A grebe is a member of the order Podicipediformes and the only type of bird associated with this order. Grebes are a distributed order of freshwater diving birds, some of which visit the sea when migrating and in winter; this order contains only a single family, the Podicipedidae, containing 22 species in six extant genera. Grebes are small to medium-large in size, have lobed toes, are excellent swimmers and divers. Although they can run for a short distance, they are prone to falling over, since they have their feet placed far back on the body. Grebes have narrow wings, some species are reluctant to fly, they respond to danger by diving rather than flying, are in any case much less wary than ducks. Extant species range in size from the least grebe, at 120 grams and 23.5 cm, to the great grebe, at 1.7 kg and 71 cm. The North American and Eurasian species are all, of necessity, migratory over much or all of their ranges, those species that winter at sea are seen in flight; the small freshwater pied-billed grebe of North America has occurred as a transatlantic vagrant to Europe on more than 30 occasions.
Bills vary from short and thick to long and pointed, depending on the diet, which ranges from fish to freshwater insects and crustaceans. The feet are always large, with broad lobes on the toes and small webs connecting the front three toes; the hind toe has a small lobe. Recent experimental work has shown. Curiously, the same mechanism evolved independently in the extinct Cretaceous-age Hesperornithiformes, which are unrelated birds. Grebes have unusual plumage, it is dense and waterproof, on the underside the feathers are at right-angles to the skin, sticking straight out to begin with and curling at the tip. By pressing their feathers against the body, grebes can adjust their buoyancy, they swim low in the water with just the head and neck exposed. They swim by spreading out the feet and bring them inward with the webbing expanded to produce the forward thrust in much the same way as frogs. In the non-breeding season, grebes are plain-coloured in dark whites. However, most have ornate and distinctive breeding plumages developing chestnut markings on the head area, perform elaborate display rituals.
The young those of the genus Podiceps, are striped and retain some of their juvenile plumage after reaching full size. In the breeding season, they mate at freshwater lakes and ponds, but some species spend their non-breeding season along seacoasts; when preening, grebes eat their own feathers, feed them to their young. The function of this behaviour is uncertain but it is believed to assist with pellet formation, to reduce their vulnerability to gastric parasites. Grebes make floating nests of plant material concealed among reeds on the surface of the water; the young are precocial, able to swim from birth. The grebes are a radically distinct group of birds. Accordingly, they were at first believed to be related to the loons, which are foot-propelled diving birds, both families were once classified together under the order Colymbiformes. However, as as the 1930s, this was determined to be an example of convergent evolution by the strong selective forces encountered by unrelated birds sharing the same lifestyle at different times and in different habitat.
Grebes and loons are now separately classified orders of Podicipediformes and Gaviiformes, respectively. The cladistics vs. phenetics debate of the mid-20th century revived scientific interest in generalizing comparisons. As a consequence, the discredited grebe-loon link was discussed again; this went as far as proposing monophyly for grebes and the toothed Hesperornithiformes. In retrospect, the scientific value of the debate lies more in providing examples that a cladistic methodology is not incompatible with an overall phenetical scientific doctrine, that thus because some study "uses cladistics", it does not guarantee superior results. Molecular studies such as DNA-DNA hybridization and sequence analyses fail to resolve the relationships of grebes properly due to insufficient resolution in the former and long-branch attraction in the latter. Still – because of this – they do confirm that these birds form a ancient evolutionary lineage, they support the non-relatedness of loons and grebes.
The most comprehensive study of bird phylogenomics, published in 2014, found that grebes and flamingos are members of Columbea, a clade that includes doves and mesites. Recent molecular studies have suggested a relation with flamingos while morphological evidence strongly supports a relationship between flamingos and grebes, they hold at least eleven morphological traits in common. Many of these characteristics have been identified in flamingos, but not in grebes; the fossil Palaelodids can be considered evolutionarily, ecologically, intermediate between flamingos and grebes. For the grebe-flamingo clade, the taxon Mirandornithes has been proposed. Alternatively, they could be placed with Phoenocopteriformes taking priority; the fossil record of grebes is incomplete. The enigmatic w
The Junín grebe known as Junin flightless grebe or puna grebe, is a grebe found only on Lake Junin in the highlands of Junín, west-central Peru. The grebe breeds in bays and channels around the edge of the Lake, within 8–75 m of reed beds, entering the reeds only for nesting or roosting; when not breeding, Junin grebe prefer open water. The current population is estimated at less than 250; the scientific name commemorates the Polish zoologist Władysław Taczanowski, author of Ornithology of Peru. Another endangered species, the Junin rail, is restricted to the same lake. With a size of 35 cm, the Junin grebe has a dark grey crown extending down the back of its neck to a black back, it has white lower parts of the face and underparts, with a narrow grey bill. The most striking feature is its bright red eyes. On the side of the head of adults there are silvery grey feathers, which are absent on non-breeding adults and juveniles, its calls include melodic whistles doo’ ith, a longer phooee-th when trying to attract a mate.
Courtship involves two grebes facing breast to breast and turning their head from side to side, called ‘head-shaking’. The nests of Junin grebes are built in reed beds around the border of Lake Junin, a typical clutch size is two eggs, laid in December or January. In years when the water level of the lake is low, no young are raised; the Junin grebe’s exceptional diving skills allows it to feed on small fish and invertebrates. They can be seen feeding and diving in small groups. Junin grebes are endemic to Lake Junin, in west-central Peru; the lake covers 140 km2 and at its deepest is 10m deep, although most of the lake is less than 5m deep. Around the borders of the lake are substantial reed marshes, where the grebes nest and roost. Lake Junin has been classed as a national reserve since 1974, which has restricted the amount of fishing and hunting that can take place there. More in 2002, the Peruvian government made an emergency law to place harsher restrictions on water extraction and provisions for cleaning of the lake, but so far this has not been properly enforced.
Attempts have been made to translocate the grebes to a lake just north of Lake Junin, however gill nets used to catch rainbow trout in this lake meant it was unsuccessful. Further studies are being carried out to locate other lakes that the Junin grebe could be translocated to. Large fluctuations in water levels, caused by a nearby hydroelectric plant, water pollution from mining activities have caused the population of grebes to fall from 1000 in 1961 to around 200 in 2007. Contamination of the lake from mining waste products kills the small fish that are the Junin grebes main source of food; the hydroelectric plant can cause the water level to drop below 5m, which prevents the birds from raising chicks, can cause damage to the bordering reed marshes. A local organisation, Asociaciόn Ecosistemas Andinos, is working to educate local people about the Junin grebe and the Junin rail –, endemic to the lake; the aim is to raise awareness of the issue, get the mining and hydroelectric plant organisations to understand the issue.
BirdLife species factsheet for Podiceps taczanowskii "Podiceps taczanowskii". Avibase. "Junin flightless grebe media". Internet Bird Collection. Junin Grebe species account at Neotropical Birds Interactive range map of Podiceps taczanowskii at IUCN Red List maps Audio recordings of Junin Grebe on Xeno-canto
The Atitlán grebe known as giant grebe, giant pied-billed grebe, or poc, is an extinct water bird, a relative of the pied-billed grebe. It was endemic at the Lago de Atitlán in Guatemala at an altitude of 1700 m asl, it was described in 1929 by Ludlow Griscom based on a specimen collected in 1926 and had been overlooked in the past. American ecologist Anne LaBastille observed the decline of this species over a period of 25 years, it was declared extinct by 1990. The Atitlán grebe reached a length of about 46–50 cm; the call and appearance were similar to the much smaller pied-billed grebe. The bill was large and pied but the color varied from white in the spring to brown in other seasons; the plumage was dark brown with white-flecked flanks and grey on the ears. The underparts were dark grey flecked with white; the head was black and the neck was glossy flecked with dark brown in the spring and white in the winter. The legs were slaty grey; the bill had a bold black vertical band in the middle. The irises were brown.
It was flightless. They laid a clutch of 4 to 5 white eggs. Both parents shared the rearing of the hatchlings; the decline of the Atitlán grebe began in 1958 and again in 1960 after smallmouth bass and largemouth bass were introduced into Lake Atitlán. These invasive species reduced the crabs and fish which the grebes depended on for food and the fish killed the grebe chicks; the population of the Atitlán grebe declined from 200 individuals in 1960 to 80 in 1965. Thanks to the conservation efforts of Anne LaBastille, in 1966 a refuge was established where this species was able to rebound; the population recovered to 210 in 1973. After the 1976 Guatemala earthquake, the lake bed fractured. An underwater drain led to a fall of the water level and to a further severe decrease of the number of grebes. In 1983 only 32 individuals were left, of which the largest part were hybrids with the pied-billed grebe; the last two birds were seen in 1989, after they disappeared the Atitlán grebe was declared extinct.
Alaotra grebe extinct since the late 1980s for analogous reasons. Colombian grebe Flannery, Tim & Schouten, Peter. A Gap in Nature: Discovering the World's Extinct Animals, Atlantic Monthly Press, New York. ISBN 0-87113-797-6. Errol Fuller. Extinct Birds, ISBN 0-8160-1833-2 Anne LaBastille. Mama Poc: An Ecologist's Account of the Extinction of a Species, W. W. Norton & Company, ISBN 0-393-02830-5 Status of the Endemic Atitlan Grebe of Guatemala: Is it extinct
Tachybaptus is a genus of small members of the grebe family birds. The genus name is from Ancient Greek takhus "fast" and bapto "to sink under", it has representatives over much including the tropics. These grebes breed in small colonies in vegetated areas of freshwater lakes, they may move to more open or coastal waters when not breeding, birds in those areas where the waters freeze may be migratory. Like all grebes, they nest on the water's edge, since the legs are set far back and they cannot walk well; the striped young are sometimes carried on the adult's back. These small grebes are excellent swimmers and divers, pursue their fish prey underwater; the name Tachybaptus means "quick diving". The sexes are similar and short-billed with a “powder puff” rear end. Adults have loud breeding calls. In winter, they are white; the five Old World species are related to each and at least three have interbred. Unlike these, the least grebe lacks chestnut colouring on the neck, has been placed in at least three other genera.
Little grebe, Tachybaptus ruficollis Tricolored grebe, Tachybaptus tricolor Australasian grebe Tachybaptus novaehollandiae Madagascar grebe, Tachybaptus pelzelnii Alaotra grebe, Tachybaptus rufolavatus - Extinct Least grebe, Tachybaptus dominicus Olgilvie and Rose, Grebes of the World ISBN 1-872842-03-8 Harrison, Peter Seabirds: An Identification Guide ISBN 0-7470-1410-8
Europe is a continent located in the Northern Hemisphere and in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west and the Mediterranean Sea to the south, it comprises the westernmost part of Eurasia. Since around 1850, Europe is most considered to be separated from Asia by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas and the waterways of the Turkish Straits. Although the term "continent" implies physical geography, the land border is somewhat arbitrary and has been redefined several times since its first conception in classical antiquity; the division of Eurasia into two continents reflects East-West cultural and ethnic differences which vary on a spectrum rather than with a sharp dividing line. The geographic border does not follow political boundaries, with Turkey and Kazakhstan being transcontinental countries. A strict application of the Caucasus Mountains boundary places two comparatively small countries and Georgia, in both continents.
Europe covers 2 % of the Earth's surface. Politically, Europe is divided into about fifty sovereign states of which the Russian Federation is the largest and most populous, spanning 39% of the continent and comprising 15% of its population. Europe had a total population of about 741 million as of 2016; the European climate is affected by warm Atlantic currents that temper winters and summers on much of the continent at latitudes along which the climate in Asia and North America is severe. Further from the sea, seasonal differences are more noticeable than close to the coast. Europe, in particular ancient Greece, was the birthplace of Western civilization; the fall of the Western Roman Empire in 476 AD and the subsequent Migration Period marked the end of ancient history and the beginning of the Middle Ages. Renaissance humanism, exploration and science led to the modern era. Since the Age of Discovery started by Portugal and Spain, Europe played a predominant role in global affairs. Between the 16th and 20th centuries, European powers controlled at various times the Americas all of Africa and Oceania and the majority of Asia.
The Age of Enlightenment, the subsequent French Revolution and the Napoleonic Wars shaped the continent culturally and economically from the end of the 17th century until the first half of the 19th century. The Industrial Revolution, which began in Great Britain at the end of the 18th century, gave rise to radical economic and social change in Western Europe and the wider world. Both world wars took place for the most part in Europe, contributing to a decline in Western European dominance in world affairs by the mid-20th century as the Soviet Union and the United States took prominence. During the Cold War, Europe was divided along the Iron Curtain between NATO in the West and the Warsaw Pact in the East, until the revolutions of 1989 and fall of the Berlin Wall. In 1949 the Council of Europe was founded, following a speech by Sir Winston Churchill, with the idea of unifying Europe to achieve common goals, it includes all European states except for Belarus and Vatican City. Further European integration by some states led to the formation of the European Union, a separate political entity that lies between a confederation and a federation.
The EU originated in Western Europe but has been expanding eastward since the fall of the Soviet Union in 1991. The currency of most countries of the European Union, the euro, is the most used among Europeans. In classical Greek mythology, Europa was a Phoenician princess; the word Europe is derived from her name. The name contains the elements εὐρύς, "wide, broad" and ὤψ "eye, countenance", hence their composite Eurṓpē would mean "wide-gazing" or "broad of aspect". Broad has been an epithet of Earth herself in the reconstructed Proto-Indo-European religion and the poetry devoted to it. There have been attempts to connect Eurṓpē to a Semitic term for "west", this being either Akkadian erebu meaning "to go down, set" or Phoenician'ereb "evening, west", at the origin of Arabic Maghreb and Hebrew ma'arav. Michael A. Barry, professor in Princeton University's Near Eastern Studies Department, finds the mention of the word Ereb on an Assyrian stele with the meaning of "night, sunset", in opposition to Asu " sunrise", i.e. Asia.
The same naming motive according to "cartographic convention" appears in Greek Ἀνατολή. Martin Litchfield West stated that "phonologically, the match between Europa's name and any form of the Semitic word is poor." Next to these hypotheses there is a Proto-Indo-European root *h1regʷos, meaning "darkness", which produced Greek Erebus. Most major world languages use words derived from Europa to refer to the continent. Chinese, for example, uses the word Ōuzhōu. In some Turkic languages the Persian name Frangistan is used casually in referring to much of Europe, besides official names such as Avrupa or Evropa; the prevalent definition of Europe as a geographical term has been in use since the mid-19th century. Europe is taken to be bounded by large bodies of water
North America is a continent within the Northern Hemisphere and all within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, to the southeast by South America and the Caribbean Sea. North America covers an area of about 24,709,000 square kilometers, about 16.5% of the earth's land area and about 4.8% of its total surface. North America is the third largest continent by area, following Asia and Africa, the fourth by population after Asia and Europe. In 2013, its population was estimated at nearly 579 million people in 23 independent states, or about 7.5% of the world's population, if nearby islands are included. North America was reached by its first human populations during the last glacial period, via crossing the Bering land bridge 40,000 to 17,000 years ago; the so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago. The Classic stage spans the 6th to 13th centuries.
The Pre-Columbian era ended in 1492, the transatlantic migrations—the arrival of European settlers during the Age of Discovery and the Early Modern period. Present-day cultural and ethnic patterns reflect interactions between European colonists, indigenous peoples, African slaves and their descendants. Owing to the European colonization of the Americas, most North Americans speak English, Spanish or French, their culture reflects Western traditions; the Americas are accepted as having been named after the Italian explorer Amerigo Vespucci by the German cartographers Martin Waldseemüller and Matthias Ringmann. Vespucci, who explored South America between 1497 and 1502, was the first European to suggest that the Americas were not the East Indies, but a different landmass unknown by Europeans. In 1507, Waldseemüller produced a world map, in which he placed the word "America" on the continent of South America, in the middle of what is today Brazil, he explained the rationale for the name in the accompanying book Cosmographiae Introductio:... ab Americo inventore... quasi Americi terram sive Americam.
For Waldseemüller, no one should object to the naming of the land after its discoverer. He used the Latinized version of Vespucci's name, but in its feminine form "America", following the examples of "Europa", "Asia" and "Africa". Other mapmakers extended the name America to the northern continent, In 1538, Gerard Mercator used America on his map of the world for all the Western Hemisphere; some argue that because the convention is to use the surname for naming discoveries, the derivation from "Amerigo Vespucci" could be put in question. In 1874, Thomas Belt proposed a derivation from the Amerrique mountains of Central America. Marcou corresponded with Augustus Le Plongeon, who wrote: "The name AMERICA or AMERRIQUE in the Mayan language means, a country of perpetually strong wind, or the Land of the Wind, and... the can mean... a spirit that breathes, life itself." The United Nations formally recognizes "North America" as comprising three areas: Northern America, Central America, The Caribbean.
This has been formally defined by the UN Statistics Division. The term North America maintains various definitions in accordance with context. In Canadian English, North America refers to the land mass as a whole consisting of Mexico, the United States, Canada, although it is ambiguous which other countries are included, is defined by context. In the United States of America, usage of the term may refer only to Canada and the US, sometimes includes Greenland and Mexico, as well as offshore islands. In France, Portugal, Romania and the countries of Latin America, the cognates of North America designate a subcontinent of the Americas comprising Canada, the United States, Mexico, Greenland, Saint Pierre et Miquelon, Bermuda. North America has been referred to by other names. Spanish North America was referred to as Northern America, this was the first official name given to Mexico. Geographically the North American continent has many subregions; these include cultural and geographic regions. Economic regions included those formed by trade blocs, such as the North American Trade Agreement bloc and Central American Trade Agreement.
Linguistically and culturally, the continent could be divided into Latin America. Anglo-America includes most of Northern America and Caribbean islands with English-speaking populations; the southern North American continent is composed of two regions. These are the Caribbean; the north of the continent maintains recognized regions as well. In contrast to the common definition of "North America", which encompasses the whole continent, the term "North America" is sometimes used to refer only to Mexico, the United States, Greenland; the term Northern America refers to the northern-most countries and territories of North America: the United States, Bermuda, St. Pierre and Miquelon and Greenland. Although the term does not refer to a unifie