A principally diurnal species, vicuñas have a unique system of territoriality. A day-time territory is used for grazing, and is connected to a higher sleeping territory by an undefended corridor. Together, the two territories cover 7-30 hectares, marked by dung heaps. Families are close-knit, with the dominant male keeping individuals within 50 meters / 160 feet of each other at all times. In addition, these family groups are closed - with immigration virtually eliminated by the dominant male. Juveniles of both sexes are evicted from the group by the reigning male - young males at 4-9 months, and females at 10-11 months of age. Communal latrines are used by each family group. Very shy and constantly alert, vicuñas will flee at the slightest sign of danger. They can run at nearly 50 kmph / 30 mph at elevations of 4,500 meters / 15,000 feet, aided by a heart which is almost 50% larger than the average weight for similar sized mammals. The warning call is a high soprano whistle. Vicuñas must drink daily - an important factor used when determining a family's range.
The overall colour of the soft wooly coat is ochre, light cinnamon, or reddish brown, with the underparts, insides of the legs, and underside of the head being dirty white. On the chest, at the base of the neck, is a peculiar, pompon-like 'mane' of silky white hairs which may be 20-30 cm / 8-12 inches in length. The vicuña is extremely slender, with long skinny limbs and neck. The head is small and wedge shaped, with small, triangular ears. Unique among living artiodactyls, the incisors of the vicuña are constantly growing, with enamel on only one side, to keep up with the wear caused by the tough grasses on which they feed.
