By Anna Bess Sorin
Geographic Range
Found from southern Peru down the Andean zone of Chile and Argentina to Tierra del Fuego and Navarino Island. There is also a population in far western Paraguay.
Biogeographic Regions:
neotropical 
(native ).
Habitat
Guanacos inhabit grasslands and shrublands from sea level to 4,000m. Occasionally they winter in forests.
Terrestrial Biomes:
desert or dune ; savanna or grassland ; mountains .
Physical Description
(253 to 308 lbs)
They stand at 1,100 to 1,200mm at the shoulder and have slender bodies with long limbs and neck. The head is typical of camelids with long, pointed ears and cleft, highly mobile lips. Their fur can be long, thick and wooly, especially along the flanks, chest and thighs. It is reddish-brown dorsally, and the underparts are white.
Some key physical features:
endothermic ; bilateral symmetry .
Reproduction
Females are apparently induced ovulators, and especially in the southern end of the range breeding reaches a peak in February. Young are born in December to February after an eleven month gestation period. They weigh 8-15kg at birth and nurse for eleven to fifteen months. Females may begin to breed as early as one year of age, sometimes younger, though two to three years old is more typical.
Key reproductive features:
gonochoric/gonochoristic/dioecious (sexes separate); sexual .
Behavior
There are three types of social groups: family groups, male troops, and solitary males. A family band is composed of a single breeding male, several females, and offspring. Males limit the size of their group by driving out young males of six to twelve months and driving off males and sometimes females trying to enter the group. Males defend a territory that the group resides on, and the territory is demarcated by large communal defecation piles. Only about 18% of males are in a family group; the others are in bands or solitary. The all-male bands are generally made up of young males. Males in these herds learn fighting ability through play fights. The solitary males tend to be mature males looking for females or herds to take over.
Key behaviors:
motile .
Food Habits
Guanacos are herbivores that can inhabit dry areas and forego drinking for long periods. They are versatile foragers, both browsing and grazing on grasses and plants.
Economic Importance for Humans: Positive
Guanacos have long been hunted for their meat and fur. They are believed to be the ancestor to the now domesticated llamas and alpacas, which are important as beasts of burden and for their fur.
Conservation Status
Guanacos have had their numbers drastically reduced due to human pressures of habitat encroachment, habitat destruction, and hunting. In addition, climatic changes are also blamed for decreases in population size and range.
Other Comments
Guanacos when young are vulnerable to pumas, but the reduction in the puma populations has lead to mortality due to starvation.
Adult guanacos can run at speeds of up to 56km/hr.
Contributors
Anna Bess Sorin (author), University of Michigan.
