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72-590: Animal life in the Shadegan ponds include two species of amphibians, five species of reptiles and 154 species of birds, among them pelican and flamingo . The area is also known for its birds of prey and is very important to migratory birds. There are also 40 species of mammals present, among them the Iranian wolf , river otter , jungle cat and wild boar . The area suffers from pollution from leaking oil pipes, industrial waste and agricultural fertilisers. However,

144-405: A genus of large water birds that make up the family Pelecanidae . They are characterized by a long beak and a large throat pouch used for catching prey and draining water from the scooped-up contents before swallowing. They have predominantly pale plumage, except for the brown and Peruvian pelicans . The bills, pouches, and bare facial skin of all pelicans become brightly coloured before

216-594: A complex communal courtship involving a group of males chasing a single female in the air, on land, or in the water while pointing, gaping, and thrusting their bills at each other. They can finish the process in a day. The tree-nesting species have a simpler process in which perched males advertise for females. The location of the breeding colony is constrained by the availability of an ample supply of fish to eat, although pelicans can use thermals to soar and commute for hundreds of kilometres daily to fetch food. The Australian pelican has two reproductive strategies depending on

288-588: A complex mixture of many different elements from different sources (not all from dissolved salts) in different molecular forms. The chemical properties of some of these forms depend on temperature and pressure. Many of these forms are difficult to measure with high accuracy, and in any case complete chemical analysis is not practical when analyzing multiple samples. Different practical definitions of salinity result from different attempts to account for these problems, to different levels of precision, while still remaining reasonably easy to use. For practical reasons salinity

360-490: A few percent (%). Physical oceanographers working in the abyssal ocean , however, are often concerned with precision and intercomparability of measurements by different researchers, at different times, to almost five significant digits . A bottled seawater product known as IAPSO Standard Seawater is used by oceanographers to standardize their measurements with enough precision to meet this requirement. Measurement and definition difficulties arise because natural waters contain

432-625: A fish eater, the Australian pelican is also an eclectic and opportunistic scavenger and carnivore that forages in landfill sites, as well as taking carrion and "anything from insects and small crustaceans to ducks and small dogs". Food is not stored in a pelican's throat pouch, contrary to popular folklore. Pelicans may also eat birds. In southern Africa, eggs and chicks of the Cape cormorant are an important food source for great white pelicans. Several other bird species have been recorded in

504-591: A long history of cultural significance in mythology , and in Christian and heraldic iconography . The name comes from the Ancient Greek word pelekan (πελεκάν), which is itself derived from the word pelekys (πέλεκυς) meaning "axe". In classical times, the word was applied to both the pelican and the woodpecker. The genus Pelecanus was first formally described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae . He described

576-456: A measured density. Marine waters are those of the ocean, another term for which is euhaline seas . The salinity of euhaline seas is 30 to 35 ‰. Brackish seas or waters have salinity in the range of 0.5 to 29 ‰ and metahaline seas from 36 to 40 ‰. These waters are all regarded as thalassic because their salinity is derived from the ocean and defined as homoiohaline if salinity does not vary much over time (essentially constant). The table on

648-519: A phenomenon known as ground effect to reduce drag and increase lift . As the air flows between the wings and the water surface, it is compressed to a higher density and exerts a stronger upward force against the bird above. Hence, substantial energy is saved while flying. Adult pelicans rely on visual displays and behaviour to communicate, particularly using their wings and bills. Agonistic behaviour consists of thrusting and snapping at opponents with their bills, or lifting and waving their wings in

720-492: A similar technique is the Peruvian pelican, but its dives are typically from a lower height than the brown pelican. The Australian and American white pelicans may feed by low plunge-dives landing feet-first and then scooping up the prey with the beak, but they—as well as the remaining pelican species—primarily feed while swimming on the water. Aquatic prey is most commonly taken at or near the water surface. Although principally

792-420: A threatening manner. Adult pelicans grunt when at the colony, but are generally silent elsewhere or outside breeding season. Conversely, colonies are noisy, as chicks vocalise extensively. Pelicans are gregarious and nest colonially. Pairs are monogamous for a single season, but the pair bond extends only to the nesting area; mates are independent away from the nest. The ground-nesting (white) species have

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864-412: A valid description. Fossil finds from North America have been meagre compared with Europe, which has a richer fossil record. Several Pelecanus species have been described from fossil material, including: Pelicans are very large birds with very long bills characterised by a downcurved hook at the end of the upper mandible, and the attachment of a huge gular pouch to the lower. The slender rami of

936-545: A varied taxonomic history. Tropicbirds , darters , cormorants, gannets, boobies, and frigatebirds, all traditional members of the order, have since been reclassified: tropicbirds into their own order, Phaethontiformes , and the remainder into the Suliformes. In their place, herons, ibises, spoonbills, the hamerkop, and the shoebill have now been transferred into the Pelecaniformes. Molecular evidence suggests that

1008-436: A week, they are able to put their heads into their parents' pouches and feed themselves. Sometimes before, but especially after being fed the pelican chick may seem to "throw a tantrum" by loudly vocalizing and dragging itself around in a circle by one wing and leg, striking its head on the ground or anything nearby and the tantrums sometimes end in what looks like a seizure that results in the chick falling briefly unconscious;

1080-464: A wide range of salinities is euryhaline . Salts are expensive to remove from water, and salt content is an important factor in water use, factoring into potability and suitability for irrigation . Increases in salinity have been observed in lakes and rivers in the United States, due to common road salt and other salt de-icers in runoff. The degree of salinity in oceans is a driver of

1152-466: A wingspan of as little as 1.83 m (6.0 ft). The largest is believed to be the Dalmatian, at up to 15 kg (33 lb) and 1.83 m (6.0 ft) in length, with a maximum wingspan of 3 m (9.8 ft). The Australian pelican's bill may grow up to 0.5 m (1.6 ft) long in large males, the longest of any bird. Pelicans have mainly light-coloured plumage, the exceptions being

1224-698: Is considered to be near threatened in the IUCN Red List of Threatened Species. Numbers declined substantially during the 20th century, one crucial factor being the eradication of the important Sittaung valley breeding colony in Burma through deforestation and the loss of feeding sites. The chief threats it faces are from habitat loss and human disturbance, but populations have mostly stabilised following increased protection in India and Cambodia. Water salinity Salinity ( / s ə ˈ l ɪ n ɪ t i / )

1296-463: Is darker than that of adults. Newly hatched chicks are naked and pink, darkening to grey or black after 4 to 14 days, then developing a covering of white or grey down . Anatomical dissections of two brown pelicans in 1939 showed that pelicans have a network of air sacs under their skin situated across the ventral surface including the throat, breast, and undersides of the wings, as well as having air sacs in their bones. The air sacs are connected to

1368-545: Is highly variable. Pelicans live for 15 to 25 years in the wild, although one reached an age of 54 years in captivity. The diet of pelicans usually consists of fish, but occasionally amphibians , turtles, crustaceans , insects , birds, and mammals are also eaten. The size of the preferred prey fish varies depending on pelican species and location. For example, in Africa, the pink-backed pelican generally takes fish ranging in size from fry up to 400 g (0.9 lb) and

1440-520: Is pulled in to replace the sinking water, which in turn eventually becomes cold and salty enough to sink. Salinity distribution contributes to shape the oceanic circulation. Limnologists and chemists often define salinity in terms of mass of salt per unit volume, expressed in units of mg/L or g/L. It is implied, although often not stated, that this value applies accurately only at some reference temperature because solution volume varies with temperature. Values presented in this way are typically accurate to

1512-651: Is referred to as brine . Salinity is an ecological factor of considerable importance, influencing the types of organisms that live in a body of water. As well, salinity influences the kinds of plants that will grow either in a water body, or on land fed by a water (or by a groundwater ). A plant adapted to saline conditions is called a halophyte . A halophyte which is tolerant to residual sodium carbonate salinity are called glasswort or saltwort or barilla plants. Organisms (mostly bacteria) that can live in very salty conditions are classified as extremophiles , or halophiles specifically. An organism that can withstand

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1584-466: Is sometimes referred to as chlorinity. Operationally, dissolved matter is defined as that which can pass through a very fine filter (historically a filter with a pore size of 0.45 μm, but later usually 0.2 μm). Salinity can be expressed in the form of a mass fraction , i.e. the mass of the dissolved material in a unit mass of solution. Seawater typically has a mass salinity of around 35 g/kg, although lower values are typical near coasts where rivers enter

1656-423: Is the case today). Pelicans swim well with their strong legs and their webbed feet. They rub the backs of their heads on their preen glands to pick up an oily secretion, which they transfer to their plumage to waterproof it. Holding their wings only loosely against their bodies, pelicans float with relatively little of their bodies below the water surface. They dissipate excess heat by gular flutter – rippling

1728-511: Is the saltiness or amount of salt dissolved in a body of water , called saline water (see also soil salinity ). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal to ‰). Salinity is an important factor in determining many aspects of the chemistry of natural waters and of biological processes within it, and is a thermodynamic state variable that, along with temperature and pressure , governs physical characteristics like

1800-569: Is to estimate the value of various aspects of a wetland should not ignored. Environmental conditions at the wetlands vary throughout the year. In the fall and winter, rains in the Zagros Mountains send water flooding through an intricate series of shallow lagoons and marshes. Many of these areas dry out during the summer months. This Iran location article is a stub . You can help Misplaced Pages by expanding it . Pelican 8, see text Pelicans (genus Pelecanus ) are

1872-470: Is usually related to the sum of masses of a subset of these dissolved chemical constituents (so-called solution salinity ), rather than to the unknown mass of salts that gave rise to this composition (an exception is when artificial seawater is created). For many purposes this sum can be limited to a set of eight major ions in natural waters, although for seawater at highest precision an additional seven minor ions are also included. The major ions dominate

1944-475: The Luberon in southeastern France, and is remarkably similar to modern forms. Its beak is almost complete and is morphologically identical to that of present-day pelicans, showing that this advanced feeding apparatus was already in existence at the time. An Early Miocene fossil has been named Miopelecanus gracilis on the basis of certain features originally considered unique, but later thought to lie within

2016-549: The Old World and spread into the Americas; this is reflected in the relationships within the genus as the eight species divide into Old World and New World lineages. This hypothesis is supported by fossil evidence from the oldest pelican taxa. Pelicans will frequent inland waterways but are most known for residing along maritime and coastal zones, where they feed principally on fish in their large throat pouches, diving into

2088-529: The density and heat capacity of the water. A contour line of constant salinity is called an isohaline , or sometimes isohale . Salinity in rivers, lakes, and the ocean is conceptually simple, but technically challenging to define and measure precisely. Conceptually the salinity is the quantity of dissolved salt content of the water. Salts are compounds like sodium chloride , magnesium sulfate , potassium nitrate , and sodium bicarbonate which dissolve into ions. The concentration of dissolved chloride ions

2160-564: The hydrography is such that a possible cause of reduced circulation is the production of stratified oceans. In such cases, it is more difficult to subduct water through the thermohaline circulation. Not only is salinity a driver of ocean circulation, but changes in ocean circulation also affect salinity, particularly in the subpolar North Atlantic where from 1990 to 2010 increased contributions of Greenland meltwater were counteracted by increased northward transport of salty Atlantic waters. However, North Atlantic waters have become fresher since

2232-481: The shoebill and hamerkop storks (although these two birds are not actually true 'storks'), and are placed in the order Pelecaniformes . Ibises , spoonbills , herons , and bitterns have been classified in the same order. Fossil evidence of pelicans dates back at least 36 million years to the remains of a tibiotarsus recovered from late Eocene strata of Egypt that bears striking similarity to modern species of pelican. They are thought to have evolved in

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2304-413: The world's ocean circulation , where density changes due to both salinity changes and temperature changes at the surface of the ocean produce changes in buoyancy, which cause the sinking and rising of water masses. Changes in the salinity of the oceans are thought to contribute to global changes in carbon dioxide as more saline waters are less soluble to carbon dioxide. In addition, during glacial periods,

2376-408: The 1980s. Titration with silver nitrate could be used to determine the concentration of halide ions (mainly chlorine and bromine ) to give a chlorinity . The chlorinity was then multiplied by a factor to account for all other constituents. The resulting 'Knudsen salinities' are expressed in units of parts per thousand (ppt or ‰ ). The use of electrical conductivity measurements to estimate

2448-697: The American state of Utah 's Great Salt Lake , for example, some 600 miles (965 km) from the nearest coastline (the Pacific West Coast). They have also been seen hundreds of miles inland in North America, having flown northwards along the Mississippi River and other large waterways. Long thought to be related to frigatebirds , cormorants , tropicbirds , and gannets and boobies , pelicans instead are most closely related to

2520-464: The Australian white pelican was their next-closest relative. The great white pelican also belonged to this lineage, but was the first to diverge from the common ancestor of the other four species. This finding suggests that pelicans evolved in the Old World and spread into the Americas, and that preference for tree- or ground-nesting is more related to size than genetics. The fossil record shows that

2592-623: The abdomen, where surface protuberances may be caused by viscera changing size and position) to enable the overlying feathers to form more effective heat insulation and also to enable feathers to be held in position for good aerodynamics. Modern pelicans are found on all continents except Antarctica. They primarily inhabit warm regions, although breeding ranges extend to latitudes of 45° South (Australian pelicans in Tasmania ) and 60° North (American white pelicans in western Canada). Birds of inland and coastal waters, they are absent from polar regions,

2664-432: The airways of the respiratory system, and the pelican can keep its air sacs inflated by closing its glottis , but how air sacs are inflated is not clear. The air sacs serve to keep the pelican remarkably buoyant in the water and may also cushion the impact of the pelican's body on the water surface when they dive from flight into water to catch fish. Superficial air sacs may also help to round body contours (especially over

2736-457: The breeding season. The eight living pelican species have a patchy, seasonally-dependent yet global distribution, ranging latitudinally from the tropics to the temperate zone . Pelicans are absent from interior Amazonian South America, from polar regions and the open ocean; at least one species is known to migrate to the inland desert of Australia 's Red Centre , after heavy rains create temporary lakes. White pelicans are also observed at

2808-528: The brown and Peruvian pelicans. The bills, pouches, and bare facial skin of all species become brighter before breeding season commences. The throat pouch of the Californian subspecies of the brown pelican turns bright red, and fades to yellow after the eggs are laid, while the throat pouch of the Peruvian pelican turns blue. The American white pelican grows a prominent knob on its bill that is shed once females have laid eggs. The plumage of immature pelicans

2880-417: The composition of seawater. They can also be determined by making direct density measurements. A sample of seawater from most locations with a chlorinity of 19.37 ppt will have a Knudsen salinity of 35.00 ppt, a PSS-78 practical salinity of about 35.0, and a TEOS-10 absolute salinity of about 35.2 g/kg. The electrical conductivity of this water at a temperature of 15 °C is 42.9 mS/cm. On

2952-519: The deep ocean, oceanic islands (except the Galapagos), and inland South America, as well as from the eastern coast of South America from the mouth of the Amazon River southwards. Subfossil bones have been recovered from as far south as New Zealand's South Island , although their scarcity and isolated occurrence suggests that these remains may have merely been vagrants from Australia (much as

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3024-632: The diet of this pelican in South Africa, including Cape gannet chicks on Malgas Island as well as crowned cormorants , kelp gulls , greater crested terns , and African penguins on Dassen Island and elsewhere. The Australian pelican, which is particularly willing to take a wide range of prey items, has been recorded feeding on young Australian white ibis , and young and adult grey teals and silver gulls . Brown pelicans have been reported preying on young common murres in California and

3096-463: The distinguishing characteristics as a straight bill hooked at the tip, linear nostrils, a bare face, and fully webbed feet. This early definition included frigatebirds, cormorants, and sulids , as well as pelicans. The family Pelecanidae was introduced (as Pelicanea) by the French polymath Constantine Samuel Rafinesque in 1815. Pelicans give their name to the Pelecaniformes, an order which has

3168-568: The economic dependence and income generated from this wetland is immense, most of values are either ignored or underestimated in policy related decisions. Given the diversity of social, economic, and environmental benefits that derive from the Shadegan International Wetland, strong opinion exists that people, especially those living around the wetland, are dependent on wetland and gain long-term benefit from this ecosystem. Therefore, one major role of wetland management which

3240-997: The eggs and nestlings of cattle egrets and nestling great egrets in Baja California , Mexico. Peruvian pelicans in Chile have been recorded feeding on nestlings of imperial shags , juvenile Peruvian diving petrels , and grey gulls . Cannibalism of chicks of their own species is known from the Australian, brown, and Peruvian pelicans. Non-native great white pelicans have been observed swallowing city pigeons in St. James's Park in London, England. Globally, pelican populations are adversely affected by these main factors: declining supplies of fish through overfishing or water pollution, destruction of habitat, direct effects of human activity such as disturbance at nesting colonies, hunting and culling, entanglement in fishing lines and hooks, and

3312-491: The form of silicic acid , which usually appears as a neutral molecule in the pH range of most natural waters, may also be included for some purposes (e.g., when salinity/density relationships are being investigated). The term 'salinity' is, for oceanographers, usually associated with one of a set of specific measurement techniques. As the dominant techniques evolve, so do different descriptions of salinity. Salinities were largely measured using titration -based techniques before

3384-460: The global population of the brown pelican at 300,000. Numbers of brown pelican plummeted in the 1950s and 1960s, largely as a consequence of environmental DDT pollution, and the species was listed as endangered in the US in 1970. With restrictions on DDT use in the US from 1972, its population has recovered, and it was delisted in 2009. The Peruvian pelican is listed as near threatened because, although

3456-411: The global scale, it is extremely likely that human-caused climate change has contributed to observed surface and subsurface salinity changes since the 1950s, and projections of surface salinity changes throughout the 21st century indicate that fresh ocean regions will continue to get fresher and salty regions will continue to get saltier. Salinity is serving as a tracer of different masses. Surface water

3528-452: The great white pelican prefers somewhat larger fish, up to 600 g (1.3 lb), but in Europe, the latter species has been recorded taking fish up to 1,850 g (4.1 lb). In deep water, white pelicans often fish alone. Nearer the shore, several encircle schools of small fish or form a line to drive them into the shallows, beating their wings on the water surface and then scooping up

3600-410: The gullet head-first. A gull will sometimes stand on the pelican's head, peck it to distraction, and grab a fish from the open bill. Pelicans in their turn sometimes snatch prey from other waterbirds. The brown pelican usually plunge-dives head-first for its prey, from a height as great as 10–20 m (33–66 ft), especially for anchovies and menhaden . The only other pelican to feed using

3672-421: The inorganic composition of most (but by no means all) natural waters. Exceptions include some pit lakes and waters from some hydrothermal springs . The concentrations of dissolved gases like oxygen and nitrogen are not usually included in descriptions of salinity. However, carbon dioxide gas, which when dissolved is partially converted into carbonates and bicarbonates , is often included. Silicon in

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3744-412: The ionic content of seawater led to the development of the scale called the practical salinity scale 1978 (PSS-78). Salinities measured using PSS-78 do not have units. The suffix psu or PSU (denoting practical salinity unit ) is sometimes added to PSS-78 measurement values. The addition of PSU as a unit after the value is "formally incorrect and strongly discouraged". In 2010 a new standard for

3816-575: The local degree of environmental predictability. Colonies of tens or hundreds, rarely thousands, of birds breed regularly on small coastal and subcoastal islands where food is seasonally or permanently available. In arid inland Australia, especially in the endorheic Lake Eyre basin , pelicans breed opportunistically in very large numbers of up to 50,000 pairs, when irregular major floods, which may be many years apart, fill ephemeral salt lakes and provide large amounts of food for several months before drying out again. In all species, copulation takes place at

3888-404: The lower bill and the flexible tongue muscles form the pouch into a basket for catching fish, and sometimes rainwater, though to not hinder the swallowing of large fish, the tongue itself is tiny. They have a long neck and short stout legs with large, fully webbed feet. Although they are among the heaviest of flying birds, they are relatively light for their apparent bulk because of air pockets in

3960-409: The measured conductivity at 5 °C might only be in the range of 50–80 μS/cm. Direct density measurements are also used to estimate salinities, particularly in highly saline lakes . Sometimes density at a specific temperature is used as a proxy for salinity. At other times an empirical salinity/density relationship developed for a particular body of water is used to estimate the salinity of samples from

4032-429: The nest site; it begins shortly after pairing and continues for 3–10 days before egg-laying. The male brings the nesting material, in ground-nesting species (which may not build a nest) sometimes in the pouch, and in tree-nesting species crosswise in the bill. The female then heaps the material up to form a simple structure. The eggs are oval, white, and coarsely textured. All species normally lay at least two eggs;

4104-422: The ocean. Rivers and lakes can have a wide range of salinities, from less than 0.01 g/kg to a few g/kg, although there are many places where higher salinities are found. The Dead Sea has a salinity of more than 200 g/kg. Precipitation typically has a TDS of 20 mg/kg or less. Whatever pore size is used in the definition, the resulting salinity value of a given sample of natural water will not vary by more than

4176-491: The order of 1%. Limnologists also use electrical conductivity , or "reference conductivity", as a proxy for salinity. This measurement may be corrected for temperature effects, and is usually expressed in units of μS/cm . A river or lake water with a salinity of around 70 mg/L will typically have a specific conductivity at 25 °C of between 80 and 130 μS/cm. The actual ratio depends on the ions present. The actual conductivity usually changes by about 2% per degree Celsius, so

4248-499: The others by placement in the subgenus Leptopelecanus but in fact species with both sorts of appearance and nesting behavior are found in either. DNA sequencing of both mitochondrial and nuclear genes yielded quite different relationships; the three New World pelicans formed one lineage, with the American white pelican sister to the two brown pelicans, and the five Old World species the other. The Dalmatian, pink-backed, and spot-billed were all closely related to one another, while

4320-626: The pelican lineage has existed for at least 36 million years; the oldest known pelican fossil was assigned to Eopelecanus aegyptiacus and was found in late Eocene (middle to late part of the early Priabonian stage/age) deposits of the Birket Qarun Formation within the Wadi Al-Hitan World Heritage Site in Egypt. A more complete fossil pelican of early Oligocene age is known from deposits at

4392-586: The population is estimated by BirdLife International to exceed 500,000 mature individuals, and is possibly increasing, it has been much higher in the past. It declined dramatically during the 1998 El Niño event and could experience similar declines in the future. Conservation needs include regular monitoring throughout the range to determine population trends, particularly after El Niño years, restricting human access to important breeding colonies, and assessing interactions with fisheries. The spot-billed pelican has an estimated population between 13,000 and 18,000 and

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4464-568: The presence of pollutants such as DDT and endrin . Most species' populations are more or less stable, although three are classified by the IUCN as being at risk. All species breed readily in zoos, which is potentially useful for conservation management. The combined population of brown and Peruvian pelicans is estimated at 650,000 birds, with around 250,000 in the United States and Caribbean, and 400,000 in Peru. The National Audubon Society estimates

4536-429: The prey. Although all pelican species may feed in groups or alone, the Dalmatian, pink-backed, and spot-billed pelicans are the only ones to prefer solitary feeding. When fishing in groups, all pelican species have been known to work together to catch their prey, and Dalmatian pelicans may even cooperate with great cormorants . Large fish are caught with the bill-tip, then tossed up in the air to be caught and slid into

4608-598: The properties of seawater called the thermodynamic equation of seawater 2010 ( TEOS-10 ) was introduced, advocating absolute salinity as a replacement for practical salinity, and conservative temperature as a replacement for potential temperature . This standard includes a new scale called the reference composition salinity scale . Absolute salinities on this scale are expressed as a mass fraction, in grams per kilogram of solution. Salinities on this scale are determined by combining electrical conductivity measurements with other information that can account for regional changes in

4680-478: The range of interspecific variation in Pelecanus . The Late Eocene Protopelicanus may be a pelecaniform or suliform – or a similar aquatic bird such as a pseudotooth ( Pelagornithidae ), but is not generally considered a pelecanid . The supposed Miocene pelican Liptornis from Patagonia is a nomen dubium (of doubtful validity), being based on fragments providing insufficient evidence to support

4752-735: The reason is not clearly known, but a common belief is that it is to draw attention to itself and away from any siblings who are waiting to be fed. Parents of ground-nesting species sometimes drag older young around roughly by the head before feeding them. From about 25 days old, the young of these species gather in "pods" or " crèches " of up to 100 birds in which parents recognise and feed only their own offspring. By 6–8 weeks they wander around, occasionally swimming, and may practise communal feeding. Young of all species fledge 10–12 weeks after hatching. They may remain with their parents afterwards, but are now seldom or never fed. They are mature at three or four years old. Overall breeding success

4824-650: The right, modified from Por (1972), follows the "Venice system" (1959). In contrast to homoiohaline environments are certain poikilohaline environments (which may also be thalassic ) in which the salinity variation is biologically significant. Poikilohaline water salinities may range anywhere from 0.5 to greater than 300 ‰. The important characteristic is that these waters tend to vary in salinity over some biologically meaningful range seasonally or on some other roughly comparable time scale. Put simply, these are bodies of water with quite variable salinity. Highly saline water, from which salts crystallize (or are about to),

4896-1492: The shoebill and the hamerkop form a sister group to the pelicans, though some doubt exists as to the exact relationships among the three lineages. The oldest known record of Pelicans is a right tibiotarsus very similar to those of modern species from the Birket Qarun Formation in the Wadi El Hitan in Egypt, dating to the late Eocene ( Priabonian ), referred to the genus Eopelecanus . P. rufescens P. philippensis P. crispus P. conspicillatus P. onocrotalus P. occidentalis P. thagus P. erythrorhynchos Suliformes Herons (Ardeidae) Ibises and spoonbills (Threskiornithidae) Hamerkop ( Scopus umbretta ) Shoebill ( Balaeniceps rex ) Pelicans ( Pelecanus ) Cladogram based on Hackett et al. (2008). The eight living pelican species were traditionally divided into two groups, one containing four ground-nesters with mainly white adult plumage ( Australian , Dalmatian , great white , and American white pelicans ), and one containing four grey- or brown-plumaged species which nest preferentially either in trees ( pink-backed , spot-billed and brown pelicans ), or on sea rocks ( Peruvian pelican ). The largely marine brown and Peruvian pelicans, formerly considered conspecific , are sometimes separated from

4968-487: The skeleton and beneath the skin, enabling them to float high in the water. The tail is short and square. The wings are long and broad, suitably shaped for soaring and gliding flight, and have the unusually large number of 30 to 35 secondary flight feathers . Males are generally larger than females and have longer bills. The smallest species is the brown pelican, small individuals of which can be no more than 2.75 kg (6.1 lb) and 1.06 m (3.5 ft) long, with

5040-568: The skin of the throat and pouch with the bill open to promote evaporative cooling . They roost and loaf communally on beaches, sandbanks, and in shallow water. A fibrous layer deep in the breast muscles can hold the wings rigidly horizontal for gliding and soaring. Thus, they use thermals for soaring to heights of 3000 m (10,000 ft) or more, combined both with gliding and with flapping flight in V formation , to commute distances up to 150 km (93 mi) to feeding areas. Pelicans also fly low (or "skim") over stretches of water, using

5112-512: The usual clutch size is one to three, rarely up to six. Both sexes incubate with the eggs on top of or below the feet; they may display when changing shifts. Incubation takes 30–36 days; hatching success for undisturbed pairs can be as high as 95%, but because of sibling competition or siblicide , in the wild, usually all but one nestling dies within the first few weeks (later in the pink-backed and spot-billed species). Both parents feed their young. Small chicks are fed by regurgitation ; after about

5184-740: The water and catching them at/near the water's surface. They can adapt to varying degrees of water salinity , from freshwater and brackish to—most commonly—seawater. They are gregarious birds, travelling in flocks, hunting cooperatively , and breeding colonially . Four white-plumaged species tend to nest on the ground, and four brown or grey-plumaged species nest mainly in trees. The relationship between pelicans and people has often been contentious. The birds have been persecuted because of their perceived competition with commercial and recreational fishing. Their populations have fallen through habitat destruction , disturbance, and environmental pollution, and three species are of conservation concern. They also have

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