The passenger pigeon or wild pigeon is an extinct species of pigeon, endemic to North America. Its common name is derived from the French word passager, meaning "passing by", due to the migratory habits of the species; the scientific name refers to its migratory characteristics. The morphologically similar mourning dove was long thought to be its closest relative, the two were at times confused, but genetic analysis has shown that the genus Patagioenas is more related to it than the Zenaida doves; the passenger pigeon was sexually dimorphic in coloration. The male was 390 to 410 mm in length gray on the upperparts, lighter on the underparts, with iridescent bronze feathers on the neck, black spots on the wings; the female was 380 to 400 mm, was duller and browner than the male overall. The juvenile was similar without iridescence, it inhabited the deciduous forests of eastern North America and was recorded elsewhere, but bred around the Great Lakes. The pigeon migrated in enormous flocks searching for food and breeding grounds, was once the most abundant bird in North America, numbering around 3 billion, up to 5 billion, “at the time of the discovery of America,” according to A. W. Schorger.
Though one genetic study concluded that the bird was not always that abundant, that the population size fluctuated over time, a more recent study found evidence that this was not the correct interpretation of the genetic data, instead concluded that the passenger pigeon population size had been stable for at least 20,000 years prior to "its 19th-century decline and eventual extinction." A fast flyer, the passenger pigeon could reach a speed of 100 km/h. The bird fed on mast, fruits and invertebrates, it practiced communal roosting and communal breeding, its extreme gregariousness may be linked with searching for food and predator satiation. Passenger pigeons were hunted by Native Americans, but hunting intensified after the arrival of Europeans in the 19th century. Pigeon meat was commercialized as cheap food, resulting in hunting on a massive scale for many decades. There were several other factors contributing to the decline and subsequent extinction of the species, including shrinking of the large breeding populations necessary for preservation of the species and widespread deforestation, which destroyed its habitat.
A slow decline between about 1800 and 1870 was followed by a rapid decline between 1870 and 1890. The last confirmed wild bird is thought to have been shot in 1901; the last captive birds were divided in three groups around the turn of the 20th century, some of which were photographed alive. Martha, thought to be the last passenger pigeon, died on September 1914, at the Cincinnati Zoo; the eradication of this species is a notable example of anthropogenic extinction. Swedish naturalist Carl Linnaeus coined the binomial name Columba macroura for both the mourning dove and the passenger pigeon in the 1758 edition of his work Systema Naturae, wherein he appears to have considered the two identical; this composite description cited accounts of these birds in two pre-Linnean books. One of these was Mark Catesby's description of the passenger pigeon, published in his 1731 to 1743 work Natural History of Carolina and the Bahama Islands, which referred to this bird as Palumbus migratorius, was accompanied by the earliest published illustration of the species.
Catesby's description was combined with the 1743 description of the mourning dove by George Edwards, who used the name C. macroura for that bird. There is nothing to suggest Linnaeus saw specimens of these birds himself, his description is thought to be derivative of these earlier accounts and their illustrations. In his 1766 edition of Systema Naturae, Linnaeus dropped the name C. macroura, instead used the name C. migratoria for the passenger pigeon, C. carolinensis for the mourning dove. In the same edition, Linnaeus named C. canadensis, based on Turtur canadensis, as used by Mathurin Jacques Brisson in 1760. Brisson's description was shown to have been based on a female passenger pigeon. In 1827 William John Swainson moved the passenger pigeon from the genus Columba to the new monotypic genus Ectopistes, due in part to the length of the wings and the wedge shape of the tail. In 1906 Outram Bangs suggested that because Linnaeus had wholly copied Catesby's text when coining C. macroura, this name should apply to the passenger pigeon, as E. macroura.
In 1918 Harry C. Oberholser suggested that C. canadensis should take precedence over C. migratoria, as it appeared on an earlier page in Linnaeus' book. In 1952 Francis Hemming proposed that the International Commission on Zoological Nomenclature secure the specific name macroura for the mourning dove, the name migratorius for the passenger pigeon, since this was the intended use by the authors on whose work Linnaeus had based his description; this was accepted by the ICZN, which used its plenary powers to designate the species for the respective names in 1955. The passenger pigeon was a member of Columbidae, its closest living relatives were long thought to be the Zenaida doves, based on morphological grounds the physically similar mourning dove. It was suggested that the mourning dove belonged to the genus Ectopistes and was listed as E. carolinensis by some authors, including Thomas Mayo Brewer. The passenger pigeon was descended from Zenaida pigeons that had adapted to the woodlands on the plains of centra
Portage or portaging is the practice of carrying water craft or cargo over land, either around an obstacle in a river, or between two bodies of water. A path where items are carried between bodies of water is called a portage. Early French explorers in New France and French Louisiana encountered many cascades; the Native Americans carried their canoes over land to avoid river obstacles. Over time, important portages were sometimes provided with canals with locks, portage railways. Primitive portaging involves carrying the vessel and its contents across the portage in multiple trips. Small canoes can be portaged by carrying them inverted over one's shoulders and the center strut may be designed in the style of a yoke to facilitate this. Voyageurs employed tump lines on their heads to carry loads on their backs. Portages can be many kilometers in length, such as the 19-kilometre Methye Portage and the 8.5-mile Grand Portage covering hilly or difficult terrain. Some portages involve little elevation change, such as the short Mavis Grind in Shetland, which crosses an isthmus.
This section deals with the heavy freight canoes used by the Canadian Voyageurs. Portage trails began as animal tracks and were improved by tramping or blazing. In a few places iron-plated wooden rails were laid to take a handcart. Used routes sometimes evolved into roads when sledges, rollers or oxen were used, as at Methye Portage. Sometimes railways or canals were built; when going downstream through rapids an experienced voyageur called the guide would inspect the rapids and choose between the heavy work of a portage and the life-threatening risk of running the rapids. If the second course were chosen, the boat would be controlled by the avant standing in front with a long paddle and the gouvernail standing in the back with a 2.7-metre steering paddle. The avant had a better view and was in charge but the gouvernail had more control over the boat; the other canoemen provided power under the instructions of the avant. Going upstream was more difficult, as there were many places where the current was too swift to paddle.
Where the river bottom was shallow and firm, voyageurs would stand in the canoe and push it upstream with 3-metre poles. If the shoreline was reasonably clear the canoe could be'tracked' or'lined', that is, the canoemen would pull the canoe on a rope while one man stayed on board to keep it away from the shore. In worse conditions, the'demi-chargé' technique was used. Half the cargo was unloaded, the canoe forced upstream and returned downstream to pick up the remaining half of the cargo. In still worse currents, the entire cargo was unloaded and carried overland while the canoe was forced upstream. In the worst case a full portage was necessary; the canoe was carried overland by two or four men The cargo was divided into standard 41-kilogram packs or pièces with each man responsible for about six. One portage or canoe pack would be carried by one on the back. To allow regular rests the voyageur would drop his pack at a pose about every 1 kilometre and go back for the next load; the time for a portage was estimated at one hour per half mile.
The Diolkos was a paved trackway in Ancient Greece which enabled boats to be moved overland across the Isthmus of Corinth between the Gulf of Corinth and the Saronic Gulf. It was constructed to transport high ranking Despots to conduct business in the justice system; the 6 km to 8.5 km long roadway was a rudimentary form of railway, operated from around 600 BC until the middle of the 1st century AD. The scale on which the Diolkos combined the two principles of the railway and the overland transport of ships was unique in antiquity. There is scant literary evidence for two more ship trackways referred to as diolkoi in antiquity, both located in Roman Egypt: The physician Oribasius records two passages from his 1st century AD colleague Xenocrates, in which the latter casually refers to a diolkos close to the harbor of Alexandria, which may have been located at the southern tip of the island of Pharos. Another diolkos is mentioned by Ptolemy in his book on geography as connecting a false mouth of a silted up Nile branch with the Mediterranean Sea.
The land link between Adige river and Garda lake in Northern Italy, hardly used by the smallest watercraft, was at least once used by the Venetian Republic for the transport of a military fleet in 1439. The land link is now somewhat harder because of the disappearance of Loppio lake. In the 8th, 9th and 10th centuries, Viking merchant-adventurers exploited a network of waterways in Eastern Europe, with portages connecting the four most important rivers of the region: Volga, Western Dvina and Don; the portages of what is now Russia were vital for the Varangian commerce with the Orient and Byzantium. At the most important portages there were trade outposts inhabited by a mixture of Norse merchants and native population; the Khazars built the fortress of Sarkel to guard a key portage between the Don. After Varangian and Khazar power in Eastern Europe waned, Slavic merchants continued to use the portages along the Volga trade route and the Dnieper trade route; the names of the towns Volokolamsk and Vyshny Volochek may be translated as "the portage on the Lama River" and "the little upper portage", res
A river mouth is the part of a river where the river debouches into another river, a lake, a reservoir, a sea, or an ocean. The water from a river can enter the receiving body in a variety of different ways; the motion of a river is influenced by the relative density of the river compared to the receiving water, the rotation of the earth, any ambient motion in the receiving water, such as tides or seiches. If the river water has a higher density than the surface of the receiving water, the river water will plunge below the surface; the river water will either form an underflow or an interflow within the lake. However, if the river water is lighter than the receiving water, as is the case when fresh river water flows into the sea, the river water will float along the surface of the receiving water as an overflow. Alongside these advective transports, inflowing water will diffuse. At the mouth of a river, the change in flow condition can cause the river to drop any sediment it is carrying; this sediment deposition can generate a variety of landforms, such as deltas, sand bars and tie channels.
Many places in the United Kingdom take their names from their positions at the mouths of rivers, such as Plymouth and Great Yarmouth. Confluence River delta Estuary Liman
The Laurentian Divide called the Northern Divide and locally the height of land, is a continental divide in central North America that separates the Hudson Bay watershed to the north from the Gulf of Mexico watershed to the south and the Great Lakes-St. Lawrence watershed to the southeast. Water north of the divide flows to Hudson Bay. From the divide's junction with the Continental Divide at Triple Divide Peak just south of the U. S. border in northwestern Montana, it runs north to just across the border east through southern Alberta to mid-Saskatchewan where it turns southeasterly reentering the U. S. at the northwestern corner of North Dakota. It continues on to the extreme northeast corner of South Dakota before crossing the middle of Minnesota's western border at the Traverse Gap; the divide runs north and east thru northern Minnesota lurching north thru Superior National Forest in the eastern tip into Ontario. There it passes over Lake Nipigon above the Great Lakes dipping to the 48th parallel before rising to cross the lower western border of Quebec just south of Lake Abitibi below James Bay.
It meanders northeasterly across Quebec to the lower southwestern boundary of Labrador. From there, it follows the boundary jaggedly north to Killiniq Island where it becomes the boundary between Nunavut and Labrador before reaching its terminus at Cape Chidley on the Labrador Sea; the divide hosts two triple divide points, one at its origin on Triple Divide Peak, in Glacier National Park, Montana where it intersects the Continental Divide considered the hydrological apex of North America. That peak divides the waters of the Columbia River watershed which flow to the Pacific Ocean from the waters of the Nelson River watershed which flow to Hudson Bay and the Mississippi River watershed which flows to the Gulf of Mexico; the other triple divide is at Hill of Three Waters near Hibbing, Minnesota where it intersects the St. Lawrence divide; this not a summit, but a highland plains where the watersheds of the Mississippi, Nelson and St. Lawrence River meet; the eastern portion of the divide marked the original northern boundary of both Ontario and Quebec provinces at the time of Confederation in 1867, although both have since expanded northward.
West of Lake Superior, the divide formed the northern boundary of the United States' Louisiana Purchase in 1803. Canadian shield or Laurentian Plateau Laurentia Grenville Orogeny Torngat Mountains of the Arctic Cordillera U. S. Geological Survey Geographic Names Information System: Laurentian Divide
An isthmus is a narrow piece of land connecting two larger areas across an expanse of water by which they are otherwise separated. A tombolo is an isthmus that consists of a spit or bar, a strait is the sea counterpart of an isthmus. Canals are built across isthmuses, where they may be a advantageous shortcut for marine transport. For example, the Panama Canal crosses the Isthmus of Panama, connecting the North Atlantic and Pacific Oceans. Another example is the Welland Canal in the Niagara Peninsula, it connects Lake Ontario to Lake Erie. The city of Auckland in the North Island of New Zealand is situated on an isthmus. Isthmus and land bridge are related terms with isthmus having a broader meaning. A land bridge is an isthmus connecting the Earth's major landmasses; the term land bridge is used in biogeology to describe land connections that used to exist between continents at various times and were important for migration of people, various species of animals and plants, e.g. Bering Land Bridge.
An isthmus is a land connection between two bigger landmasses, while a peninsula is rather a land protrusion, connected to a bigger landmass on one side only and surrounded by water on all other sides. Technically, an isthmus can have canals running from coast to coast, thus resemble two peninsulas. Major isthmuses include the Isthmus of Panama and the Isthmus of Tehuantepec in the Americas, the Isthmus of Kra in South-East Asia, the Isthmus of Suez between Africa and Asia, the Karelian Isthmus in Europe. Of historic importance was the Isthmus of Corinth in Greece. Land bridge List of isthmuses List of straits
Canada–United States border
The Canada–United States border known as the International Boundary, is the longest international border in the world between two countries. It is shared between Canada and the United States, the second- and fourth/third largest countries by area, respectively; the terrestrial boundary is 8,891 kilometres long, of which 2,475 kilometres is Canada's border with Alaska. Eight Canadian provinces and territories, thirteen U. S. states are located along the border. The Treaty of Paris of 1783 ended the American Revolutionary War between Great Britain and the United States. In the second article of the Treaty the parties agreed on all of the boundaries of the United States, including but not limited to the boundary with British North America to the north; the agreed boundary included the line from the northwest angle of Nova Scotia to the northwesternmost head of Connecticut River, proceeded down along the middle of the river to the 45th parallel of north latitude. That parallel had been established in the 1760s as the boundary between the provinces of Quebec and New York.
It was surveyed and marked by John Collins and Thomas Valentine from 1771 to 1773. The Saint Lawrence River and the Great Lakes became the boundary further west. Northwest of Lake Superior, the boundary followed rivers to the Lake of the Woods. From the Lake of the Woods, the boundary was agreed to go straight west until it met the Mississippi River. In fact that line never meets the river; the Jay Treaty of 1794 created the International Boundary Commission, charged with surveying and mapping the boundary. It provided for removal of British military and administration from Detroit and other frontier outposts on the U. S. side. It was superseded by the Treaty of Ghent concluding the War of 1812, which included pre-war boundaries; the Rush–Bagot Treaty of 1817 provided a plan for demilitarizing the two combatant sides in the War of 1812 and laid out preliminary principles for drawing a border between British North America and the United States. Westward expansion of both British North America and the United States saw the boundary extended west along the 49th parallel from the Northwest Angle at Lake of the Woods to the Rocky Mountains under the Treaty of 1818.
That treaty extinguished British claims south of that latitude to the Red River Valley, part of Rupert's Land. The treaty extinguished U. S. claims to land north of that line in the watershed of the Missouri River, part of the Louisiana Purchase. Along the 49th parallel, the border vista is theoretically straight but in practice follows the 19th-century surveyed border markers and varies by several hundred feet in spots. Disputes over the interpretation of the border treaties and mistakes in surveying required additional negotiations resulting in the Webster–Ashburton Treaty of 1842; the treaty resolved the dispute known as the Aroostook War over the boundary between Maine on the one hand, New Brunswick and the Province of Canada on the other. The treaty redefined the border between New Hampshire and New York on the one hand, the Province of Canada on the other, resolving the Indian Stream dispute and the Fort Blunder dilemma at the outlet to Lake Champlain; the part of the 45th parallel that separates Quebec from the U.
S. states of Vermont and New York had first been surveyed from 1771 to 1773 after it had been declared the boundary between New York and Quebec, it was surveyed again after the War of 1812. The U. S. federal government began to construct fortifications just south of the border at Rouses Point, New York, on Lake Champlain. After a significant portion of the construction was completed, measurements revealed that at that point, the actual 45th parallel was three-quarters of a mile south of the surveyed line; this created a dilemma for the United States, not resolved until a provision of the treaty left the border on the meandering line as surveyed. The border along the Boundary Waters in present-day Ontario and Minnesota between Lake Superior and the Northwest Angle was redefined. An 1844 boundary dispute during U. S. President James K. Polk's administration led to a call for the northern boundary of the U. S. west of the Rockies to be latitude 54° 40' north, but the United Kingdom wanted a border that followed the Columbia River to the Pacific Ocean.
The dispute was resolved in the Oregon Treaty of 1846, which established the 49th parallel as the boundary through the Rockies. The Northwest Boundary Survey laid out the land boundary, but the water boundary was not settled for some time. After the Pig War in 1859, arbitration in 1872 established the border between the Gulf Islands and the San Juan Islands; the International Boundary Survey, called the Northern Boundary Survey in the United States, began in 1872. Its mandate was to estab