Devoir de Philosophie

Fox (animal) - biology.

Publié le 11/05/2013

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Fox (animal) - biology. I INTRODUCTION Fox (animal), smallest member of the dog family, which also includes wolves, coyotes, jackals, and dogs. Foxes are characterized by short legs, an elongated narrow muzzle, erect triangular ears, thick fur, and a long bushy tail. Foxes are found throughout the Americas, Eurasia, and Africa, inhabiting mostly forest, chaparral, and desert regions. Most of the ten species of the genus to which the red fox belongs can adapt to diverse climates and habitats. Most foxes feed on mice, voles, rabbits, birds' eggs, fruit, large insects, and carrion. Because their prey is small, foxes are solitary rather than pack hunters. They generally work territories of less than 8 sq km (less than 3 sq mi), which they defend from other foxes. They are swift, agile runners; the red fox can reach a speed of 48 km/h (30 mph). II THE RED FOX The red fox is by far the most common species of fox. It is 90 to 105 cm (36 to 42 in) long, not including the tail, weighs about 7 kg (about 15 lb), and is distinguished by black ears and feet and a white tip on the tail. The coat is usually some shade of rusty-red or reddish-brown, sprinkled with light-tipped hairs. The red fox ranges across Eurasia and North Africa and from northern Mexico to the Arctic. Within these vast zones diverse variations of the red fox have developed; those of the south are smaller and have lighter-colored coats, and those of the north are larger, with thicker and darker coats. The silver fox, valued for its black, frosted fur, is simply a variant of the red fox. The great alertness of the red fox, and its keen senses of smell, hearing, and sight, enable it to live close to human habitation without being easily noticed. Farmland with woodlots and open fields provides it with good cover and abundant rodents, especially field mice. When red foxes have been eradicated from rural areas, populations of rodents have swelled. Red foxes were introduced to Australia to cope with its plague of previously introduced rabbits. On pairing, red foxes occupy a territory of 3 to 8 sq km (1.5 to 3 sq mi). They mate in midwinter, and following a 49- to 56-day gestation period, the vixen bears two to eight cubs in a den that is frequently an enlarged groundhog hole. The cubs are born with their eyes closed and are attended in the den by both parents for about five weeks. By fall the young leave or are driven from the territory. Red foxes are believed to pair for life; their lifespan is about 12 years. III OTHER FOXES The gray fox is a little smaller than the red fox, and its coat of coarse, pepper-and-salt gray hair is of far less commercial value. It ranges from southern Canada to northern South America and inhabits mostly forests and arid bush country. Gray foxes are the only members of the dog family known to climb trees. The swift fox is a shy, fast-running, nocturnal animal that lives in the Great Plains of southern Canada and the northern United States. Only about two-thirds the size of the red fox, the swift fox is also called a kit fox. Another small fox, the long-eared kit fox, lives in arid regions of the southwestern United States and northern Mexico. Foxes that live in similarly arid habitats include the cape fox of South Africa, Ruppell's sand fox of the Sahara Desert, and the fennec--all of which have dense, sandcolored fur to protect them from extreme temperatures. Their long ears are believed useful in dispersing heat. The arctic fox ranges throughout the Arctic and is often found on ice fields that may be hundreds of kilometers from the mainland. Its coat is white in winter and brown in summer. A small percentage of arctic foxes, especially those in Greenland, are blue, changing from dark bluish-gray in summer to a pale bluish-gray in winter. Arctic foxes, like other species, do not hibernate but remain active, eating whale carrion, scraps left from polar bear kills, and possibly young seals. The ears of arctic foxes are short, heavily furred, and rounded, thus limiting the dispersal of heat. Scientific classification: Foxes belong to the family Canidae. The red fox is classified as Vulpes vulpes, and the gray fox as Urocyon cinereoargenteus. The swift fox is classified as Vulpes velox, the long-eared kit fox as Vulpes macrotis, and the cape fox as Vulpes chama. Ruppell's sand fox is classified as Vulpes rueppellii, the fennec as Vulpes zerda, and the arctic fox as Alopex lagopus. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.

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