Interesting Creatures… Muskrat (Ondatra zibethicus)

Jan 05, 2020 Interesting Creatures in Guyana, News

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The muskrat (Ondatra zibethicus), the only species in genus Ondatra and tribe Ondatrini, is a medium-sized semi-aquatic rodent native to North America and an introduced species in parts of Europe, Asia, and South America.

The muskrat is found in wetlands over a wide range of climates and habitats. It has important effects on the ecology of wetlands, and is a resource of food and fur for humans. It is the largest species in the subfamily Arvicolinae, which includes 142 other species of rodents, mostly 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, however, members of the genus Rattus.
The muskrat’s name probably comes from a word of Algonquian (possibly Powhatan) origin, muscascus (literally “it is red”, so called for its colourings), 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” odour, which the muskrat uses to mark its territory, and its flattened tail, the name became altered to musk-beaver; later it became “muskrat” due to its resemblance to rats.
Similarly, its specific name zibethicus means “musky”, being the adjective of zibethus “civet musk; civet”. The genus name comes from the Huron word for the animal, ondathra, and entered New Latin as Ondatra via French.
An adult muskrat is about 40–70 cm (16–28 in) long, half of that is the tail, and weighs from 0.6–2 kg (1.3–4.4 lb). That is about four times the weight of the brown rat (Rattus norvegicus), though an adult muskrat is only slightly longer, and are almost certainly the largest and heaviest members of the diverse family Cricetidae, which includes all voles, lemmings, and most mice native to the Americas.
Muskrats are much smaller than beavers (Castor canadensis), with which they often share their habitat.
Muskrats are covered with short, thick fur, which is medium to dark brown or black in colour, with the belly a bit lighter (countershaded); as the age increases, it turns a partly grey in colour. The fur has two layers, which help protect them from the cold water.
They have long tails covered with scales rather than hair, and to aid them in swimming, are slightly flattened vertically, which is a shape that is unique to them. When they walk on land, their tails drag on the ground, which makes their tracks easy to recognize.
Muskrats spend most of their time in the water and are well suited for their semi-aquatic 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 semi-webbed, although in swimming, their tails are their main means of propulsion.
Muskrats are found over most of Canada and 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 mostly inhabit wetlands, areas in or near saline and freshwater wetlands, rivers, lakes, or ponds. They are not found in Florida, where the round-tailed muskrat, or Florida water rat (Neofiber alleni), fills their ecological niche.
Their populations naturally cycle; in areas where they become abundant, they are capable of removing much of the vegetation in wetlands. They are thought to play a major role in determining the vegetation of prairie wetlands in particular. They also selectively remove preferred plant species, thereby changing the abundance of plant species in many kinds of wetlands.
Species commonly eaten include cattail and yellow water lily. Alligators are thought to be an important natural predator, and 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, and the muskrat remains common and widespread. They are able to live alongside streams which contain the sulphurous water that drains away from coal mines. Fish and frogs perish in such streams, yet muskrats may thrive and occupy the wetlands. Muskrats also benefit from human persecution of some of their predators.
They normally live in groups consisting of a male and female pair and their young. During the spring, they often fight with each other over territory and potential mates. Many are injured or killed in these fights.
Muskrats provide an important food resource for many other animals, including mink, foxes, coyotes, wolves, lynx, bobcats, bears, eagles, snakes, alligators, and large owls and hawks. Otters, snapping turtles, and large fish such as pike prey on baby muskrats.
Muskrats, like most rodents, are prolific breeders. Females can have two or three litters a year of six to eight young each. The babies are born small and hairless, and weigh only about 22 g (0.78 oz). In southern environments, young muskrats mature in six months, while in colder northern environments, it takes about a year.
Muskrat populations appear to go through a regular pattern of rise and dramatic decline spread over a six- to 10-year period. Some other rodents, including famously the muskrat’s close relatives the lemmings, go through the same type of population changes. [Source: Wikipedia]

 

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