Distribution: The Guanaco is the wild South American ungulate with the broadest geographical distribution. The Guanaco is found in northwestern Peru (8°S), in the western and southern Bolivia, northwestern Paraguay, and throughout the Andes of Chile and Argentina eastward to the Atlantic coast and southward to the islands of Tierra del Fuego and Navarino (55 °S). The guanaco occupies a wide range of arid and semiarid ecosystems from sea level to over 4,500 meters in elevation. It is estimated that over 90% of guanacos in Argentina are found in the Patagonia.
Subspecies: Recent studies, based on mitochondrial DNA analysis, recognize two subspecies: Lama guanicoe cacsilensis, in the north between 8 and 20 ° S, and Lama guanicoe guanicoe in the south from 22 to 55 ° S. While the former subspecies includes small, isolated populations no larger than 3,000 individuals, the second subspecies is distributed more continuously towards the south, totaling about 600,000 individuals.
Population: The pre-Hispanic population of guanacos is estimated at 30 to 50 million individuals. Since European settlement and the introduction of domestic herbivores, the total population has declined drastically. At present, the total population is around 600,000 individuals (10% or less of the population existing 100 years ago) and has lost 60% of its original range.
In the southern portion of its range, guanacos are more abundant and with a more continuous spatial distribution, populations of relatively high densities are rare, spatially restricted, and separated by hundreds of kilometers in which densities are very low (less than 2 guanacos per km2) or zero.
In the case of Peru, Bolivia and Paraguay, the species is severely threatened. At present, there are guanaco population estimates by country, however due to disparate sampling schemes, there is an urgent need to undertake censuses with comparable methodologies.
According to the latest assessment by GECS for the Red List (2008), guanacos were categorized as a species of “Least Concern” http://www.iucnredlist.org/details/11186/0. Given the heterogeneity of the conservation status of guanaco populations among countries, GECS is working on a re-categorization at the sub-population level because we realize that the category “Least Concern” does not reflect the status of many of the guanaco populations that are currently threatened.
General Ecology: The guanaco’s social system is seasonally based upon resource defense polygyny in which females are attracted to a favorable forage site defended by a territorial male. The primary social units are Family Groups, Male Groups, and Solo Territorial Males. Populations are either sedentary or migratory. While the territorial male may reject females attempting to enter his Family Group and territory, he does not control the movements of females if they leave; this it is distinct from a classical ‘harem’ reproductive system. Females give birth annually in the spring and again mate approximately two weeks later.
The guanaco is a generalist herbivore of intermediate selectivity. This implies that it is able to consume most of the available plant species, and in significant proportions both grasses and herbs as woody species, mainly shrubs. The domestic sheep is also a generalist of intermediate selectivity in terms of their foraging strategy. Studies carried out in Patagonia have shown that guanacos and sheep significantly overlap in their dietary preferences, and although they are able to consume about 100 plant species, 80% of their diet consists of only 17 species of plants available in the environment.
The first estimates of the area of activity of breeding groups obtained by radio telemetry in eastern Patagonia reveal that these groups occupy bounded territories, between 2 and 9 km2, that are stable in time and space. On the other hand, data from a population in Mendoza, Argentina, demonstrates areas of activity greater than 80 kilometers. In mountain environments of north-central Chile, guanacos demonstrate altitudinal migration between 1,000 and 4,400 m, which is a change in the area of activity between 65 and 163 km2.
Group size influences the size of the activity area, as well as time invested in feeding and vigilance for predators. Therefore, it is important to consider that in highly social animals like the guanaco, the processes of inverse density dependence in small populations, known as the Allee effect, increase the potential probability of extinction at low densities. In particular, for animals that tend to cluster, populations may decline rapidly if a minimum group size is needed for successful reproduction or to avoid predators. However, recent studies on Effective Population Size revealed for a mainland population to be 34-43 individuals and an island population as low as 10-15 that still maintained high genetic diversity. Predation by pumas has been described for populations of high density guanacos in Chile and Argentina. Recently, the puma has re-colonized much of its former range, and its effect on guanaco populations can be significant and tend to increase in the near future.
Management systems: The species is classified under Appendix II of CITES in all countries of its range. While in the case of Argentina, the National Management Plan mandates that the fiber can only be exported if obtained from live- shorn animals, in Chile culling and exportation of hides and meat are authorized.
In Peru, more intensively than in Argentina, capture, shearing and release of wild guanacos has increased during the last five years. The initiatives of shearing wild guanacos began in the late 1990s in the Argentine Patagonia, and have grown rapidly, particularly in the province of Rio Negro where more than 11,000 guanacos have been captured, shorn, and released since 2003 at seven sites, which has produced more than 4,500 kilos of fiber. There are no known long-term effects that this management system has on wild populations.
In contrast, there are guanaco breeding ranches for fiber production, where animals are under total control by man.
The formation and maintenance of stocks in breeding ranches require the extraction of guanacos (adults or chulengos, a word that refers to the offspring) from wild populations. Considering the two management systems, use of wild guanacos can contribute effectively and directly to the conservation of the species, however, only if the effects of this approach on population processes is investigated.
Threats to the conservation of wild populations:
- Direct Threats
a. Habitat degradation and fragmentation
b. Unplanned hunting and culling
c. Inter-specific interactions with sheep and introduced species
d. Population fragmentation by fencing cattle plots
e. Elimination of guanacos due to presumed competition with f domestic livestock
- Indirect Threats
a. Institutional weakness
b. Lack of effective protected areas
c. Lack of information on the effects of management methods and implementation of management plans
d. Lack of incentives for local participation in management plans