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84-493: Not to be confused with Beaver . Beever is a surname and may refer to: Alex Beever (born 1973), British rower Julian Beever (born c. 1959), British chalk artist Mary Beever (1802–1883), British artist and botanist Ross Beever (1946–2010), New Zealand geneticist and mycologist See also [ edit ] Beevers - English surname Beaver - an animal [REDACTED] Surname list This page lists people with

168-418: A freeboard above the water level. When heavy rains occur, the river or lake fills up. Afterward the dam gradually releases the extra stored water, thus somewhat reducing the height of the flood wave moving down the river. The surface of any stream intersects the surrounding water table. By raising the stream level, the gradient of the surface of the water table above the beaver dam is reduced, and water near

252-399: A generalist diet. During the spring and summer, they mainly feed on herbaceous plant material such as leaves, roots, herbs, ferns, grasses, sedges , water lilies , water shields , rushes , and cattails . During the fall and winter, they eat more bark and cambium of woody plants; tree and shrub species consumed include aspen , birch , oak , dogwood , willow and alder . There

336-471: A gradient (steepness) of one percent, though they have been recorded using streams with gradients as high as 15 percent. Beavers are found in wider streams more often than in narrower ones. They also prefer areas with no regular flooding and may abandon a location for years after a significant flood. Beavers typically select flat landscapes with diverse vegetation close to the water. North American beavers prefer trees being 60 m (200 ft) or less from

420-415: A hypothalamus that is much smaller than the cerebrum ; this indicates a relatively advanced brain with higher intelligence. The cerebellum is large, allowing the animal to move within a three-dimensional space (such as underwater) similar to tree-climbing squirrels. The neocortex is devoted mainly to touch and hearing. Touch is more advanced in the lips and hands than the whiskers and tail. Vision in

504-520: A polymer of β-glucose monomers . (This creates a more crystalline structure than is found in starch , which is composed of α-glucose monomers. Cellulose is a type of polysaccharide .) Many bacteria produce cellulase which can split off the glucose and use it for energy. Just as algae receive energy from sunlight, these bacteria derive energy from cellulose, and form the base of a very similar food chain. Additionally, bacterial populations absorb nitrogen and phosphorus compounds as they pass by in

588-655: A semiaquatic lifestyle. Members of the subfamily Castoroidinae are considered to be a sister group to modern beavers, and included giants like Castoroides of North America and Trogontherium of Eurasia. Castoroides is estimated to have had a length of 1.9–2.2 m (6.2–7.2 ft) and a weight of 90–125 kg (198–276 lb). Fossils of one genus in Castoroidinae, Dipoides , have been found near piles of chewed wood, though Dipoides appears to have been an inferior woodcutter compared to Castor . Researchers suggest that modern beavers and Castoroidinae shared

672-447: A "prohibited new organism" preventing them from being introduced into the country. Beavers live in freshwater ecosystems such as rivers, streams, lakes and ponds. Water is the most important component of beaver habitat; they swim and dive in it, and it provides them refuge from land predators. It also restricts access to their homes and allows them to move building objects more easily. Beavers prefer slower moving streams, typically with

756-400: A "raft"; when the top becomes frozen, it creates a "cap". The beaver accesses the raft by swimming under the ice. Many populations of Eurasian beaver do not make rafts, but forage on land during winter. Beavers usually live up to 10 years. Felids , canids , and bears may prey upon them. Beavers are protected from predators when in their lodges, and prefer to stay near water. Parasites of

840-531: A bark-eating common ancestor . Dam and lodge-building likely developed from bark-eating, and allowed beavers to survive in the harsh winters of the subarctic . There is no conclusive evidence for this behavior occurring in non- Castor species. The genus Castor likely originated in Eurasia . The earliest fossil remains appear to be C. neglectus , found in Germany and dated 12–10 mya. Mitochondrial DNA studies place

924-437: A beaver about 20 minutes to cut down a 15-centimetre (5.9 in) wide aspen, by gnawing a groove around the trunk in an hourglass shape. A beaver's jaws are powerful enough to cut a 1.5-centimetre (0.59 in) sapling in one bite. Maintenance work on the dam and lodges is often done in autumn. If beavers are considered central place foragers , their canals may be considered an extension of their "central place" far beyond

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1008-466: A conical, muscular, hairy base; the remaining two-thirds of the appendage is flat and scaly. The tail has multiple functions: it provides support for the animal when it is upright (such as when chewing down a tree), acts as a rudder when it is swimming, and stores fat for winter. It also has a countercurrent blood vessel system which allows the animal to lose heat in warm temperatures and retain heat in cold temperatures. The beaver's sex organs are inside

1092-441: A dam, although the average is 10 to 30 centimetres (3.9 to 11.8 in). Log length depends on the diameter of the tree and the size of the beaver. There are recorded cases of beavers felling trees of 45 metres (148 ft) tall and 115 centimetres (45 in) in diameter. Logs of this size are not intended to be used as structural members of the dam; rather, the bark is used for food, and sometimes to get to upper branches. It takes

1176-674: A dam, beavers stack up relatively long and thick logs between banks and in opposite directions. Heavy rocks keep them stable, and grass is packed between them. Beavers continue to pile on more material until the dam slopes in a direction facing upstream. Dams can range in height from 20 cm (7.9 in) to 3 m (9.8 ft) and can stretch from 0.3 m (1 ft 0 in) to several hundred meters long. Beaver dams are more effective in trapping and slowly leaking water than man-made concrete dams. Lake-dwelling beavers do not need to build dams. Beavers make two types of lodges: bank lodges and open-water lodges. Bank lodges are burrows dug along

1260-1010: A height of 2 m (6 ft 7 in) and an above-water diameter of 6 m (20 ft). A lodge sturdy enough to withstand the coming winter can be finished in just two nights. Both lodge types can be present at a beaver site. During the summer, beavers tend to use bank lodges to keep cool. They use open-water lodges during the winter. The air vent provides ventilation, and newly added carbon dioxide can be cleared in an hour. The lodge remains consistent in oxygen and carbon dioxide levels from season to season. Beavers in some areas will dig canals connected to their ponds. The canals fill with groundwater and give beavers access and easier transport of resources, as well as allow them to escape predators. These canals can stretch up to 1 m (3 ft 3 in) wide, 0.5 m (1 ft 8 in) deep, and over 0.5 km (0.31 mi) long. It has been hypothesized that beavers' canals are not only transportation routes but an extension of their " central place " around

1344-461: A liquid substance used mainly for marking territory. Anal glands produce an oily substance which the beaver uses as a waterproof ointment for its coat. The substance plays a role in individual and family recognition. Anal secretions are darker in females than males among Eurasian beavers, while the reverse is true for the North American species. Compared to many other rodents, a beaver's brain has

1428-423: A more grooved palatine (with the opening shifted towards the front), and reduced incisive foramen . Members of the subfamily Palaeocastorinae appeared in late-Oligocene North America. This group consisted primarily of smaller animals with relatively large front legs, a flattened skull, and a reduced tail—all features of a fossorial (burrowing) lifestyle. In the early Miocene (about 24 mya), castorids evolved

1512-463: A number of freshwater habitats , such as rivers, streams, lakes and ponds. They are herbivorous , consuming tree bark , aquatic plants , grasses and sedges . Beavers build dams and lodges using tree branches, vegetation, rocks and mud; they chew down trees for building material. Dams restrict water flow, and lodges serve as shelters. Their infrastructure creates wetlands used by many other species, and because of their effect on other organisms in

1596-460: A pond for them to live in, and for lodges, which act as shelters and refuges from predators and the elements. Without such material, beavers dig burrows into a bank to live. Dam construction begins in late summer or early fall, and they repair them whenever needed. Beavers can cut down trees up to 15 cm (5.9 in) wide in less than 50 minutes. Thicker trees, at 25 cm (9.8 in) wide or more, may not fall for hours. When chewing down

1680-496: A problem to Earth's ecology as carbon dioxide production. Studies have shown that beaver dams along a stream contribute to denitrification (the conversion of nitrogen compounds back into nitrogen). Bacteria in the dirt and the plant debris, which collects at the dams, turns nitrates into nitrogen gas. The gas bubbles to the surface and mixes with the atmosphere once more. Beaver dams and the associated ponds can provide nurseries for salmon and trout . An early indication of this

1764-621: A remarkable comeback in the United States (after near extirpation in the nineteenth century) and are likely to continually recolonize suitable habitat. Modern solutions include relatively cost-effective and low maintenance flow devices . Introduced to an area without its natural predators, as in Tierra del Fuego , beavers have flooded thousands of acres of land and are considered a plague. One notable difference in Tierra del Fuego from most of North America

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1848-758: A role. After they are born, the kits spend their first one to two months in the lodge. Kits suckle for as long as three months, but can eat solid food within their second week and rely on their parents and older siblings to bring it to them. Eventually, beaver kits explore outside the lodge and forage on their own, but may follow an older relative and hold onto their backs. After their first year, young beavers help their families with construction. Beavers sexually mature around 1.5–3 years. They become independent at two years old, but remain with their parents for an extra year or more during times of food shortage, high population density, or drought. Beaver dam A minimum water level of 0.6 to 0.9 metres (2.0 to 3.0 ft)

1932-400: A thick enamel that is colored orange or reddish-brown by iron compounds. The lower incisors have roots that are almost as long as the entire lower jaw. Beavers have one premolar and three molars on all four sides of the jaws, adding up to 20 teeth. The molars have meandering ridges for grinding woody material. The eyes, ears and nostrils are arranged so that they can remain above water while

2016-423: A tree, beavers switch between biting with the left and right side of the mouth. Tree branches are then cut and carried to their destination with the powerful jaw and neck muscles. Other building materials, like mud and rocks, are held by the forelimbs and tucked between the chin and chest. Beavers start building dams when they hear running water, and the sound of a leak in a dam triggers them to repair it. To build

2100-400: Is 775 metres (2,543 ft) long. Satellite photos provided by NASA WorldWind show the dam did not exist in 1975, but it appeared in subsequent images. It has two or more lodges and is a combination of two original dams. Google Earth images show new dams being built which could ultimately join the main dam and increase the overall length by another 50 to 100 metres (160 to 330 ft) during

2184-823: Is different from Wikidata All set index articles Beaver Beavers (genus Castor ) are large, semiaquatic rodents of the Northern Hemisphere . There are two existing species : the North American beaver ( Castor canadensis ) and the Eurasian beaver ( C. fiber ). Beavers are the second-largest living rodents, after capybaras , weighing up to 50 kg (110 lb). They have stout bodies with large heads, long chisel-like incisors , brown or gray fur , hand-like front feet, webbed back feet, and tails that are flat and scaly. The two species differ in skull and tail shape and fur color. Beavers can be found in

2268-442: Is directed more towards the brain. A beaver's body also has a high tolerance for carbon dioxide. When surfacing, the animal can replace 75 percent of the air in its lungs in one breath, compared to 15 percent for a human. The IUCN Red List of mammals lists both beaver species as least concern . The North American beaver is widespread throughout most of the United States and Canada and can be found in northern Mexico. The species

2352-540: Is required to keep the underwater entrance to beaver lodges from being blocked by ice during the winter. In lakes, rivers and large streams with deep enough water, beavers may not build dams, and live in bank burrows and lodges. Beavers start construction by diverting the stream to lessen the water's flow pressure. Branches and logs are then driven into the mud of the stream bed to form a base. Then sticks, bark (from deciduous trees), rocks, mud, grass, leaves, masses of plants, and anything else available are used to build

2436-402: Is some disagreement about why beavers select specific woody plants; some research has shown that beavers more frequently select species which are more easily digested, while others suggest beavers principally forage based on stem size. Beavers may cache their food for the winter, piling wood in the deepest part of their pond where it cannot be reached by other browsers . This cache is known as

2520-577: Is that the trees in Tierra del Fuego cannot be coppiced as can willows, poplars, aspens, and other North American trees. Thus the damage by the beavers seems more severe. The beaver's disruption is not limited to human geography; beavers can destroy nesting habitat for endangered species. Warming temperatures in the Arctic allow beavers to extend their habitat further north, where their dams impair boat travel, impact access to food, affect water quality, and endanger downstream fish populations. Pools formed by

2604-663: Is the family, which is composed of an adult male and an adult female in a monogamous pair and their offspring. Beaver families can have as many as ten members; groups about this size require multiple lodges. Mutual grooming and play fighting maintain bonds between family members, and aggression between them is uncommon. Adult beavers mate with their partners, though partner replacement appears to be common. A beaver that loses its partner will wait for another one to come by. Estrus cycles begin in late December and peak in mid-January. Females may have two to four estrus cycles per season, each lasting 12–24 hours. The pair typically mate in

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2688-489: Is the source for several European placenames , including those of Beverley , Bièvres , Biberbach , Biebrich , Bibra , Bibern , Bibrka , Bobr , Bober , Bóbrka , Bjurholm , Bjurälven , and Bjurum . The genus name Castor has its origin in the Greek word κάστωρ kastōr and translates as ' beaver ' . Carl Linnaeus coined the genus name Castor in 1758 as well as the specific (species) epithet fiber for

2772-645: The IUCN Red List of mammals. In human culture, the beaver symbolizes industriousness, especially in connection with construction; it is the national animal of Canada. The English word beaver comes from the Old English word beofor or befor and is connected to the German word biber and the Dutch word bever . The ultimate origin of the word is an Indo-European root for ' brown ' . Cognates of beaver

2856-694: The North American beaver ( Castor canadensis ) and the Eurasian beaver ( C. fiber ). The Eurasian beaver is slightly longer and has a more lengthened skull, triangular nasal cavities (as opposed to the square ones of the North American species), a lighter fur color, and a narrower tail. Agnotocastor coloradensis Agnotocastor praetereadens Anchitheriomys sp. [REDACTED] Castorinae (modern beavers) [REDACTED] Castoroidinae [REDACTED] Agnotocastor sp. Migmacastor procumbodens Palaeocastorinae [REDACTED] Heteromyidae (kangaroo rats and allies) [REDACTED] Geomyidae (gophers) [REDACTED] Beavers belong to

2940-627: The Scandinavian Peninsula . Beginning in 2009, beavers have been successfully reintroduced to parts of Great Britain. In 2020 , the total Eurasian beaver population in Europe was estimated at over one million. Small native populations are also present in Mongolia and northwestern China; their numbers were estimated at 150 and 700, respectively, as of 2016 . Under New Zealand's Hazardous Substances and New Organisms Act 1996 , beavers are classed as

3024-401: The ecosystem , beavers are considered a keystone species . Adult males and females live in monogamous pairs with their offspring. After their first year, the young help their parents repair dams and lodges; older siblings may also help raise newly born offspring. Beavers hold territories and mark them using scent mounds made of mud, debris, and castoreum —a liquid substance excreted through

3108-1035: The riparian zone associated with beaver dams has been shown to increase the abundance and diversity of birds favoring the water's edge, an impact that may be especially important in semi-arid climates . Fish-eating birds use beaver ponds for foraging, and in some areas, certain species appear more frequently at sites where beavers were active than at sites with no beaver activity. In a study of Wyoming streams and rivers, watercourses with beavers had 75 times as many ducks as those without. As trees are drowned by rising beaver impoundments, they become an ideal habitat for woodpeckers , which carve cavities that may be later used by other bird species. Beaver-caused ice thawing in northern latitudes allows Canada geese to nest earlier. Other semi-aquatic mammals, such as water voles , muskrats , minks , and otters , will shelter in beaver lodges. Beaver modifications to streams in Poland create habitats favorable to bat species that forage at

3192-748: The surname Beever . If an internal link intending to refer to a specific person led you to this page, you may wish to change that link by adding the person's given name (s) to the link. v t e Family names derived from the word " beaver " Germanic Beaver , Beavers , Beever , Beevers , Beber , De Bever , Bever, Biber , Bieber , Biebl [REDACTED] Slavic Bober , Bóbr , Bobrov , Bobyor Retrieved from " https://en.wikipedia.org/w/index.php?title=Beever&oldid=1082637267 " Categories : Surnames Surnames from nicknames Hidden categories: Articles with short description Short description

3276-461: The water table in wetlands such as peatlands , they can stabilize a fluctuating water table, which influences the levels of both carbon and water. In a 2017 study of beaver dam hydrology, monitored beaver dams in a Rocky Mountain peatland were found to increase groundwater storage and regional water balance , which can be beneficial for preventing drought. The study also suggested potential to improve carbon sequestration . Beaver ponds can cause

3360-593: The Eurasian species. German zoologist Heinrich Kuhl coined C. canadensis in 1820, many scientists considered both names synonymous for one same species until the 1970s, when chromosomal evidence became available confirming both as separate where the Eurasian has 48 chromosomes, while the North American has 40.) The difference in chromosome numbers prevents them from interbreeding. Twenty-five subspecies have been classified for C. canadensis , and nine have been classified for C. fiber . There are two extant species:

3444-488: The animal warm, to help it float in water, and to protect it against predators. Guard hairs are 5–6 cm (2.0–2.4 in) long and typically reddish brown, but can range from yellowish brown to nearly black. The underfur is 2–3 cm (0.79–1.18 in) long and dark gray. Beavers molt every summer. Beavers have large skulls with powerful chewing muscles . They have four chisel-shaped incisors that continue to grow throughout their lives. The incisors are covered in

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3528-558: The average size of these fishes. These species use beaver habitats for spawning, overwintering, feeding, and as havens from changes in water flow. The positive effects of beaver dams on fish appear to outweigh the negative effects, such as blocking of migration. Beaver ponds have been shown to be beneficial to frog populations by protecting areas for larvae to mature in warm water. The stable waters of beaver ponds also provide ideal habitat for freshwater turtles . Beavers help waterfowl by creating increased areas of water. The widening of

3612-475: The beaver dam flows more slowly into the stream. This may also help in reducing flood waves, and increasing water flow when there is no rain. In other words, beaver dams smooth out water flow by increasing the area wetted by the stream. This allows more water to seep into the ground where its flow is slowed. This water eventually finds its way back to the stream. Rivers with beaver dams in their head waters have lower high water and higher low water levels. By raising

3696-415: The beaver include the bacteria Francisella tularensis , which causes tularemia ; the protozoan Giardia duodenalis , which causes giardiasis (beaver fever); and the beaver beetle and mites of the genus Schizocarpus . They have also been recorded to be infected with the rabies virus . Beavers need trees and shrubs to use as building material for dams , which restrict flowing water to create

3780-571: The beaver is relatively poor; the beaver eye cannot see as well underwater as an otter . Beavers have a good sense of smell, which they use for detecting land predators and for inspecting scent marks, food, and other individuals. Beavers can hold their breath for as long as 15 minutes but typically remain underwater for no more than five or six minutes. Dives typically last less than 30 seconds and are usually no more than 1 m (3 ft 3 in) deep. When diving, their heart rate decreases to 60 beats per minute, half its normal pace, and blood flow

3864-400: The beaver population on the continent to rebound to an estimated 6–12   million by the late 20th century; still far lower than the originally estimated 60–400   million North American beavers before the fur trade. The introduced population in Tierra del Fuego is estimated at 35,000–50,000 individuals as of 2016 . The Eurasian beaver's range historically included much of Eurasia, but

3948-571: The beaver's urethra -based castor sacs. Beavers can also recognize their kin by their anal gland secretions and are more likely to tolerate them as neighbors. Historically, beavers have been hunted for their fur, meat, and castoreum. Castoreum has been used in medicine, perfume, and food flavoring; beaver pelts have been a major driver of the fur trade . Before protections began in the 19th and early 20th centuries, overhunting had nearly exterminated both species. Their populations have since rebounded, and they are listed as species of least concern by

4032-442: The body, and the male's penis has a cartilaginous baculum . They have only one opening, a cloaca , which is used for reproduction, scent-marking, defecation, and urination. The cloaca evolved secondarily, as most mammals have lost this feature, and may reduce the area vulnerable to infection in dirty water. The beaver's intestine is six times longer than its body, and the caecum is double the volume of its stomach. Microorganisms in

4116-551: The bottom widens. Research is sparse, but it seems likely that parts of the bottomland in North America was created, or at least added to, by the efforts of the generations of beavers that lived there. Humans sometimes build structures similar to beaver dams in streams, either to get the benefits of beaver dams in places without beavers, or to encourage beavers to settle in a particular area. These are often called "beaver dam analogs" (BDA) although other names are also used. When

4200-402: The breakdown of toxins such as pesticides and the retention of silt by beaver dams. Beaver dams reduce erosion and decrease the turbidity that can be a limiting factor for some aquatic life. The benefits may be long-term and largely unnoticed unless a catchment is monitored closely. Almost half of endangered and threatened species in North America rely upon wetlands. In 2012, a systematic review

4284-404: The caecum allow them to process around 30 percent of the cellulose they eat. A beaver defecates in the water, leaving behind balls of sawdust. Female beavers have four mammary glands ; these produce milk with 19 percent fat, a higher fat content than other rodents. Beavers have two pairs of glands: castor sacs, which are part of the urethra, and anal glands . The castor sacs secrete castoreum ,

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4368-529: The common ancestor of the two living species at around 8 mya. The ancestors of the North American beaver would have crossed the Bering Land Bridge around 7.5 mya. Castor may have competed with members of Castoroidinae, which led to niche differentiation . The fossil species C. praefiber was likely an ancestor of the Eurasian beaver. C. californicus from the Early Pleistocene of North America

4452-431: The constantly changing water levels, leading to greater carbon storage . Beaver ponds, and the wetlands that succeed them, remove sediments and pollutants from waterways, and can stop the loss of important soils. These ponds can increase the productivity of freshwater ecosystems by accumulating nitrogen in sediments. Beaver activity can affect the temperature of the water; in northern latitudes, ice thaws earlier in

4536-406: The dams store heat, thus changing local hydrology and causing localized thawing of permafrost that in turn contributes to global warming. If a beaver pond becomes too shallow due to sediment accumulation, or the tree supply is depleted, beavers will abandon the site. Eventually the dam will be breached and the water will drain out. The rich thick layer of silt, branches, and dead leaves behind

4620-404: The factors associated with the decline of salmon runs were extant at that time. There are several reasons why beaver dams increase salmon runs. They produce ponds that are deep enough for juvenile salmon to hide from predatory wading birds . They trap nutrients in their ecology and notably the nutrient pulse represented by the migration of the adult salmon upstream. These nutrients help feed

4704-412: The flooding occurs next to a railroad roadbed, it can cause derailments by washing out the tracks. When a beaver dam bursts , the resulting flash flood may overwhelm a culvert . Traditional solutions to beaver problems have been focused on the trapping and removal of all the beavers in the area. While this is sometimes necessary, it is typically a short-lived solution, as beaver populations have made

4788-487: The goal is to attract beavers, sometimes the site is unsuitable in its present condition, such as being too eroded for beavers to build a dam in their usual way. BDA builders may use construction techniques beyond the beaver's capabilities, such as driving wooden posts into the stream bed to brace horizontal branches that would otherwise be washed away. The hope is that beavers who wander by or are brought in will choose to live there and take over construction and maintenance of

4872-406: The growth of adventitious roots. Finally the meadow will be colonized by riverine trees, typically aspens, willows and such species which are favoured by the beaver. Beavers are then likely to recolonize the area, and the cycle begins again. Each time the stream life cycle repeats itself another layer of organic soil is added to the bottom of the valley. The valley slowly fills and the flat area at

4956-444: The growth of species of plants that are critical to populations of songbirds in decline, beaver dams help create food and habitat. The presence of beaver dams has been shown to be associated with an increased diversity of songbirds. They can also have positive effects on local waterfowl, such as ducks, that are in need of standing water habitats. Beaver dams can be disruptive; the flooding can cause extensive property damage, and, when

5040-762: The indigenous forest. Unlike trees in North America, many trees in South America cannot grow back after being cut down. Beaver activity impacts communities of aquatic invertebrates . Damming typically leads to an increase of slow or motionless water species, like dragonflies , oligochaetes , snails , and mussels . This is to the detriment of rapid water species like black flies , stoneflies , and net-spinning caddisflies . Beaver floodings create more dead trees, providing more habitat for terrestrial invertebrates like Drosophila flies and bark beetles , which live and breed in dead wood. The presence of beavers can increase wild salmon and trout populations, and

5124-864: The juveniles after the yolk sac has been digested. The dams provide calm water which means that the young salmon can use energy for growth rather than for navigating currents; larger smolts with a food reserve have a better rate of survival when they reach the sea. Finally, beaver dams keep the water clear which favours all salmonoids . Beaver dams have been shown to be beneficial to frog and toad populations, likely because they provide protected areas for larvae to mature in warmer, well-oxygenated water. A study in Alberta, Canada, showed that "Pitfall traps on beaver ponds captured 5.7 times more newly metamorphosed wood frogs, 29 times more western toads and 24 times more boreal chorus frogs than on nearby free-flowing streams." Beaver dams help migrating songbirds . By stimulating

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5208-435: The lodge and/or food cache. As they drag wood across the land, beavers leave behind trails or "slides", which they reuse when moving new material. The beaver works as an ecosystem engineer and keystone species , as its activities can have a great impact on the landscape and biodiversity of an area. Aside from humans, few other extant animals appear to do more to shape their environment. When building dams, beavers alter

5292-535: The lodge, according to a 2004–2012 study that mapped beaver ponds and cut stumps. Some people consider that by building dams beavers are expressing tool use behaviour. Beaver dams typically range in length from a few meters to about 100 metres (330 ft). Canals can be over 0.5 kilometres (1,600 ft) long. The largest known beaver dam is in Wood Buffalo National Park in Alberta , Canada, and

5376-567: The next decade. Coordinates: 58°16′15″N 112°15′6″W  /  58.27083°N 112.25167°W  / 58.27083; -112.25167 . Another large beaver dam measuring 2,139 feet (650 m) long, 14 feet (4.3 m) high and 23 feet (7.0 m) thick at the base was found in Three Forks, Montana . Dam building can help to restore damaged wetlands. Wetland benefits include flood control downstream, biodiversity (by providing habitat for different species), and water cleansing, both by

5460-453: The old dam is an ideal habitat for some wetland species. As the wetland fills up with plant debris and dries out, pasture species colonize it and the wetland may eventually become a meadow suitable for grazing in a previously forested area. This provides a valuable niche for many animals which otherwise would be excluded. Beaver dam creation also increases the plants the dams were made from (such as willows) to reproduce by cutting , encouraging

5544-466: The paths of streams and rivers, allowing for the creation of extensive wetland habitats. In one study, beavers were associated with large increases in open-water areas. When beavers returned to an area, 160% more open water was available during droughts than in previous years, when they were absent. Beaver dams also lead to higher water tables in mineral soil environments and in wetlands such as peatlands . In peatlands particularly, their dams stabilize

5628-404: The presence of a third set of premolars (P3), a hole in the stapes of the inner ear, a smooth palatine bone (with the palatine opening closer to the rear end of the bone), and a longer snout . More derived castorids have less complex occlusion, upper tooth rows that create a V-shape towards the back, larger second premolars compared to molars, absence of a third premolar set and stapes hole,

5712-400: The removal of nutrients from the stream flow. Farming along the banks of rivers often increases the loads of phosphates, nitrates and other nutrients, which can cause eutrophication and may contaminate drinking water. Besides silt, the beaver dam collects twigs and branches from the beavers' activity as well as leaves, notably in the autumn . The main component of this material is cellulose ,

5796-651: The rest of the body is submerged. The nostrils and ears have valves that close underwater, while nictitating membranes cover the eyes. To protect the larynx and trachea from water flow, the epiglottis is contained within the nasal cavity instead of the throat. In addition, the back of the tongue can rise and create a waterproof seal. A beaver's lips can close behind the incisors, preventing water from entering their mouths as they cut and bite onto things while submerged. The beaver's front feet are dexterous, allowing them to grasp and manipulate objects and food, as well as dig. The hind feet are larger and have webbing between

5880-760: The rodent suborder Castorimorpha , along with Heteromyidae ( kangaroo rats and kangaroo mice ), and the gophers . Modern beavers are the only extant members of the family Castoridae . They originated in North America in the late Eocene and colonized Eurasia via the Bering Land Bridge in the early Oligocene , coinciding with the Grande Coupure , a time of significant changes in animal species around 33   million years ago ( myr ). The more basal castorids had several unique features: more complex occlusion between cheek teeth, parallel rows of upper teeth, premolars that were only slightly smaller than molars,

5964-677: The shore and covered in sticks. The more complex freestanding, open-water lodges are built over a platform of piled-up sticks. The lodge is mostly sealed with mud, except for a hole at the top which acts as an air vent. Both types are accessed by underwater entrances. The above-water space inside the lodge is known as the "living chamber", and a "dining area" may exist close to the water entrance. Families routinely clean out old plant material and bring in new material. North American beavers build more open-water lodges than Eurasian beavers. Beaver lodges built by new settlers are typically small and sloppy. More experienced families can build structures with

6048-412: The superstructure. Beavers can transport their own weight in material; they drag logs along mudslides and float them through canals to get them in place. Once the dam has flooded enough area to the proper depth to form a protective moat for the lodge (often covering many acres), beavers begin construction of the lodge. Trees approaching a diameter of 90 centimetres (3.0 ft) may be used to construct

6132-496: The toes , and the second innermost toe has a "double nail" used for grooming. Beavers can swim at 8 km/h (5.0 mph); only their webbed hind feet are used to swim, while the front feet fold under the chest. On the surface, the hind limbs thrust one after the other; while underwater, they move at the same time. Beavers are awkward on land but can move quickly when they feel threatened. They can carry objects while walking on their hind legs. The beaver's distinctive tail has

6216-512: The warmer beaver-dammed waters. Beavers may contribute to climate change . In Arctic areas, the floods they create can cause permafrost to thaw, releasing methane into the atmosphere . As wetlands are formed and riparian habitats are enlarged, aquatic plants colonize the newly available watery habitat. One study in the Adirondacks found that beaver engineering lead to an increase of more than 33 percent in herbaceous plant diversity along

6300-420: The water and to a lesser extent in the lodge, for half a minute to three minutes. Up to four young, or kits, are born in spring and summer, after a three or four-month gestation . Newborn beavers are precocial with a full fur coat, and can open their eyes within days of birth. Their mother is the primary caretaker, while their father maintains the territory. Older siblings from a previous litter also play

6384-457: The water stream and keep these and other nutrients in the beaver pond and the surrounding ecology. Agriculture introduces herbicides and pesticides into streams. Some of these toxicants are metabolized and decomposed by the bacteria in the cellulose-rich bottom of a beaver dam. Some scientists believe that the nitrogen cascade , the production of more fixed nitrogen than the natural cycles can turn back into nitrogen gas, may be as much of

6468-548: The water surface and "prefer moderate vegetation clutter". Large herbivores, such as some deer species, benefit from beaver activity as they can access vegetation from fallen trees and ponds. Beavers are mainly nocturnal and crepuscular , and spend the daytime in their shelters. In northern latitudes, beaver activity is decoupled from the 24-hour cycle during the winter, and may last as long as 29 hours. They do not hibernate during winter, and spend much of their time in their lodges. The core of beaver social organization

6552-524: The water's edge. Another study in semiarid eastern Oregon found that the width of riparian vegetation on stream banks increased several-fold as beaver dams watered previously dry terraces adjacent to the stream. Riparian ecosystems in arid areas appear to sustain more plant life when beaver dams are present. Beaver ponds act as a refuge for riverbank plants during wildfires , and provide them with enough moisture to resist such fires. Introduced beavers at Tierra del Fuego have been responsible for destroying

6636-546: The water, but will roam several hundred meters to find more. Beavers have also been recorded in mountainous areas. Dispersing beavers will use certain habitats temporarily before finding their ideal home. These include small streams, temporary swamps, ditches, and backyards. These sites lack important resources, so the animals do not stay there permanently. Beavers have increasingly settled at or near human-made environments, including agricultural areas, suburbs , golf courses , and shopping malls. Beavers have an herbivorous and

6720-499: Was conducted on the impacts of beaver dams on fishes and fish habitat (biased to North America (88%)). The most frequently cited benefits of beaver dams were increased habitat heterogeneity , rearing and overwintering habitat, flow refuge, and invertebrate production. Impeded fish movement because of dams, siltation of spawning habitat and low oxygen levels in ponds were the most often cited negative impacts. Benefits (184) were cited more frequently than costs (119). A beaver dam may have

6804-835: Was decimated by hunting by the early 20th century. In Europe, beavers were reduced to fragmented populations, with combined population numbers being estimated at 1,200 individuals for the Rhône of France, the Elbe in Germany, southern Norway, the Neman river and Dnieper Basin in Belarus, and the Voronezh river in Russia. The beaver has since recolonized parts of its former range, aided by conservation policies and reintroductions . Beaver populations now range across western, central, and eastern Europe, and western Russia and

6888-451: Was introduced to Finland in 1937 (and then spread to northwestern Russia) and to Tierra del Fuego, Patagonia , in 1946. As of 2019 , the introduced population of North American beavers in Finland has been moving closer to the habitat of the Eurasian beaver. Historically, the North American beaver was trapped and nearly extirpated because its fur was highly sought after. Protections have allowed

6972-511: Was seen following the 1818 agreement between the British government of Canada and the government of America allowing Americans access to the Columbia watershed. The Hudson's Bay Company , in a fit of pique, instructed its trappers to extirpate the fur-bearing animals in the area. The beaver was the first to be made locally extinct. Salmon runs fell precipitously in the following years, even though none of

7056-651: Was similar to but larger than the extant North American beaver. ' Beavers are the second-largest living rodents, after capybaras . They have a head–body length of 80–120 cm (31–47 in), with a 25–50 cm (9.8–19.7 in) tail, a shoulder height of 30–60 cm (12–24 in), and generally weigh 11–30 kg (24–66 lb), but can be as heavy as 50 kg (110 lb). Males and females are almost identical externally. Their bodies are streamlined like marine mammals and their robust build allows them to pull heavy loads. A beaver coat has 12,000–23,000 hairs/cm (77,000–148,000 hairs/in ) and functions to keep

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