The bald eagle is a bird of prey found in North America. A sea eagle, it forms a species pair with the white-tailed eagle, its range includes most of Canada and Alaska, all of the contiguous United States, northern Mexico. It is found near large bodies of open water with an abundant food supply and old-growth trees for nesting; the bald eagle is an opportunistic feeder which subsists on fish, which it swoops down and snatches from the water with its talons. It builds the largest nest of any North American bird and the largest tree nests recorded for any animal species, up to 4 m deep, 2.5 m wide, 1 metric ton in weight. Sexual maturity is attained at the age of four to five years. Bald eagles are not bald; the adult is brown with a white head and tail. The sexes are identical in plumage; the beak is hooked. The plumage of the immature is brown; the bald eagle is both the national bird and national animal of the United States of America. The bald eagle appears on its seal. In the late 20th century it was on the brink of extirpation in the contiguous United States.
Populations have since recovered and the species was removed from the U. S. government's list of endangered species on July 12, 1995 and transferred to the list of threatened species. It was removed from the List of Endangered and Threatened Wildlife in the Lower 48 States on June 28, 2007; the plumage of an adult bald eagle is evenly dark brown with a white tail. The tail is moderately long and wedge-shaped. Males and females are identical in plumage coloration, but sexual dimorphism is evident in the species, in that females are 25% larger than males; the beak and irises are bright yellow. The legs are feather-free, the toes are short and powerful with large talons; the developed talon of the hind toe is used to pierce the vital areas of prey while it is held immobile by the front toes. The beak is hooked, with a yellow cere; the adult bald eagle is unmistakable in its native range. The related African fish eagle has a brown body, white head and tail, but differs from the bald in having a white chest and black tip to the bill.
The plumage of the immature is a dark brown overlaid with messy white streaking until the fifth year, when it reaches sexual maturity. Immature bald eagles are distinguishable from the golden eagle, the only other large, non-vulturine raptorial bird in North America, in that the former has a larger, more protruding head with a larger beak, straighter edged wings which are held flat and with a stiffer wing beat and feathers which do not cover the legs; when seen well, the golden eagle is distinctive in plumage with a more solid warm brown color than an immature bald eagle, with a reddish-golden patch to its nape and a contrasting set of white squares on the wing. Another distinguishing feature of the immature bald eagle over the mature bird is its black, yellow-tipped beak; the bald eagle has sometimes been considered the largest true raptor in North America. The only larger species of raptor-like bird is the California condor, a New World vulture which today is not considered a taxonomic ally of true accipitrids.
However, the golden eagle, averaging 4.18 kg and 63 cm in wing chord length in its American race, is 455 g lighter in mean body mass and exceeds the bald eagle in mean wing chord length by around 3 cm. Additionally, the bald eagle's close cousins, the longer-winged but shorter-tailed white-tailed eagle and the overall larger Steller's sea eagle, may wander to coastal Alaska from Asia; the bald eagle has a body length of 70–102 cm. Typical wingspan is between 1.8 and 2.3 m and mass is between 3 and 6.3 kg. Females are about 25% larger than males, averaging as much as 5.6 kg, against the males' average weight of 4.1 kg. The size of the bird varies by location and corresponds with Bergmann's rule, since the species increases in size further away from the Equator and the tropics. For example, eagles from South Carolina average 3.27 kg in mass and 1.88 m in wingspan, smaller than their northern counterparts. One field guide in Florida listed small sizes for bald eagles there, at about 4.13 kg. Of intermediate size, 117 migrant bald eagles in Glacier National Park were found to average 4.22 kg but this was juvenile eagles, with 6 adults here averaging 4.3 kg.
Wintering eagles in Arizona were found to average 4.74 kg. The largest eagles are from Alaska, where large females may weigh more than 7 kg and span 2.44 m across the wings. A survey of adult weights in Alaska showed that females there weighed on average 5.35 kg and males weighed 4.23 kg against immatures which averaged 5.09 kg and 4.05 kg in the two sexes. An Alaskan adult female eagle, considered outsized we
North American beaver
The North American beaver is one of two extant beaver species. It is native to North America and introduced to Patagonia in South America and some European countries. In the United States and Canada, the species is referred to as "beaver", though this causes some confusion because another distantly related rodent, Aplodontia rufa, is called the "mountain beaver". Other vernacular names, including American beaver and Canadian beaver, distinguish this species from the other extant beaver species, Castor fiber, native to Eurasia; the North American beaver is an official animal symbol of Canada and is the official state mammal of Oregon. This beaver is the largest rodent in North America and competes with its Eurasian counterpart, the European beaver, for being the second-largest in the world, both following the South American capybara; the European species is larger on average but the American has a larger known maximum size. Adults weigh from 11 to 32 kg, with 20 kg being typical. In New York, the average weight of adult male beavers was 18.9 kg, while non-native females in Finland averaged 18.1 kg.
However, adults of both sexes averaged 16.8 kg in Ohio. The species seems to conform to Bergmann's rule. In the Northwest Territory, adults weighed a median of 20.5 kg. The American beaver is smaller in average body mass than the Eurasian species; the head-and-body length of adult North American beavers is 74–90 cm, with the tail adding a further 20–35 cm. Old individuals can exceptionally exceed normal sizes, weighing more than 40 kg or as much as 50 kg. Like the capybara, the beaver is semiaquatic; the beaver has many traits suited to this lifestyle. It has a large, paddle-shaped tail and large, webbed hind feet; the unwebbed front paws are smaller, with claws. The eyes are covered by a nictitating membrane; the nostrils and ears are sealed. A thick layer of fat under its skin insulates the beaver from its coldwater environment; the beaver's fur consists of short, fine inner hairs. The fur has a range of colors, but is dark brown. Scent glands near the genitals secrete an oily substance known as castoreum, which the beaver uses to waterproof its fur.
Before their near-extirpation by trapping in North America, beavers were ubiquitous and lived from the arctic tundra to the deserts of northern Mexico, from the Atlantic to the Pacific Oceans. Physician naturalist Edgar Alexander Mearns' 1907 report of beaver on the Sonora River may be the earliest report on the southernmost range of this North American aquatic mammal. However, beavers have been reported both and contemporaneously in Mexico on the Colorado River, Bavispe River, San Bernardino River in the states of Sonora and Chihuahua. Beavers are active at night, they are excellent may remain submerged up to 15 minutes. More vulnerable on land, they tend to remain in the water, they use their flat, scaly tail both to signal danger by slapping the surface of the water and as a location for fat storage. They construct their homes, or "lodges", out of sticks, twigs and mud in lakes and tidal river deltas; these lodges may be surrounded by water. Beavers are well known for building dams across streams and constructing their lodges in the artificial ponds which form.
When building in a pond, the beavers first make a pile of sticks and eat out one or more underwater entrances and two platforms above the water surface inside the pile. The first is used for drying off. Towards winter, the lodge is plastered with mud which, when it freezes, has the consistency of concrete. A small air hole is left in the top of the lodge; the purpose of the dam is to create deepwater refugia enabling the beaver to escape from predators. When deep water is present in lakes, rivers, or larger streams, the beaver may dwell in a bank burrow and bank lodge with an underwater entrance; the beaver dam is constructed using branches from trees the beavers cut down, as well as rocks and mud. The inner bark, twigs and leaves of such trees are an important part of the beaver's diet; the trees are cut down using their strong incisor teeth. Their front paws are used for digging and carrying and placing materials; the sound of running water dictates where a beaver builds its dam. Besides providing a safe home for the beaver, beaver ponds provide habitat for waterfowl and other aquatic animals.
Their dams can help reduce flooding. However, beaver dams are not permanent and depend on the beavers' continued presence for their maintenance. Beavers concentrate on building and repairing dams in the fall in preparation for the coming winter. In northern areas, they do not repair breaches in the dam made by otters, sometimes breach the dam themselves and lower the water level in the pond to create more breathing space under the ice or get easier access to trees below the dam. In a 1988 study in Alberta, Canada, no beavers repaired "sites of water loss" during the winter. Of 178 sites of water loss, beavers repaired 78 when water was opened, did not repair 68; the rest were repaired. Beavers are best known for their dam-building, they maintain their pond-habitat by reacting to the sound of running water, damming it up with tree branches and mud. Early ecologists believed that this dam-building was an amazi
The American mink is a semiaquatic species of mustelid native to North America, though human intervention has expanded its range to many parts of Europe and South America. Because of range expansion, the American mink is classed as a least-concern species by the IUCN. Since the extinction of the sea mink, the American mink is the only extant member of the genus Neovison; the American mink is a carnivore that feeds on rodents, crustaceans and birds. In its introduced range in Europe it has been classified as an invasive species linked to declines in European mink, Pyrenean desman, water vole populations, it is the animal most farmed for its fur, exceeding the silver fox, sable and skunk in economic importance. Aleut: ilgitux̂ Blackfoot: aapssiiyai'kayi or soyii'kayi Chickasaw: okfincha Chipewyan: tthełjus Cree: sâkwes Lakhota: ikhúsą Lushootseed: c̓əbál̓qid or bə́ščəb Salish: c̓xlicn̓ Ojibwe: zhaanggweshi Tuscarora: θenę́·ku·t As a species, the American mink represents a more specialized form than the European mink in the direction of carnivory, as indicated by the more developed structure of the skull.
Fossil records of the American mink go back as far as the Irvingtonian, though the species is uncommon among Pleistocene animals. Its fossil range corresponds with the species' current natural range; the American minks of the Pleistocene did not differ much in size or morphology from modern populations, though a slight trend toward increased size is apparent from the Irvingtonian through to the Illinoian and Wisconsinan periods. Although superficially similar to the European mink, studies indicate the American mink's closest relative is the Siberian weasel of Asia; the American mink has been recorded to hybridize with European minks and polecats in captivity, though the hybrid embryos of the American and European minks are reabsorbed. As of 2005, 15 subspecies are recognised; the American mink differs from members of the genus Mustela by its larger size and stouter form, which approach those of martens. It shares with martens a uniformly enlarged and somewhat tapering tail, rather than a slenderly terete tail with an enlarged bushy tip, as is the case in stoats.
The American mink is similar in build to the European mink. The American mink has a long body, its streamlined shape helps it to reduce water resistance whilst swimming. The skull is similar to that of the European mink, but is more massive and less elongated, with more developed projections and a wider, shorter cranium; the upper molars are more massive than those of the European mink. The dental formula is 188.8.131.52.1.3.2. Domestic mink, which are bred in fur farms and are substandard genetically, have 19.6% smaller brains, 8.1% smaller hearts, 28.2% smaller spleens than wild mink. The feet are broad, with webbed digits, it has eight nipples, with one pair of inguinal teats and three pairs of abdominal teats. The adult male's penis is 2.2 in long, is covered by a sheath. The baculum curved at the tip. Males measure 13 -- 18 in in body length -- 15 in; the tail measures 6–10 inches in males and 6–8 in in females. Weights vary with males being heavier than females. In winter, males weigh 1 -- females 1 -- 2 lb.
Maximum heaviness occurs in autumn. The American mink's winter fur is denser, longer and more close-fitting than that of the European mink; the winter fur's tone is very dark blackish-tawny to light-tawny. Colour is evenly distributed over all the body, with the lower side being only lighter than the upper body; the guard hairs are bright and dark-tawny approaching black on the spine. The underfur on the back is wavy and greyish-tawny with a bluish tint; the tail sometimes becomes pure black on the tip. The chin and lower lip are white. Captive individuals tend to develop irregular white patches on the lower surface of their bodies, though escaped individuals from Tartaria lost these patches; the summer fur is shorter and duller than the winter fur. The thick underfur and oily guard hairs render the pelage water-resistant, with the length of the guard hairs being intermediate between those of otters and polecats, thus indicating the American mink is incompletely adapted to an aquatic life, it moults twice a year, during autumn.
It does not turn white in winter. A variety of different colour mutations have arisen from experimental breeding on fur farms. On land, the American mink moves with speeds of up to 6.5 km/h. It climbs trees and swims well. During swimming, the mink propels itself through undulating movements of the trunk; when diving, it undergoes a state of rapid bradycardia, an adaptation to conserve oxygen. In warm water, the American mink can swim for three hours without stopping, but in cold water it can die within 27 minutes, it dives to depths of 12 in for 10 seconds, though depths of 3 m lasting 60 seconds have been recorded. It catches fish after five- to 20-second chases; the American mink relies on sight when foraging. Its eyesight is clearer on land than underwater, its auditory perception is high enough to detect the ultrasonic vocalisations of rodent prey. Its sense of smell is comparatively weak, its two anal glands are used for scent marking, either through defecation or by rubbing the anal region on the ground.
Lewis and Clark Expedition
The Lewis and Clark Expedition from May 1804 to September 1806 known as the Corps of Discovery Expedition, was the first American expedition to cross the western portion of the United States. It began in Pittsburgh, Pa, made its way westward, passed through the Continental Divide of the Americas to reach the Pacific coast; the Corps of Discovery was a selected group of US Army volunteers under the command of Captain Meriwether Lewis and his close friend Second Lieutenant William Clark. President Thomas Jefferson commissioned the expedition shortly after the Louisiana Purchase in 1803 to explore and to map the newly acquired territory, to find a practical route across the western half of the continent, to establish an American presence in this territory before Britain and other European powers tried to claim it; the campaign's secondary objectives were scientific and economic: to study the area's plants, animal life, geography, to establish trade with local American Indian tribes. The expedition returned to St. Louis to report its findings to Jefferson, with maps and journals in hand.
One of Thomas Jefferson's goals was to find "the most direct and practicable water communication across this continent, for the purposes of commerce." He placed special importance on declaring US sovereignty over the land occupied by the many different Indian tribes along the Missouri River, getting an accurate sense of the resources in the completed Louisiana Purchase. The expedition made notable contributions to science, but scientific research was not the main goal of the mission. During the 19th century, references to Lewis and Clark "scarcely appeared" in history books during the United States Centennial in 1876, the expedition was forgotten. Lewis and Clark began to gain attention around the start of the 20th century. Both the 1904 Louisiana Purchase Exposition in St. Louis and the 1905 Lewis and Clark Centennial Exposition in Portland, Oregon showcased them as American pioneers. However, the story remained shallow until mid-century as a celebration of US conquest and personal adventures, but more the expedition has been more researched.
In 2004, a complete and reliable set of the expedition's journals was compiled by Gary E. Moulton. In the 2000s, the bicentennial of the expedition further elevated popular interest in Lewis and Clark; as of 1984, no US exploration party was more famous, no American expedition leaders are more recognizable by name. Jefferson met John Ledyard in Paris in the 1780s, they discussed a possible trip to the Pacific Northwest. Jefferson had read Captain James Cook's A Voyage to the Pacific Ocean, an account of Cook's third voyage, Le Page du Pratz's The History of Louisiana, all of which influenced his decision to send an expedition. Like Captain Cook, he wished to discover a practical route through the Northwest to the Pacific coast. Alexander Mackenzie had charted a route in his quest for the Pacific, following the Mackenzie River to the Arctic Ocean in 1789. Mackenzie and his party were the first to cross America north of Mexico to the Pacific when he arrived near Bella Coola, British Columbia in 1793—a dozen years before Lewis and Clark.
Mackenzie's accounts in Voyages from Montreal informed Jefferson of Britain's intent to control the lucrative fur trade of the Columbia River and convinced him of the importance of securing the territory as soon as possible. Two years into his presidency, Jefferson asked Congress to fund an expedition through the Louisiana territory to the Pacific Ocean, he did not attempt to make a secret of the Lewis and Clark expedition from Spanish and British officials, but rather claimed different reasons for the venture. He used a secret message to ask for funding due to poor relations with the opposition Federalist Party in Congress. In 1803, Jefferson commissioned the Corps of Discovery and named Army Captain Meriwether Lewis its leader, who selected William Clark as second in command. Lewis demonstrated remarkable skills and potential as a frontiersman, Jefferson made efforts to prepare him for the long journey ahead as the expedition was gaining approval and funding. Jefferson explained his choice of Lewis: It was impossible to find a character who to a complete science in botany, natural history, mineralogy & astronomy, joined the firmness of constitution & character, habits adapted to the woods & a familiarity with the Indian manners and character, requisite for this undertaking.
All the latter qualifications Capt. Lewis has. In 1803, Jefferson sent Lewis to Philadelphia to study medicinal cures under Benjamin Rush, a physician and humanitarian, he arranged for Lewis to be further educated by Andrew Ellicott, an astronomer who instructed him in the use of the sextant and other navigational instruments. Lewis, was not ignorant of science and had demonstrated a marked capacity to learn with Jefferson as his teacher. At Monticello, Jefferson possessed the largest library in the world on the subject of the geography of the North American continent, Lewis had full access to it, he spent time conferring with Jefferson. Lewis and Clark met near Louisville, Kentucky in October 1803 at the Falls of the Ohio and the core "Nine Young Men" were enlisted into the Corps of Discovery, their goals were to explore the vast territory acquired by the Louisiana Purchase and to establish trade and US sovereignty over the Indians along the Missouri River. Jefferson wanted to establish a US claim of "discovery" to the Pacific Northwest and Oregon territory by documenting an American presence there before European nations could claim the land.
According to some historians, Jefferson understood that he would have
The fisher is a small, carnivorous mammal native to North America. It is a member of the mustelid family, is in the monospecific genus Pekania; the fisher is related to, but larger than the American marten. The fisher is a forest-dwelling creature whose range covers much of the boreal forest in Canada to the northern United States. Names derived from aboriginal languages include pekan, pequam and woolang, it is sometimes misleadingly referred to as a fisher cat. Males and females look similar. Adult males weigh 3.5 to 6.0 kilograms. Adult females weigh 2.0 to 2.5 kg. The fur of the fisher varies seasonally, being glossier in the winter. During the summer, the color becomes more mottled; the fisher prefers to hunt in full forest. Although an agile climber, it spends most of its time on the forest floor, where it prefers to forage around fallen trees. An omnivore, the fisher feeds on a wide variety of small animals and on fruits and mushrooms, it prefers the snowshoe hare and is one of the few animals able to prey on porcupines.
Despite its common name, it eats fish. The reproductive cycle of the fisher lasts a year. Female fishers give birth to four kits in the spring, they nurse and care for their kits until late summer, when they are old enough to set out on their own. Females enter estrus shortly after giving leave the den to find a mate. Implantation of the blastocyst is delayed until the following spring, when they give birth and the cycle is renewed. Fishers have few predators besides humans, they have been trapped since the 18th century for their fur. Their pelts were in such demand that they were extirpated from several parts of the United States in the early part of the 20th century. Conservation and protection measures have allowed the species to rebound, but their current range is still reduced from its historic limits. In the 1920s, when pelt prices were high, some fur farmers attempted to raise fishers. However, their unusual delayed reproduction made breeding difficult; when pelt prices fell in the late 1940s, most fisher farming ended.
While fishers avoid human contact, encroachments into forest habitats have resulted in some conflicts. Despite the name "fisher", the animal is not known to eat fish; the name is instead related to the word "fitch", meaning a European polecat or pelt thereof, due to the resemblance to that animal. The name comes from colonial Dutch equivalent visse. In the French language, the pelt of a polecat is called fiche or fichet. In some regions, the fisher is known as a pekan, derived from its name in the Abenaki language. Wejack is an Algonquian word borrowed by fur traders. Other American Indian names for the fisher are Chipewyan thacho and Carrier chunihcho, both meaning "big marten", Wabanaki uskool; the Latin specific name pennanti honors Thomas Pennant, who described the fisher in 1771. Buffon had first described the creature in 1765. Pennant called it a fisher, unaware of Buffon's earlier description. Other 18th-century scientists gave it similar names, such as Schreber, who named it Mustela canadensis, Boddaert, who named it Mustela melanorhyncha.
The fisher was placed in the genus Martes by Smith in 1843. In 2008, advances in DNA analysis allowed a more detailed study of the fisher's evolutionary history; the fisher and the Martes genera were determined to have descended from a common ancestor, but the fisher was distinct enough to put it in its own genus. It was decided to reclassify the fisher as Pekania pennanti. Members of the genus Pekania are distinguished by their four premolar teeth on the upper and lower jaws, its close relative Mustela has just three. The fisher has 38 teeth; the dentition formula is: 184.108.40.206.1.4.2 Some evidence shows that ancestors of the fisher migrated to North America during the Pliocene era between 2.5 and 5.0 million years ago. Two extinct mustelids, M. palaeosinensis and M. anderssoni, have been found in eastern Asia. The first true fisher, M. divuliana, has only been found in North America. M. divuliana is indicated to be related to the Asian finds, which suggests a migration. M. pennanti has been found as early as the Late Pleistocene era, about 125,000 years ago.
No major differences are seen between the modern fisher. Fossil evidence indicates. Three subspecies were identified by Goldman in 1935, M. p. columbiana, M. p. pacifica, M. p. pennanti. Research has debated whether these subspecies could be positively identified. In 1959, E. M. Hagmeier concluded that the subspecies are not separable based on either fur or skull characteristics. Although some debate still exists, in general, the fisher is recognized to be a monotypic species with no extant subspecies. Fishers are a medium-sized mammal, comparable in size to the domestic cat, their bodies are long and low to the ground. The sexes have similar physical features, but they are sexually dimorphic in size, with the male being much larger than the female. Males weigh 3.5 to 6.0 kg. Females weigh 2.0 to 2.5 kg. The largest male fisher recorded weighed 9 kg; the fisher's fur changes with the season and differs between sexes. Males have coarser coats than females. In the early winter, the coats are dense and gl
William Clark was an American explorer, Indian agent, territorial governor. A native of Virginia, he grew up in prestatehood Kentucky before settling in what became the state of Missouri. Clark was a slaveholder. Along with Meriwether Lewis, Clark helped lead the Lewis and Clark Expedition of 1804 to 1806 across the Louisiana Purchase to the Pacific Ocean, claimed the Pacific Northwest for the United States. Before the expedition, he served in the United States Army. Afterward, he served as governor of the Missouri Territory. From 1822 until his death in 1838, he served as Superintendent of Indian Affairs. William Clark was born in Caroline County, Virginia, on August 1, 1770, the ninth of ten children of John and Ann Rogers Clark, his parents were natives of King and Queen County, were of English and Scots ancestry. The Clarks owned several modest estates and a few slaves, they were members of the Anglican Church. Clark did not have any formal education. In years, he was self-conscious about his convoluted grammar and inconsistent spelling—he spelled "Sioux" 27 different ways in his journals of the Lewis and Clark Expedition—and sought to have his journals corrected before publication.
The spelling of American English was not standardized in Clark's youth, but his vocabulary suggests he was well read. Clark's five older brothers fought in Virginia units during the American Revolutionary War, but William was too young, his oldest brother, Jonathan Clark, served as a colonel during the war, rising to the rank of brigadier general in the Virginia militia years afterward. His second-oldest brother, George Rogers Clark, rose to the rank of general, spending most of the war in Kentucky fighting against British-allied American Indians. After the war, the two oldest Clark brothers made arrangements for their parents and family to relocate to Kentucky. William, his parents, his three sisters, the Clark family's slaves arrived in Kentucky in March 1785, having first traveled overland to Redstone Landing in present-day Brownsville, Pennsylvania, they completed the journey down the Ohio River by flatboat. The Clark family settled at "Mulberry Hill", a plantation along Beargrass Creek near Louisville.
This was William Clark's primary home until 1803. In Kentucky, his older brother George Rogers Clark taught William wilderness survival skills. Kentuckians fought the Northwest Indian War against American Indians, who were trying to preserve their territory north of the Ohio River. In 1789, 19-year-old William Clark joined a volunteer militia force under Major John Hardin. Clark kept a detailed journal of the expedition. Hardin was advancing against the Wea Indians, raiding settlements in Kentucky, on the Wabash River. In error, the undisciplined Kentucky militia attacked a peaceful Shawnee hunting camp, where they killed a total of eight men and children. In 1790, Clark was commissioned by General Arthur St. Clair, governor of the Northwest Territory, as a captain in the Clarksville, Indiana militia. One older source says he was sent on a mission to the Creek and Cherokee, whom the US hoped to keep out of the war, in the Southeast, his responsibilities are unclear. He may have visited New Orleans at that time.
His travels prevented him from participating in General Josiah Harmar's disastrous campaign into the Northwest Territory that year. In 1791, Clark served as an ensign and acting lieutenant with expeditions under generals Charles Scott and James Wilkinson, he enlisted in the Legion of the United States and was commissioned as a lieutenant on March 6, 1792 under Anthony Wayne. On September 4, 1792 he was assigned to the 4th Sub-Legion, he was involved in several skirmishes with Indians during the continuing Northwest Indian War. At the Battle of Fallen Timbers in 1794, Clark commanded a company of riflemen who drove back the enemy on the left flank, killing a number of Native Americans and Canadians; this decisive US victory brought the Northwest Indian War to an end. In 1795, Clark was dispatched on a mission to Missouri. Clark served as an adjutant and quartermaster while in the militia. William Clark resigned his commission on July 4, 1796 and retired due to poor health, although he was only 26 years old.
He returned to his family's plantation near Louisville. In 1803, Meriwether Lewis recruited Clark age 33, to share command of the newly formed Corps of Discovery, whose mission was to explore the territory of the Louisiana Purchase, establish trade with Native Americans and the sovereignty of the US, they were to find a waterway from the US to the Pacific Ocean and claim the Oregon territory for the United States before European nations did. Clark spent three years on the expedition to the Pacific Coast. A slave owner known to deal harshly with his slaves, he brought one of his slaves, with him; the indigenous nations treated York with respect, many of the Native Americans were interested in his appearance, which "played a key role in diplomatic relations". Although Clark was refused a promotion to the rank of captain when Jefferson asked the Senate to appoint him, at Lewis' insistence, he exercised equal authority, continued the mission. Clark concentrated chiefly on the drawing of maps, the management of the expedition's supplies, leading hunting expeditions for game.
In 1807, President Jefferson appointed Clark as the brigadier general of the militia in the Louisiana Territory, the US agent for Indian affairs. At the time, trade was a major goal and the US established the factory system; the government and its appointees licensed traders to set up trading posts in N
The muskrat, the only species in genus Ondatra and tribe Ondatrini, is a medium-sized semiaquatic rodent native to North America and is an introduced species in parts of Europe and South America. The muskrat is found in wetlands over a wide range of habitats, it has important effects on the ecology of wetlands, is a resource of food and fur for humans. The muskrat is the largest species in the subfamily Arvicolinae, which includes 142 other species of rodents voles and lemmings. Muskrats are referred to as "rats" in a general sense because they are medium-sized rodents with an adaptable lifestyle and an omnivorous diet, they are not, members of the genus Rattus. The muskrat's name comes from a word of Algonquian origin, muscascus, or from the Abenaki native word mòskwas, as seen in the archaic English name for the animal, musquash; because of the association with the "musky" odor, which the muskrat uses to mark its territory, its flattened tail, the name became altered to musk-beaver. Its specific name zibethicus means "musky", being the adjective of zibethus "civet musk.
The genus name comes from the Huron word for the animal and entered New Latin as Ondatra via French. An adult muskrat is about 40–70 cm long, half of, the tail, weighs from 0.6–2 kg. That is about four times the weight of the brown rat, though an adult muskrat is only longer, are certainly the largest and heaviest members of the diverse family Cricetidae, which includes all voles and most mice native to the Americas. Muskrats are much smaller than beavers, with which they share their habitat. Muskrats are covered with short, thick fur, medium to dark brown or black in color, with the belly a bit lighter; the fur has two layers. They have long tails covered with scales rather than hair, to aid them in swimming, are flattened vertically, a shape, unique to them; when they walk on land, their tails drag on the ground. Muskrats are well suited for their semiaquatic life, they can swim under water for 12 to 17 minutes. Their bodies, like those of seals and whales, are less sensitive to the buildup of carbon dioxide than those of most other mammals.
They can close off their ears to keep the water out. Their hind feet are semiwebbed, although in swimming, their tails are their main means of propulsion. Muskrats are found over the United States and a small part of northern Mexico, they were introduced to Europe in the beginning of the 20th century and have become an invasive species in northwestern Europe. They inhabit wetlands, areas in or near saline and freshwater wetlands, lakes, or ponds, they are not found in Florida, where the round-tailed muskrat, or Florida water rat, fills their ecological niche. Their populations cycle, they are thought to play a major role in determining the vegetation of prairie wetlands in particular. They selectively remove preferred plant species, thereby changing the abundance of plant species in many kinds of wetlands. Species eaten include cattail and yellow water lily. Alligators are thought to be an important natural predator, the absence of muskrats from Florida may in part be the result of alligator predation.
While much wetland habitat has been eliminated due to human activity, new muskrat habitat has been created by the construction of canals or irrigation channels, the muskrat remains common and widespread. They are able to live alongside streams which contain the sulfurous water that drains away from coal mines. Fish and frogs perish in such streams, yet muskrats may occupy the wetlands. Muskrats benefit from human persecution of some of their predators; the muskrat is classed as a "prohibited new organism" under New Zealand's Hazardous Substances and New Organisms Act 1996, preventing it from being imported into the country. Trematode Metorchis conjunctus can infect muskrats. Muskrats live in groups consisting of a male and female pair and their young. During the spring, they fight with other muskrats over territory and potential mates. Many are killed in these fights. Muskrat families build nests to their young from cold and predators. In streams, ponds, or lakes, muskrats burrow into the bank with an underwater entrance.
These entrances are 6–8 in wide. In marshes, push-ups are constructed from mud; these push-ups are up to 3 ft in height. In snowy areas, they keep the openings to their push-ups closed by plugging them with vegetation, which they replace every day; some muskrat push-ups have to be replaced each year. Muskrats build feeding platforms in wetlands, they help maintain open areas in marshes. Muskrats are most active near dawn and dusk, they feed on cattail and other aquatic vegetation. They do not store food for the winter, but sometimes eat the insides of their push-ups. While they may appear to steal food beavers have stored, more cooperative partnerships with beavers exist, as featured in the BBC David Attenborough wildlife documentary The Life of Mammals. Plant materials compose about 95% of their