The Guanaco is a wild ungulate found from sea level to over 5,000 meters elevation (González et al. 2006, González in prep.). At the continental and country levels, climate has mainly driven distributional range of the species (González et al. 2013). Guanaco habitat is characterized by highly seasonal climates, dry winters or snow covered, cold temperatures including below zero, winds from moderate to high intensity and low precipitation combined with high evapotranspiration create arid conditions that in general result in low plant productivity (Franklin, 1982, 1983; Wheeler 1995). In the sub-region of Patagonia (Hershkovitz 1972) Guanacos inhabit four of the ten major environments described for South America (González et al. 2006): 1) Desert and Xeric Shrublands, 2) Montane Grasslands, 3) Grasslands, Savannas and Shrublands, and 4) Temperate Forests (Dinerstein et al. 1995). Phytogeographically, Guanacos inhabit the provinces of the Monte and Patagonia, arid and semi-arid shrublands, and grasslands comprising around 1,000,000 km² (Wildlife Conservation Society 2012). On a smaller scale, the presence or absence of this species can be explained by altitude, vegetation, topography, and the occurrence of livestock (Travaini et al. 2007, Acebes et al. 2010, Iranzo et al. 2013, González et al. 2013).

Both migratory and sedentary populations exist across the Guanaco range. Migration is mainly driven by winter forage supply and snow depth as observed for Andean and some Patagonian population before and after the reproductive season (Ortega and Franklin 1995). A minimal annual home range reported for the species is 2-9 km² in sedentary animals (Marino and Baldi 2008), whereas in migratory populations they can reach up to 900 km² in the Andes (González et al. 2008) and around 40 km² in Tierra del Fuego during winter (Moraga et al. 2015).

The Guanaco’s primary natural predator is the Puma (Puma concolor; Franklin et al. 1999) and secondarily the Andean Fox (Lycalopex culpaeus; Novaro et al. 2009).  Its distribution overlaps marginally with other native ungulates such as Huemul (Hippocamelus bisulcus) in Patagonia, Taruka (Hippocamelus anticensis) in mountains of the central Andes, and the Vicuña (Vicugna vicugna) in some parts of the altiplano (Luccherini 1996, Díaz and Smith-Flueck 2000, Rundel and Palma 2000).

Adult Guanacos weigh 80-120 kg (Wheeler 1995, González et al. 2006) and their breeding system is based upon resource defence polygyny, i.e. an adult male defends a territory where birthing and mating occur and a group of females and their offspring (chulengos) feed freely from the intrusion of other males (Franklin 1982, 1983). The Family Group is the basic social unit that occupies a Feeding Territory defended by the resident adult male. Other units found during the reproductive season, include Solo Males that defends a territory without females, and non-territorial Male Groups composed of males of various ages (Franklin 2011). In migratory populations outside the reproductive season, large Mixed Groups can be observed composed of both sexes of all ages (Ortega and Franklin 1995).

Vigilance and foraging accounted for almost 90% of the diurnal time budget for male and female Guanacos in Family Groups, where animals benefited from living in groups as individual foraging time increased with group size, as well as, collective vigilance against predators (Marino and Baldi 2008). Territoriality apparently limits population density, reaching lower K (equilibrium density) when contrasted with models based on individual forage intake (Marino et al. 2015). Empirical field data has also shown that Family Group size is positively correlated with forage production within Feeding Territories (Franklin et al. in press). 

Guanacos are generalist herbivores of intermediate selectivity, i.e. their diets include large proportions of both grasses and shrubs (Raedeke and Simmoneti 1988; Fraser 1998; Puig et al. 1997, 2011, 2014; Baldi et al. 2004). Domestic sheep was the main ungulate introduced across the Guanaco’s range, reaching 22 million within 50 years after its introduction in the Argentine Patagonia in the late 1800s. Guanacos and sheep largely overlap in their forage preferences as much as 80% in some areas (Puig et al. 2001). Although both species can include some 100 plant species in their diets, only 17 species make up 80% of the diets, and in Patagonia two grass species represent 40% for both Guanaco and sheep diets (Baldi et al. 2004). Other introduced ungulates found in Guanaco habitat are goats, cattle, donkeys, and horses, but few studies have assessed their diet overlap with the Guanaco. A preliminary study in the Bolivian Chaco showed that the Guanaco is a generalist feeder, responding to the seasonal availability of fruits, flowers and leaves, including a variety of cacti (Cuéllar, unpublished data). In that same region Guanacos mainly compete for forage and spatial resources with cattle and horses.

Competition with livestock, hunting, and habitat modification has often resulted in Guanacos occupying marginal, low quality lands in terms of vegetation cover and the availability of preferred plant species caused by sheep monopolizing the most productive areas (Baldi et al. 2001, Iranzo et al. 2013). A spatial segregation has been found in northern Chile between Guanacos and Donkeys Equus asinus (Malo et al. 2016).

The Guanaco is a widespread species with an extensive, although discontinuous, range from the northern Peru (8°30’ S) to Navarino Island (55°S) in southern Chile, from the Pacific Ocean in the northwest to the Atlantic Ocean in the southeast, and from the sea level to 5,000 meters elevation in the Andean Mountains (Franklin 1982, González et al. 2006, González in prep.).

However, its distribution has been severely impacted by human beings. Constant hunting, human occupation and fragmentation of habitat, competition with livestock, and the installation of fences (Torres 1992, Franklin et al. 1997, González et al. 2006) have reduced the Guanaco’s distribution to only 26% of its original distribution (calculated by Ceballos and Ehrlich 2002, based upon Franklin 1982). Clearly numerous local populations have become extirpated generating a distribution highly fragmented in many regions (Housse 1930, MacDonagh 1949, Mann et al. 1953, Cunazza et al. 1995, Torres 1992, González et al. 2006, Baigún et al. 2007).

In Peru the northernmost population of Guanacos in South America occurs at 8°30'S (Franklin 1975, Linares et al. 2010) in the Calipuy National Reserve in the La Libertad Department. To the south, populations reach the Salinas Aguada Blanca National Reserve in the departments of Arequipa and Moquegua (16°10'S), and a Guanaco population has been recorded in the Nevado Salcantay area in the Anta District (Wheeler 2006, Veliz and Hoces 2007).

In Bolivia, a relict population of Guanaco persists in the Chaco region (Cuéllar and Fuentes 2000) and recent sightings have been reported in the southern highlands between Potosi and Chuquisaca (Nuñez 2008). Although Pinaya (1990) reported the presence of Guanacos in southeastern Tarija, these records are in need of confirmation.

In Paraguay, a small relict population has been reported in the northwestern Chaco (Villalba 2004).

In Chile Guanacos occur from near Putre village at the northern border with Peru to Navarino Island in the far southern Fueguian zone (González et al. 2013). The largest Guanaco populations in Chile are concentrated in the Magallanes and Aysén regions in the far south.  In the remainder of the country, small and fragmented Guanaco populations occur in the Andean foothills of the extreme north, scattered small pockets along the coast, the north-central zone in the lower Andes, and central Chile exclusively in the Andes (González 2010a, González et al. 2013).

In Argentina most of the world’s remaining Guanacos are found. Although its range covers nearly all of the Argentine Patagonia, Guanaco populations appear to be more scattered towards the northern provinces of the country (Chubut, Río Negro, Neuquén, and Mendoza) compared to the southern region (Santa Cruz and Tierra del Fuego; Baigun et al. 2007, Wildlife Conservation Society 2012). Throughout northern Patagonia, distribution is highly fragmented in relict populations in the La Pampa and southwestern Buenos Aires Provinces. In central and northern Argentina, Guanaco distribution is restricted to the western half of the country along the pre-Andean and Andean mountains up to the border with Bolivia (Baigún et al. 2007). Recently a relict population has been reported in the arid Chaco of northwestern Córdoba (Schneider et al. unpublished data) and in Córdoba Guanacos have been reintroduced (Barri and Cufré 2014).

The Guanaco occurs in a number of protected areas and is included in Appendix II of CITES, thus regulating its international commerce of meat and fine-fiber products to insure that such trade does not threaten the Guanaco’s survival.  In selected areas the sale of Guanaco products in local and international markets has contributed to its “species value” in recovered populations that can be used for reducing human-Guanaco conflict with ranchers and forestry production.  Precaution needs to keep in mind for numerically depressed populations where consumptive and commerce use could irreversibly affect population stability; because of such potential problems, national legislation and international control via CITIES and other programs are relevant and important.

• Peru. Recent legislation ratifies the alarming status of the Guanaco in Peru classifying it as Critically Endangered (Ministerio de Agricultura y Riego 2014). Governmental management of populations has been changed from CONACS (Consejo Nacional de Camélidos Sudamericanos = National Council for South American Camelids) to SERFOR (Servicio Forestal = Forestry Service) and local communities.
• Bolivia. The government is working with local NGOs and authorities to strengthen the management of protected areas for the species. The government has issued an official notice to law enforcement offices in relevant regions concerning the protection of the Guanaco. The main conservation aim has been achieved thanks to the permanent presence of trained indigenous parabiologists and park rangers in the remaining range of the species (Cuéllar unpub. data). The situation is similar in Paraguay were the population is very small and the local NGOs and governmental institutions are working to maintain and protect the last remaining populations of Guanacos in the country.
• Chile. The species is protected by the National Hunting Law (Ley de Caza) that regulates hunting, breeding, and in situ use. However, personnel for law enforcement are insufficient. Only 4% of the country’s Guanaco habitat has effective protection (8,354 km² in 8 National Parks and 4 Reserves). Additionally, there are fiscal and private areas where hunting is prohibited, either with relict populations (7,750 km²) or that directly protect the species (1,212 km²). A National Management Plan does not exist, but regionally a Conservation Plan has been developed for northern and central Chile (Grimberg 2010). Finally, Guanacos have been classified as Vulnerable in northern and central Chile and Least Concern in southernmost Chile by the Environmental Ministry (Ministerio del Medio Ambiente 2012), where the Guanaco is included in environmental assessment of investment projects such as mining, energy, infrastructure, and others.
• Argentina. A National Management Plan (Plan Nacional de Manejo del Guanaco, Baldi et al. 2006) was prepared in 2006 and endorsed by the provinces with the highest Guanaco densities. The plan was coordinated by the Federal Wildlife Agency (Dirección de Fauna Silvestre) involving local institutions with its main focus on the Patagonia. The Federal Wildlife Conservation Law (Ley Nacional de Conservación de la Fauna) and various provincial acts provide a legal basis for the protection and use of the species. In Patagonia, Guanaco conservation measures include sustainable use of the species in the wild, regulation of hunting, and closing of some access routes and oil trails. Nevertheless, law enforcement capacity is low since most provinces lack sufficient personnel and equipment to control vast areas. Protected areas in the Patagonian steppe would encompass 10% of the Guanaco population if effective, but most protected areas are rather nominal as they contain livestock, lack wildlife guards, and poaching is common. The percentage of the area under effective protection in the Patagonian steppe is estimated at a disconcerting level of less than 1% (Walker et al. 2004). In the central provinces there are eleven protected areas (national, provincial and private). In general, progress has been made in legislation and management tools, but implementation is needed.