The western grebe is a species in the grebe family of water birds. Folk names include "dabchick", "swan grebe" and "swan-necked grebe". Western grebe fossils from the Late Pleistocene of SW North America were described as a distinct species, but ranked as a paleosubspecies Aechmophorus occidentalis lucasi. More recent study found them to fall within the variation now known to exist in today's birds; the western grebe is the largest North American grebe. It is 55–75 cm long, weighs 795–2,000 g and measures 79–102 cm across the wings, it is black-and-white, with a long, swan-like neck and red eyes. It is confused with Clark's grebe, which shares similar features, body size and habitat, hybrids are known. Western Grebes nest in colonies on lakes that are mixed with open water. Western Grebe nests are made of plant debris and sodden materials, the nest building begins around late April through June; the construction is continued on throughout laying and incubation. This species of waterbirds is widespread in western North America, so there is no specific place of abundance.
Its subspecies, Clark's grebe populate more of the southern part of North America Other differences are whiter flanks and paler gray backs when comparing A.o.clarkii to A.o.occidentalis. The western grebe has black around the eyes and a straight greenish-yellow bill whereas the Clark's grebe has white around the eyes and an up-turned bright yellow bill; the downy young of Western are grey. In 1858 George Newbold Lawrence recognised Podiceps occidentalis based on darker coloured specimens, P. clarkii based on three paler coloured specimens -two from California and one from Chihuahua. These two colour morphs were found to occur and interbreed together, were long regarded to be synonyms. Deignan designated the Mexican specimen as the holotype of the taxon P. clarkii in 1961. In 1963 Dickerman reinstated the taxon as Aechmophorus clarkii, which he defined as the smaller birds, both dark and pale coloured, from Mexico. In 1979 a comprehensive study by Ratti demonstrated the apparent existence of reproductive barriers between different phases of the grebes.
In 1986 Dickerman recognised the taxonomic significance of the distinctions between the dark and pale phase, classified these phases as different subspecies: A. occidentalis ssp. occidentalis, dark morph, from western Canada & United States A. occidentalis ssp. ephemeralis, Dickerman, 1986, pale morph, from western Canada & United States A. clarkii ssp. clarkii, Dickerman, 1963 - Small, pale morph, from north & central Mexico. A. clarkii ssp. transitionalis, Dickerman, 1986 - Smaller than the western grebe, dark morph, from north & central Mexico. Multiple lines of evidence suggest that the differently colored western grebes are different taxa -in a single population in which sympatric speciation somehow persists; these forms were reported to mate according to their own colors and the mixing between dark and light-faced individuals is rare. This type of assortative mating derives from possible isolating mechanisms such as differential responses to advertising calls and spatial distribution.
Each of the forms tended to stay closer to their own type, thus making their colony nesting be non-randomly distributed. By 1992 Storer & Nuechterlein were promoting another concept to the taxon A. clarkii, now regarding the pale morphs from the USA and Canada to be this taxon. Western grebes nest in colonies of hundreds on large inland lakes, sometimes using coastal marshes, in western North America, it has a spectacular courtship display. Northern birds migrate west to coastal ocean in winter. During the breeding season, the birds advertise themselves through ceremonies. Rushing Ceremony, which can be called as water dance, race or run, is a ceremony, the most frequent display to form a pair-bond; this is performed in pairs of either one female. One of two individuals initiates Rushing, the paired individual follows and performs in synchrony; the birds lift their wings stiffly to the side and run in an upright position with its head held forward and neck curved. The males seem to perform the rushing together to attract attentions of females, when one of two males attracts a female from his rushing behavior, a competition arises between males to get the female.
One out of two withdraw and the "winning" male mates with the female by performing Rushing together and continue to perform Weed Ceremony. Weed Ceremony precedes the acts of mating and nest building, it is done after the pair is formed, the ceremony begins as the mates bob their heads in water. They dive in place and come back up to surface while holding weed on their beaks; this ceremony is continued until one of the pair flips away its weeds and drops to a normal position in water. They continue their mating with Greeting Ceremony. Greeting ceremony is similar to the form of rushing ceremony and involves dip-shaking, bob-shaking, bob-preening and arch-clucking. Dip-shaking consists of dipping the head in the water and raising it up while waggling the bill side to side; this involves a low neck posture and conspicuous water splash. These breeding dances are known to be the most elaborated dances in the water b
A fossil is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, petrified wood, coal, DNA remnants; the totality of fossils is known as the fossil record. Paleontology is the study of fossils: their age, method of formation, evolutionary significance. Specimens are considered to be fossils if they are over 10,000 years old; the oldest fossils are around 3.48 billion years old to 4.1 billion years old. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils; the development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ages of rocks and the fossils they host. There are many processes that lead to fossilization, including permineralization and molds, authigenic mineralization and recrystallization, adpression and bioimmuration.
Fossils vary in size from one-micrometre bacteria to dinosaurs and trees, many meters long and weighing many tons. A fossil preserves only a portion of the deceased organism that portion, mineralized during life, such as the bones and teeth of vertebrates, or the chitinous or calcareous exoskeletons of invertebrates. Fossils may consist of the marks left behind by the organism while it was alive, such as animal tracks or feces; these types of fossil are called trace ichnofossils, as opposed to body fossils. Some fossils are called chemofossils or biosignatures; the process of fossilization varies according to external conditions. Permineralization is a process of fossilization; the empty spaces within an organism become filled with mineral-rich groundwater. Minerals precipitate from the groundwater; this process can occur in small spaces, such as within the cell wall of a plant cell. Small scale permineralization can produce detailed fossils. For permineralization to occur, the organism must become covered by sediment soon after death, otherwise decay commences.
The degree to which the remains are decayed when covered determines the details of the fossil. Some fossils consist only of skeletal teeth; this is a form of diagenesis. In some cases, the original remains of the organism dissolve or are otherwise destroyed; the remaining organism-shaped hole in the rock is called an external mold. If this hole is filled with other minerals, it is a cast. An endocast, or internal mold, is formed when sediments or minerals fill the internal cavity of an organism, such as the inside of a bivalve or snail or the hollow of a skull; this is a special form of mold formation. If the chemistry is right, the organism can act as a nucleus for the precipitation of minerals such as siderite, resulting in a nodule forming around it. If this happens before significant decay to the organic tissue fine three-dimensional morphological detail can be preserved. Nodules from the Carboniferous Mazon Creek fossil beds of Illinois, USA, are among the best documented examples of such mineralization.
Replacement occurs. In some cases mineral replacement of the original shell occurs so and at such fine scales that microstructural features are preserved despite the total loss of original material. A shell is said to be recrystallized when the original skeletal compounds are still present but in a different crystal form, as from aragonite to calcite. Compression fossils, such as those of fossil ferns, are the result of chemical reduction of the complex organic molecules composing the organism's tissues. In this case the fossil consists of original material, albeit in a geochemically altered state; this chemical change is an expression of diagenesis. What remains is a carbonaceous film known as a phytoleim, in which case the fossil is known as a compression. However, the phytoleim is lost and all that remains is an impression of the organism in the rock—an impression fossil. In many cases, however and impressions occur together. For instance, when the rock is broken open, the phytoleim will be attached to one part, whereas the counterpart will just be an impression.
For this reason, one term covers the two modes of preservation: adpression. Because of their antiquity, an unexpected exception to the alteration of an organism's tissues by chemical reduction of the complex organic molecules during fossilization has been the discovery of soft tissue in dinosaur fossils, including blood vessels, the isolation of proteins and evidence for DNA fragments. In 2014, Mary Schweitzer and her colleagues reported the presence of iron particles associated with soft tissues recovered from dinosaur fossils. Based on various experiments that studied the interaction of iron in haemoglobin with blood vessel tissue they proposed that solution hypoxia coupled with iron chelation enhances the stability and preservation of soft tissue and provides the basis for an explanation for the unforeseen preservation of fossil soft tissues. However, a older study based on eight taxa ranging in time from the Devonian to the Jurassic found that reasonably well-preserved fibrils that represent collagen were preser
The Condor (journal)
The Condor: Ornithological Applications is a peer-reviewed weekly scientific journal covering ornithology. It is an official journal of the American Ornithological Society; the journal was first published in 1899 as the Bulletin of the Cooper Ornithological Club by a group of biologists in California. The journal's scope was regional. In 1900 the name was changed to The Condor. In 1947, the journal's subtitle was shortened to The Condor, Journal of the Cooper Ornithological Club. Editors-in-Chief: 1899-1902: Chester Barlow. An editorial board was established in 1951 to address increasing submissions to the journal. James King, of Washington State University, instituted a system for external peer review of submissions. King became editor after Alden H. Miller's death in 1965. Miller replaced Grinnell as editor in 1939. King widened the scope of the journal, by 1966, at least 40% of papers published in The Condor are written by scientists outside the United States. In Glenn Walsberg's 1993 "History of The Condor", he concluded that "several thousand people have contributed to the success and development of this journal in its 95-year history.
In 1992 alone, 653 scientists aided in its production in the roles of author, reviewer, or both."In 2013, The Condor became The Condor: Ornithological Applications, with a change of content focus to the following applied areas of ornithology: population biology, including threats to bird populations, conservation genetics and landscape ecology, ecosystem-level influences of birds, effects of habitat alteration and fragmentation, avian responses to climate change, anthropogenic effects on genetics, behavior, or physiological processes, biology of avian diseases and disease transmission by birds, birds in urban or agricultural settings and economics studies related to birds or the discipline of ornithology and cross-disciplinary studies and methodological advances in practice, evaluations of science relevant to issues in conservation and management, thematic reviews and opinion pieces In 2016, the American Ornithological Society was created from the merging of the Cooper Ornithological Society and the American Ornithologists' Union.
In 2018, the American Ornithology Society announced a partnership with Oxford University Press to publish The Condor: Ornithological Applications and The Auk: Ornithological Advances. In the prose style of the time period, the first issue's editorial sets out the focus of the journal as "its object being to represent the great West, the Cooper Ornithological Club, it is conceded that the West is rich in its possibilities of new discoveries, both in faunal forms and data regarding the life histories of many species …" The editorial comments on a newspaper story from the San Francisco Chronicle about a successful hunt by the Petaluma Sportsmen's Club: "The joint bag showed 821 bluejays and 51 hawks'of various kinds' slaughtered on the plea that'each would have destroyed at least five quail’s eggs during the next breeding season.'" The editorial added that "the Bulletin stands for bird protection, will strenuously oppose wanton slaughter at ail times regardless of its source." List of ornithology journals BioOne: The Condor.
Vol. 102 onwards. Retrieved 2017-AUG-15. SORA: The Condor. Vol. 1–102 free PDF/DejaVu fulltexts. Retrieved 2017-AUG-15; the Condor: "The Condor" Vol. 102 onwards
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
Elliott Coues was an American army surgeon, historian and author. Elliott Ladd Coues was born in Portsmouth, New Hampshire to Samuel Elliott Coues and Charlotte Haven Ladd Coues, he graduated at Columbian University, Washington, D. C. in 1861, at the Medical school of that institution in 1863. He served as a medical cadet in Washington in 1862–1863, in 1864 was appointed assistant-surgeon in the regular army, assigned to Fort Whipple, Arizona. While there was not yet any legal provision for divorce under its laws, the 1st Arizona State Legislature granted Coues an annullment of his marriage to Sarah A. Richardson. In 1872 he published his Key to North American Birds, which and rewritten in 1884 and 1901, did much to promote the systematic study of ornithology in America, he was a founding member of the American Ornithologists' Union in 1883. His work was instrumental in establishing the accepted standards of trinomial nomenclature – the taxonomic classification of subspecies – in ornithology, the whole of zoology.
During 1873–1876 Coues was attached as surgeon and naturalist to the United States Northern Boundary Commission, from 1876 to 1880 he was secretary and naturalist to the United States Geological and Geographical Survey of the Territories, the publications of which he edited. He was lecturer on anatomy in the medical school of the Columbian University from 1877 to 1882, professor of anatomy there from 1882 to 1887, he was a careful bibliographer and in his work on the Birds of the Colorado Valley he included a special section on swallows and attempted to resolve whether they migrated in winter or hibernated under lakes as was believed at the time: I have never seen anything of the sort, nor have I known one who had seen it. But I have no means of refuting the evidence, cannot refuse to recognize its validity. Nor have I aught to urge against it, beyond the degree of incredibility that attaches to exceptional and improbable allegations in general, in particular the difficulty of understanding the alleged abruptness of the transition from activity to torpor.
I cannot consider the evidence as inadmissible, must admit that the alleged facts are as well attested, according to ordinary rules of evidence, as any in ornithology. It is useless as well as unscientific to pooh-pooh the notion; the asserted facts are nearly identical with the known cases of many batrachians. They are strikingly like the known cases of many bats, they accord in general with the recognized conditions of hibernation in many mammals. He resigned from the army in 1881 to devote himself to scientific research, he was a founder of the American Ornithologists' Union, edited its organ, The Auk, several other ornithological periodicals. He died in Maryland. Grace's warbler was discovered by Elliott Coues in the Rocky Mountains in 1864, he requested that the new species be named after his 18-year-old sister, Grace Darling Coues, his request was honored when Spencer Fullerton Baird described the species scientifically in 1865. In addition to ornithology he did valuable work in mammalogy.
Odocoileus virginianus couesi, the Coues white-tailed deer is named after him. Coues began speculations in Theosophy, he was a friend of Alfred Russel Wallace and they had attended séances with the medium Pierre L. O. A. Keeler, he felt the inadequacy of formal orthodox science in dealing with the deeper problems of human life and destiny. Convinced by the principles of evolution, he believed that these principles may be capable of being applied in psychical research and he proposed to use it to explain obscure phenomena such as hypnotism and telepathy, he claimed to have witnessed levitation of objects and developed a theory to explain the phenomenon, publishing an article about his telekinetic theory of levitation in the first issue of The Metaphysical Magazine. Coues joined the Theosophical Society in July, 1884, he visited Helena Blavatsky in Europe. He founded the Gnostic Theosophical Society of Washington, in 1890 became the president of the Theosophical Society, he became critical of Blavatsky and lost interest in the Theosophical movement.
Coues wrote an attack on Blavatsky entitled "Blavatsky Unveiled!" in The Sun newspaper on July 20, 1890. The article prompted Blavatsky to file a legal suit against Coues and the newspaper but it was terminated as she passed away in 1891, he fell out with Theosophical leaders such as William Quan Judge and was expelled from the Theosophical Society in June, 1899 for "untheosophical conduct". Coues retained interest in oriental religious thought and studied Islam. Among the most important of his publications are: A Field Ornithology. Rural Bird Life of England, with Charles Dixon. Coues contributed numerous articles to the Century Dictionary, wrote for various encyclopaedias, edited: Journals of Lewis and Clark. Pike.
An estuary is a enclosed coastal body of brackish water with one or more rivers or streams flowing into it, with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments, they are subject both to marine influences—such as tides and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The mixing of sea water and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world. Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are classified according to their geomorphological features or to water-circulation patterns, they can have many different names, such as bays, lagoons, inlets, or sounds, although some of these water bodies do not meet the above definition of an estuary and may be saline.
The banks of many estuaries are amongst the most populated areas of the world, with about 60% of the world's population living along estuaries and the coast. As a result, many estuaries suffer degradation from a variety of factors including: sedimentation from soil erosion from deforestation and other poor farming practices; the word "estuary" is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus, meaning tide. There have been many definitions proposed to describe an estuary; the most accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, within which sea water is measurably diluted with freshwater derived from land drainage". However, this definition excludes a number of coastal water bodies such as coastal lagoons and brackish seas. A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff.
This broad definition includes fjords, river mouths, tidal creeks. An estuary is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides; the sea water entering the estuary streams. The pattern of dilution varies between different estuaries and depends on the volume of fresh water, the tidal range, the extent of evaporation of the water in the estuary. Drowned river valleys are known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley; this is the most common type of estuary in temperate climates. Well-studied estuaries include the Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border; the width-to-depth ratio of these estuaries is large, appearing wedge-shaped in the inner part and broadening and deepening seaward. Water depths exceed 30 m.
Examples of this type of estuary in the U. S. are the Hudson River, Chesapeake Bay, Delaware Bay along the Mid-Atlantic coast, Galveston Bay and Tampa Bay along the Gulf Coast. Bar-built estuaries are found in place where the deposition of sediment has kept pace with rising sea level so that the estuaries are shallow and separated from the sea by sand spits or barrier islands, they are common in tropical and subtropical locations. These estuaries are semi-isolated from ocean waters by barrier beaches. Formation of barrier beaches encloses the estuary, with only narrow inlets allowing contact with the ocean waters. Bar-built estuaries develop on sloping plains located along tectonically stable edges of continents and marginal sea coasts, they are extensive along the Atlantic and Gulf coasts of the U. S. in areas with active coastal deposition of sediments and where tidal ranges are less than 4 m. The barrier beaches that enclose bar-built estuaries have been developed in several ways: building up of offshore bars by wave action, in which sand from the sea floor is deposited in elongated bars parallel to the shoreline, reworking of sediment discharge from rivers by wave and wind action into beaches, overwash flats, dunes, engulfment of mainland beach ridges due to sea level rise and resulting in the breaching of the ridges and flooding of the coastal lowlands, forming shallow lagoons, elongation of barrier spits from the erosion of headlands due to the action of longshore currents, with the spits growing in the direction of the littoral drift.
Barrier beaches form in shallow water and are parallel to the shoreline, resulting in long, narrow estuaries. The average water depth is less than 5 m, exceeds 10 m. Examples of bar-built estuaries are Barnegat Bay, New Jersey. Fjords were formed where pleistocene glaciers deepened and widened existing river valleys so that they become U-shaped in cross s