The BEAVER is a Busy Little Animal
Beavers are large rodents and one of the few species that significantly modify their environment. They build watertight dams that reduce stream erosion, form slow-moving ponds and provide aquatic habitat for dozens of other species.
Physical Description
North American beavers are a common type of rodent that has a yellow-brown to black coat with webbed rear feet and large incisors that grow continuously. They also have digitated front paws.
Beaver’s teeth grow throughout their lives and they’re able to cut through objects with a single bite. Sharp, dark-orange incisors are visible in the beaver’s mouth, and they’re self-sharpening. If a beaver’s incisors get too long, they can cause their mouth to be too low and prevent grinding. If this happens, the animal may starve to death.
Beavers often change from aquatic to terrestrial environments. Their front paws, which are small and dexterous, make them well suited for working on the land. They walk on five digits, have hands with specialized front paws that can grasp sticks, and dig into the ground. They also have well-developed webbed hind feet for swimming and no fur on the dorsal surface.
The hind feet have a special preening toe. The second toe on the inside has two toenails that are unique among mammals. In fact, beavers are prolific groomers and will regularly take mud baths in order to improve their coat condition as well as stay healthy internally by bathing off parasites and germs from outside.
They use the preening foot as a comb to prevent their fine and delicate fur from matting. This also helps with the waterproofing and insulating properties of the fur. They do this by removing burrs and parasites with their flexible feet.
On land, beavers move in an awkward way and are vulnerable to predators. However, in the water, they swim at up to 10 km/h (6 mph) and can stay there for up to 15 minutes while they make their way over long distances.
Beavers use their whiskers to help them feel their way around in the dark & they have a transparent membrane, called a “nictitating membrane”, that covers the eye when underwater. A beaver has a poor sense of vision, but its hearing is very good. Its ears are external, small, and rounded; they close while the beaver’s submerged (which helps to explain how it survives in water).
The length and shape of the tail are controlled by genes and differ from fox to fox. The tail is devoid of hair, covered in black scales, and demarcated sharply from surrounding fur. There is only a very small amount of fur that often surrounds the tip of the tail. The tail is used as a rudder in swimming, as a balanced prop when working on land and to signal danger when it is slapped on the water. The ears help to pick up sounds such as when it listens for prey.
The tusks of the walrus are sharp and used for fighting, stabbing, and ripping flesh from the prey, scraping ice from rocks, or breaking apart seals. Beavers often store a lot of fat in their tails, which they then use for food during the winter. This enables them to survive even if food is unavailable at this time. The beaver’s vertebrae then keep on going and end near the end of the tail.”
Size
North American beavers are the largest rodents in North America and the second-largest in the world (South America’s capybaras being the heaviest) — they weigh between 35-65 pounds (16-30 kilograms) with the heaviest being about 72 pounds.
The size of the beaver ranges between 3-4 feet (1-1.2 meters) in length and 1 to 1.5 feet (0.3 to 0.5 meters) in height, with tails that vary but are usually around 2 inches thick at the base and taper to less than a quarter-inch in thickness (less than 0.6 centimeters).
Native Habitat
Beavers are not found in the desert areas of California, Nevada, and parts of Utah and Arizona. They inhabit lakes, ponds, rivers, and streams throughout North America.
Beavers are one of the few animals that can modify their habitat, they build dams using sticks, reeds, branches, and saplings. The dams slow down streams to form ponds which help to reduce erosion. These ponds provide a habitat for small aquatic life and larger animals. By building dams, beavers create new habitats that can support a diverse community of life forms.
Beavers build dome-like lodges which rise up to 2m. Sometimes they have one or more underwater entrances and living quarters are near the top so they don’t get flooded. Underwater hotels are quite luxurious and often built a long way from the shore.
There are currently 10 underwater hotel lodges in 6 different countries, all with the same luxury features. The size of each room is on average 4 by 2 feet (3’6″ x 1′) but they do vary slightly. They are insulated with walls 1 & 1/3rd meters thick, and the roof is covered with .8 meters of soil.
The main building has a hipped and gable roof, but the neighboring buildings have more simple pitched roofs. The walls are constructed of large, red bricks up to 1 meter thick. They were originally whitewashed but now are faded with gray stains from decades in the desert sun. Beavers dry the inside of their lodges by building dams & collecting food for the winter. They lay down wood shavings to absorb excess moisture within the den.
Communication
One important signal that beavers use to communicate danger is a tail slap. They typically should it when they’re in deep water, and it warns the others to do the same. However, they may also use it as a means of frightening predators away.
Beaver families live in their own territory, but they communicate with other beaver families by leaving scents near the borders of their territory. Beavers are among the few rodents that build scent mounds. The pile, often composed of mud, sticks, and grass and usually one-third of a meter high and about 1 meter wide, is used by beavers to deposit scents from their anal glands.
Beavers have an organ, called a castor sac, near their bottom. They use this organ to produce a thick liquid secretion to mark their territory and leave behind an unpleasant smell (castor). The oil glands produce a waterproofing substance for the fur that is different between both males and females. The oil is also used in reproductive communication.
Beavers’ vocalizations & postures are what they use to communicate with each other. For example, at the Smithsonian’s National Zoo in Washington DC, when beavers are unhappy they occasionally hiss.
Food/Eating Habits
Beavers are herbivores, and their most common food is plant material. This includes leaves, woody stems, and aquatic plants.
White-tailed deer tend to do the bulk of their feeding in the late summer and early fall because of limited sources to eat during winter. In winter, they will block up a spot on the pond or wet area with rushes and branches, then return there during warmer weather to feed.
The water acts as a refrigerator, maintaining the food’s coldness and preserving its nutritional value. Beavers hold their food with their front paws and eat corn-on-the-cob style, using their incisors to crush the kernels and their stomachs to digest them.
Beavers are not reclusive animals but are very sociable when they need to eat or drink. They often spend time near water because they drink from it, swim in it on hot days, and occasionally fall into it during hibernation.
Although beavers build dams for a variety of reasons, they often build dams to keep their food safe and protected. Beavers build dams that are less than a foot high and maybe either be natural or constructed. A natural dam is made with mud, wood, sticks, and stones available on the creek bed or pond.
The Smithsonian National Zoo feeds their animal’s mixed vegetables, rodent chow, leafy greens, and a healthy supply of wood chips. Rabbit, alpaca, and llama hay; goat show; pig swill; chicken feed supplemented with greens, fruit, and veggies. Wood chips for all animals in the zoo.
Social Structure
Beavers are social animals. They form tight-knit families consisting of one breeding pair and the year’s kits. Sometimes older sub-adult birds, who are 2 or older, may stay behind. These sub-adults generally will not breed again.
In winter, these family groups live in their lodge and share food from the common larder. The hierarchy in this family is clear and stable, with the adults dominating yearlings, and the yearlings dominating kits. The members of this family communicate about issues using vocalizations, gestures, and postures rather than physical aggression.
Reproduction and Development
Our understanding is that beavers are monogamous. They mate from January to late February and females give birth in the spring.
Kits are born (approximately) 1lbs. and can take to the water in less than 30mins after birth. By the end of their first week, they are skilled swimmers, but because they are so buoyant, it may take them a little longer to get the hang of diving (if they ever do).
Kits typically spend the first few weeks of their lives staying close to their mother in the lodge and nursing a lot to gain weight. Female bears have four nipples that they sometimes use while they are nursing. There is evidence of sibling littermates sharing teats, which may explain how all the pups in the family are able to survive. Kits nurse for about 6 weeks and members of the family share in bringing food to them.
Mothers often carry their kits while they are on land, sometimes even walking and holding them in their paws. In the water, kits may rest on their mother’s back. Cubs remain with their parents for about two years and help with chores around the lodge until they are driven away shortly before their sibling is born.
Sleep Habits
For most of the year, beavers are active during the night. But in areas where winter lasts all year, the beaver will stay in its lodge or under a frozen pond, eating what it has gathered and relying on its fat reserves to survive.
Beavers in a lodge or underwater environment do not experience periods of day & night due to their low lighting, which is consistent across the course of a day. This does not allow for sunrise or sunset, nor does it sync their movement patterns with the solar day. The circadian rhythm or regular day cycle of a beaver changes overnight and this affects the days, which range from between 26 to 29 hours. Beavers wake up in the early evening, around 4 pm at the zoo for example.
Lifespan
North American beavers typically live 10 to 12 years. The oldest in captivity lived 30 years of age. In the United States, beavers are currently listed as endangered. As of June 2018, there were 2,000 beavers living in Montana. The American beaver is currently listed as an endangered species in Montana, where they were reintroduced by the state. In North America, their range has shrunk over the past century, leading to them having few remaining locations for habitat.
The United States Fish and Wildlife Service has classified beavers as threatened throughout much of their range and considered them endangered in Canada. The population has been steadily increasing since 2009 when the last reported sighting was made in the state. Beaver populations have also been reintroduced to Central Park and Yosemite National Park since 2006. The IUCN is currently evaluating the beaver’s conservation status.
Although there are still concerns about their effects on water quality and vegetation, other factors such as climate change and habitat loss have led to a possible reclassification in the near future. In general, they are considered an important keystone species able to cycle nutrients in aquatic ecosystems, affecting other species in a positive way.” Pseudochromis Fridman” is an important reef dweller, and one of the most common fish species in the Red Sea. Other important ichthyofauna species include “Synodontis gayi”, “Puntius conchonius”, “Telmatherina ladies”, and “Carangoides arcuatus”.
Major threats to the wetland include agricultural and grazing activities, uncontrolled development of dry-land salinity, construction of canals, and aquaculture by-products. The wetland also is a target for groundwater abstraction by the rapidly expanding coastal city of Haifa. Because it is so close to the Mediterranean Sea, the water table is relatively shallow.
