Characteristics
The sheep is particularly known for its long, spiraling horns which have been measured having a span up to 140 cm (55 in). They have the longest horns of all sheep, with the longest individual horn ever recorded measuring 1.9 m (6.2 ft) and weighing 60 lb (27 kg). O. a. polii's horns follow a coil pattern, with the tips pointed directly away horizontally from the head; in spite of this, the tips are rarely broken. The horns have long been a popular attraction for trophy hunters. They begin growing 15–20 days after the sheep are born, and their growth in length is most pronounced during the first year. Thickness growth is most noticeable during the first two years.
Ovis ammon sheep are colored a dark brown, with white underparts: the two different sections are separated by a dark band of hair. There is a white patch on the rump as well, which is not so clearly defined on most subspecies except O. a. polii. As winter approaches, the white hair on males grows longer, until it becomes a prominent ruff, although on O. a. polii the ruff stands out less than other subspecies. Females' coats are lighter than the male's, and do not have such a drastic seasonal change. Marco Polo sheep's face is lighter colored than the body.
Most argali have a round tail approximately 6 to 10 centimetres (2.4 to 3.9 in) long, ending in a tuft of hair; O. a. polii's tail is a little bit longer: around 12 to 16 centimetres (4.7 to 6.3 in).
Mature rams on average weigh 126 kg (280 lb). At the withers, rams grow to approximately 113 cm (44 in) in height and ewes to 100 cm (39 in). The sheep rut in December. Gestation lasts about 160 days, with single births being normal and twins uncommon. A captive ewe once gave birth to five lambs at once, then triplets two years later.
Marco Polo sheep have an average life span of 13 years. The horns develop rings each year by which the age of male animals may be determined. Since females do not have horns, however, it is harder to determine their age.
No data have been compiled showing the susceptibility of the sheep to disease, although tests have been run on similar species of sheep and the data may be similar. Since Marco Polo sheep are reluctant to approach people, it is not likely that they can catch diseases common to domestic flocks, although some domestic sheep are allowed to run wild over the mountains, and it is unknown if they come into contact with Marco Polo sheep. However, the shepherds in the area do not generally have access to veterinary care for their animals, and it is possible that these could transmit diseases to the wild sheep.
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