Described as an elegant animal, with a long, slender neck and fine legs by Charles Darwin, the Guanaco is the biggest wild camelid family member in South America, and thought to be the domestic llama's ancestor. A guanacos's eyes are on the sides of its head, allowing it to look all around it for threats. Its ears are erect and straight, giving them a curious and attentive look. Like other camelids, guanacos walk on enlarged sole pads, only the tips of its hooves touching the ground. These pads are moveable, helping to provide a grip on gravelly and rocky terrain.
Guanacos are native to the Andean mountains of South America. They can live at elevations from sea-level to over 4,500 meters. They are found in high-mountain regions of Peru, Bolivia and Chile as well as in Patagonian and Tierra del Fuego grassland in Argentina and Chile. In addition, there is a small introduced population of Guanacos on the Falkland Islands. They prefer semiarid and arid habitats, including desert grassland, shrubland, savanna, and sometimes forest. Some populations are sedentary, while others make seasonal migrations, sometimes moving to lower altitudes in order to avoid drought or snow cover.
Guanacos have a reasonably flexible social system, with populations being either migratory or sedentary, depending on the availability of forage. During the mating season, they are found in three main social units: family groups, groups of males, and associations of males that are solitary. A territorial adult male heads each family group and contains a varying number of young and adult females. Aside from family groups, the non-breeding, non-territorial adult and juvenile males form groups between 3 and 60 males, and forage in separate male-group zones. The mature males that have territories but do not have females are known as solitary males, and may form associations numbering about 3. Guanacos make a range of vocalizations to convey information and negotiate social roles. Notable among them are alarm calls, used to warn other members of the group about potential predators, and clicking sounds, used in combat between males.
Guanacos are polygynous animals and only the dominant male of any herd is able to mate with the females. This is why there are such fierce battles among males to lead a group of adult females. Mating occurs from November to February. Gestation lasts for 11.5 months, a single offspring being born to each mating female every year. The young, known as chulengos are precocial, able to stand as soon as 5 to 76 minutes after being born. Chulengos have a behavior of following the mother, rather than hiding; as a way of avoiding predation in open habitats. Due to the need to grow quickly, the chulengos begin to graze when just a few weeks old, foraging almost exclusively by 8 months old when weaning occurs. They remain with their group until they are about 11 to 15 months old, at which time the adult male usually forces them out. Female guanacos achieve sexual maturity the age of 2 years old and mate from the age of 3. Males are sexually mature from 2 to 4 years of age.
Major threats to guanacos include overhunting, for meat, skins and wool, and also poaching, habitat degradation, isolation and fragmentation of populations as a result of development and erecting barbed wire fences. Drought and overgrazing, possibly due to climate change, are further threats to this animal's habitat. Sheep breeders will often kill guanacos, viewing them as competitors with sheep as well as possible transmitters of disease, although it could be that diseases from domestic livestock are more likely to threaten guanacos.
According to the IUCN Red List, the total estimate for the guanaco population is around 535,750–589,750 animals, including estimates for specific regions: Argentina: 466,000–520,000 individuals; Bolivia: 150-200 individuals; Chile: 66,000 individuals; Paraguay: 100 individuals; Peru: 3500 individuals. Overall this species' numbers are stable currently and it is classified as least concern (LC) on the list of threatened species.
Throughout its distribution, a guanaco plays an important role maintaining ecosystem function. It disperses seeds in its feces, controls the growth of vegetation by browsing and grazing, and is a food source for its natural predators.