Wild yak


The wild yak includes a dense undercoat of soppy, close-matted hair that is roofed by typically dark brown to black outer hair. Its long, shaggy coat reaches virtually to the bottom. The wild yak will weigh up to one thousand metric weight unit (2200 lb) with a shoulder height of over a pair of m (6.5'). It happens in unforested uplands, as well as plains, hills, and mountains, from as low as 3200 m (10,500') up to the limit of vegetation at regarding 5400 m (18,000').  It stays in high areas with permanent snow throughout the hotter months of August and Gregorian calendar month, and spends the remainder of the year at lower elevations. The wild yak grazes on grasses, herbs and lichens. commonly it gathers in teams of ten - thirty or a lot of, however it's going to often be ascertained in giant teams of a hundred - two hundred.

The wild yak was once varied and widespread on the complete Tibetan tableland north of the the Himalaya. presently it's found in remote areas of the Tibetan tableland and adjacent highlands, as well as Gansu province, China, with a number of having been ascertained within the Yangtze Kiang Chenmo depression of Ladakh (eastern geographical area, India). Wild yak distribution is very clumped, with most animals in wide scattered herds, focused within the areas with very little disturbance by humans. A survey conducted in 2003 found increasing populations of  wild yak compared to previous surveys taken ten years earlier.

Uncontrolled searching by natives and military personnel is that the main reason for the wild yak's decline. Its vary has been reduced by over [*fr1] throughout this century. cookery remains the most current threat. The wild yak has lost most of the most effective alpine grassland and field surround to pastoralists. issues also are caused by surround disturbance, hybridisation and competition with domestic yaks, and malady transmitted by domestic yaks.
Tidbits

*** The yak was most likely domesticated in Asian country throughout the primary millennium B.C., and domesticated animals currently occur throughout the high plateaus and mountains of Central Asia, in association with folks. Yaks found in zoos square measure sometimes of the domesticated selection, that is smaller than the wild yak. There square measure currently over twelve million domestic yaks within the highlands of Central Asia.

*** The wild yak is supremely well tailored to the tough highlands with its thick coat, nice respiratory organ capability, and skill to clamber agilely over rough parcel. Even its blood cells square measure designed for top elevations - {they square measure|they're} regarding [*fr1] the dimensions of these of kine and are a minimum of 3 times a lot of varied, so increasing its blood’s capability to hold atomic number 8. Its thick coat and low range of sweat glands also are economical diversifications for protective heat. (Schaller 1998)

*** In winter the yak survives temperatures as low as - forty deg C (- forty deg F).

*** Wild yak herds travel on snow in file, rigorously stepping on footprints left by the lead yak.
Status and Trends
IUCN Status:

    1960's - 1994: vulnerable
    1996: Vulnerable (Criteria: A1d+2d, C1)
    2000 - 2004: Vulnerable (Criteria: A1cd+2cd, C1) (Population Trend: Decreasing) (IUCN 2004) 

Countries wherever the Wild Yak Is presently Found:

2004: happens in China and Republic of India. is also extinct in Kingdom of Nepal. (IUCN 2004)
Population Estimates:

    [Note: Figures given square measure for wild populations solely.]

    WORLD
        1995: A preliminary estimate of around fifteen,000 (Schaller 1998)
        2003: seemingly to be but ten,000 mature people (IUCN 2004)

History of Distribution:

The wild yak was once varied and widespread on the complete Tibetan tableland north of the the Himalaya, in central China, Republic of India (Ladakh), Kingdom of Bhutan and Kingdom of Nepal. By around 1970 it had been thought to occur solely in remote areas, primarily within the northern and particularly the northeastern components of Asian country higher than 4000 m (13,000'), with a number of animals still existing in geographic area. presently it's found in remote areas of the Tibetan tableland and adjacent highlands, as well as Gansu province, China, with a number of having been ascertained within the Yangtze Kiang Chenmo depression of Ladakh (eastern geographical area, India). Wild yak distribution is very clumped, with most animals in wide scattered herds, focused within the areas with very little disturbance by humans. For the foremost half, the wild yak's japanese limit currently lies at the transition zone between alpine grassland within the east and alpine field within the west. From here its vary extends westward through southwestern Qinghai Province, China. The western limit of the wild yak's distribution lies between the range and Kuenlun Mountains Ranges in a neighborhood referred to as the Aksai Chin. (Oakland menagerie, Schaller 1998) 

A recent survey conducted on the Tibetan tableland by yankee and Chinese scientists found increasing populations of  wild yak compared to previous surveys taken ten years earlier. Tibet's biology Department has apparently created life protection a priority, with the result that populations of rare animals square measure rebounding. (Schaller 2003)

Distribution Map (4 K GIF) (Huffman 2004)
Threats and Reasons for Decline:

Uncontrolled searching is that the main reason for the wild yak's decline, and it's still the foremost serious current threat. Its vary has been reduced by over [*fr1] throughout this century. additionally, the wild yak has lost most of the most effective alpine grassland and field surround to pastoralists. issues also are caused by hybridisation and competition with domestic yaks, likewise as by malady transmitted by domestic yaks.
Data on Biology and Ecology
Size and Weight:

    The male wild yak will weigh up to one thousand metric weight unit (2200 lb); females square measure 1/3 that size.  Its shoulder height will reach over a pair of m (6.5').

Habitat:

    The wild yak happens (or has occurred) in unforested uplands, as well as plains, hills, and mountains, from as low as 3200 m (10,500') up to the limit of vegetation at regarding 5400 m (18,000'). It reached its greatest abundance on alpine meadows. On alpine field, herds were additionally giant every now and then however were a lot of wide spread, and in desert field they were scarce. (Schaller 1998)

    The wild yak is one in every of the species that board each the Mountains of Southwest China diversity Hotspot (Cons. Intl. two hundred5) and also the Tibetan tableland field world 200 Ecoregion. (Olson & Dinerstein 1998, Olson & Dinerstein 1999)

Age to Maturity:

    In domestic yaks, females initial conceive at the age of three - four years. Full size is reached at six - eight years.

Gestation Period:

 just about 260 days (Bhatnagar 2002).

Birth Season:

    Most births would be expected to occur from Apr through June (Schaller 1998). union happens in Gregorian calendar month (Bhatnagar 2002).

Birth Rate:

    Domestic yaks provide birth to single calves in alternate years, however in areas of poor grazing, a number of might provide birth just once each 3 years, in step with native informants. Wild yaks most likely have an analogous parturition interval. (Schaller 1998) 

Early Development:

 ablactation takes place regarding one year when birth (Bhatnagar 2002).

Dispersal:

    Young become freelance when regarding one year.

Maximum Age:

 twenty three years (Bhatnagar 2002).

Diet:

    The wild yak grazes on grasses, herbs, mosses, and lichens, and crunches ice or snow as a supply of water (Burnie & Wilson 2001).

Behavior:

    The wild yak feeds principally within the morning and evening. attributable to the poorness of vegetation in its setting, the yak should travel long distances to get its required nourishment. it's a sure-footed climber. The wild yak is very sensitive to heat and coordinates its seasonal movements with the temperature and food offer. whereas within the highlands, the wild yak withstands violent winds and snowstorms for hours at a time. It will tolerate temperatures of -40° C (-40° F [Ed. note: Yes, the Fahrenheit and Centigrade temperature scales square measure an equivalent at -40°!]). It additionally bathes in lakes and streams in severe cold. The wild yak stays in high areas with permanent snow throughout the comparatively heat months of August and Gregorian calendar month and spends the remainder of the year at lower elevations.

    The wild yak is usually cautious - if a herd is disturbed, the yaks can hightail it for an extended distance, pace with their tails command erect (Bhatnagar 2002).

Social Organization:

    Most wild yak cows square measure in giant herds with their young with up to a hundred or a lot of animals of all ages and typically each sexes. Herds don't seem to be stable units: they without delay split, or 2 or a lot of might be part of. within the Aru Basin, mean herd size (n = sixty four herds, excluding solitary individuals) is twenty four.5 and also the median is five8.1; elsewhere within the Yangtze Kiang Tang reserve, mean herd size (n = 109 herds) is eleven.3 and also the median is twenty six.5. (Schaller 1998)

    The wild yak is very gregarious. Females and young congregate in giant herds, that erstwhile were reportable typically to contain thousands of people, whereas adult males pay most of the year alone or in teams of as several as twelve. (Tan 1996) 

Density and Range:

 regarding 12-tone system of the Yangtze Kiang Tang reserve in Asian country, China consists of areas of moderate-to-high wild yak density of regarding thirteen sq km/yak (5.0 sq mi/yak). Low-density areas within the reserve might average regarding thirty sq km/yak (12 sq mi/yak) with associate degree calculable a hundred sq km/yak (39 sq mi/yak) in terribly denseness areas. supported rough calculations, the reserve had a density of regarding forty two sq km/yak (16 sq mi/yak). (Schaller 1998)




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