structural:expansion
Ecology

The guanaco is a diurnal animal. It lives in small herds consisting of one male and several females with their young. When the male detects danger, he warns the group by bleating. The guanaco can run up to 64 km/h (40 mph; 18 m/s). This speed is important for the survival of guanacos because they cannot easily hide in the open grasslands of the Altiplano.

Natural predators of the guanaco include pumas and the culpeo or Andean fox. Fox predation was unknown until 2007 when predators began to be observed in the Karukinka Reserve in Tierra del Fuego. Scientists attribute this the unfavourable climatic conditions on the island, which are causing food to become scarce, weakening the animals. The absence of pumas on Tierra del Fuego is also believed to be a factor that allows the fox to occupy their ecological niche. Finally, it is believed that this behaviour is not new, as the fox is nocturnal, which makes any predation challenging to observe. Faced with the threat of the fox, guanacos resort to cooperative strategies to protect their young with a shield formation, a circle around the vulnerable. If they are successful, they chase the fox away, which would be impossible with a puma.

When threatened, the guanaco alerts the rest of the herd with a high-pitched bleating sound, which sounds similar to a short, sharp laugh. The male usually runs behind the herd to defend them. Though typically mild-mannered, guanacos often spit when threatened, and can do so up to a distance of six feet.