and amphibians ( toads , tritons ) and their larvae (tadpoles and large tiger-amber larvae). During nesting in colonies in the interior of the United States and Canada , the proportion of the American dwarf catfish sharply increases in the diet of pelicans. Also, especially in marine areas, pelicans consume crustaceans ( shrimps , crabs ). Pelicans can hunt alone or in groups, surrounding the fish and driving it to shallow water. In the case of joint hunting with other species of birds (most often - with eared cormorants ), theft of prey from birds of another species (kleptoparasitism) is common.
An adult pelican usually consumes a day amount of food, amounting to 20-40% of the weight of his body (approximately 1.8 kg).
Migrations
The American white pelican during seasonal migrations is capable of covering fairly long distances: the main wintering areas are in Florida , on the coast of the Gulf of Mexico from the north of Florida to the Yucatan Peninsula in Mexico , and on the Pacific coast of the continent from northern California to southern Honduras . Also, according to some reports, small wintering colonies can occur from year to year in the interior of the United States . It is interesting that different birds from the same colony can fly for wintering both to the western wintering territories ( Mexican coast of the Caribbean ) and to the eastern ones ( Florida ).
In flight, a flock of pelicans is built in one or several oblique lines, with each next bird imitating the flight of the previous one, therefore the whole flock usually flaps its wings in synchrony or moves on to a planning flight.
Usually birds return for reproduction to the same colony where they were born, but exceptions are possible.
Reproduction
Pelicans are highly socialized, and are usually found throughout the year as part of a pack. But when breeding, the schools additionally unite, and create breeding colonies with an average size of more than 1000 pairs (the largest up to 5-5,5 thousand).
Usually, American white pelicans arrive at the sites of nesting colonies in late March-April, laying eggs and incubating take place from late April to late May; chicks hatch in early June. However, in some territories (on the borders of the range) deviations from the general schedule are observed: in Texas, pelicans lay eggs in May-July, and in Canada, nesting begins in May or even in June, and the hatching of chicks in the first nests may outpace the laying of eggs in last.
Nesting
This species of pelicans usually nests on islands in the midst of ponds or on well-isolated peninsulas. A nest with a diameter of 30-50 centimeters is built on the ground, in small depressions or on low embankments (if the place is wet) from fragments of branches, plant debris and soil, on level ground or on a slight slope. In this case, both natural and artificial islands can be used, for example, arisen during the operation of dredgers and other similar machines. Typically, nests are located in an open area, but almost always near the thickets of reeds or shrubs, smoothly, or under rocks. Nesting colonies of the American white pelican are usually mixed with the nests of other near-water birds: eared cormorant , common snake , different types of herons, and gulls .
The clutch size is 1-3 eggs (most often - 2) approximately 8.9 by 5.9 centimeters in size, off-white. Despite this number of eggs, cases where one pair of pelicans grows more than one chick are very rare. Hatching eggs lasts 31-32 days, and both parents take part in taking care of the chicks. When chicks start feeding, adult pelicans lose a crest on their beak, the back surface of the head becomes dark in color, and their eyes brighten.
Nestlings leave the nest at the age of 17-28 days, still incapable of flight, and form large groups inside the colony. In most colonies, young birds fly away at the end of August, at the age of 10-11 weeks and approximately 1 week after their first flight.
Young birds, unlike adults, have plumage with noticeable gray-brown tones, and become completely white only from the time of puberty.
On average, the proportion of successful hatching in the American colonies is ~ 0.5-0.7 chicks per nest. The death of eggs and chicks is quite high, and pelicans usually do not re-lay in the event of the first death.
Limiting factors
Adverse weather conditions, especially severe thunderstorms with hail, can sometimes lead to significant death of adults and, especially, young pelicans.
The main predators that threaten nesting colonies of pelicans are crows , some species of large gulls (break eggs when there are no pelicans on the nest), coyotes , foxes , and wolves in Canada . Owls and eagles also hunt chicks.
The major threats to this species are the regulation of water bodies and the pollution of their habitat by chemicals (especially pesticides ), as well as the activities of people in nesting territories. Also in some places, mainly in Latin American countries, the pelican is being hunted.
Although this species is not endangered, it has already become quite rare in some territories.
Notes
- ↑ Boehme RL , Flint V. Ye. The five-language dictionary of animal names. Birds. Latin, Russian, English, German, French / Under total. ed. Acad. V.E. Sokolova . - M .: Rus. lang, "RUSSO", 1994. - p. 20. - 2030 copies. - ISBN 5-200-00643-0 .
- ↑ Pelicans, Cormorants, and Their Relatives: The Pelecaniformes J. Bryan Nelson Oxford University Press, 2006, p. 677