Lama guanicoe (Statius Muller, 1776)
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https://doi.org/ 10.5281/zenodo.5719719 |
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https://doi.org/10.5281/zenodo.5719723 |
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https://treatment.plazi.org/id/03928E69-9A41-FFC8-D579-FE7AF5F5F837 |
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Conny |
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Lama guanicoe |
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Guanaco
French: Guanaco / German: Guanako / Spanish: Guanaco
Taxonomy. Camelus guanicoe Muller, 1776 ,
Patagonia, Argentina.
The Guanaco is a direct descendent of Hemiauchenia, a genus of camelid that migrated from North to South America three million years ago. Two million yearold fossils of L. guanicoe can be found today in Argentine Pleistocene deposits and others in strata dated 73,000 -97,000 years ago in Bolivia. Phylogenetically, L. guanicoe is monophyletic. Historically, four sub-species of Guanacos were recognized, albeit based upon incomplete information on skull measurements, coat coloration, distribution, and body size. However, recent molecular studies using mtDNA cytochrome-b sequences, recognize only two subspecies, placing the Peruvian and northern Chilean populations in subspecies cacsilensis and assigning the remainder of the clade to subspecies guanicoe . A significant biogeographic revision of the two valid subspecies is needed, especially an analysis and classification of populations on a regional and ecosystem basis.
Subspecies and Distribution.
L. g. cacsilensis Lonnberg, 1913 — N Peru to N Chile between 8° S and 22° S. Introduced from Argentina to Staats I (Falkland Is) during the late 1930s. View Figure
Descriptive notes. Head-body 190-215 cm,tail 23-27 cm, shoulder height 90-130 cm; weight 90-140 kg. Measurements vary because of their wide distribution and differences between subspecies. Guanacos are extremely striking, with their contrasting colors, large, alert brown eyes, streamlined form, and energetic pace. Described by Darwin as “an elegant animal, with a long, slender neck and fine legs,” itis one of South America’s largest terrestrial mammals, reaching its maximum size in southern Chile and smallest in northern Peru. There is no obvious sexual dimorphism in size, color, or structure, except for the presence of large canines in the male. The color of the woolly pelage is similar for all Guanacos, varying from light brown with ocher yellow tones in the north to dark reddish brown in the south. The chest, front of neck, belly, and internal portion of the legs are more or less pure white, the head gray to black. Guanaco wool is prized for its softness and warmth, and second only to that of the Vicuna ( Vicugna vicugna ). The pelts from “chulengos” (newborns and less than one-year-old juveniles) are particularly soft. Like their domestic descendant the Llama ( L. glama ), the Guanaco is double-coated, with coarse guard hair (3-5% offleece) and a soft undercoat. The undercoatfibers range 12-17 (average 14-16) microns in diameter. Fiber (strand) length is 35 mm, the same as the Vicuna. Average fleece weights vary from 322 g to 350 g. Fiber diameter increases about two microns from one to seven year of age. Value of shorn, unclean wool is US $ 100-200/kg and US $ 400/kg for cleaned and dehaired wool. Guanacos have “thermal windows” in the front and rear flanks (underarms) that are nearly without wool. Both wild and captive Guanacos may live as long as 28 years.
Habitat. The Guanaco inhabits environments from sea level up to 4500 m or more, characterized by highly seasonal weather, with snow cover or dry winters, cold to freezing temperatures, moderate to high winds, and low precipitation. These combine to produce high evapo-transpiration and dry conditions that lead to low primary productivity. At a broad scale, Guanacos inhabit four of the ten major habitats found in South America: desert and xeric shrublands, montane and lowland grasslands, savannas and shrublands, and temperate forests, which botanically include the categories of Puna, pre-Puna, Andean steppe, Chacoan grasslands and shrublands, Espinal, and the southern Pampa. They inhabit flatlands, hilly foothills, and mountainous environments. In the arid habitats of southern Chile, isolated mesic subsystems were the preferred plant community accounting for 85% of female sightings and 60% ofterritorial males. These “vegas” (meadows) were not only preferred for their productive, higher-quality succulent forage, but for females a major influence for their selection was the avoidance ofsites and habitats favored by Pumas (Puma concolor).
Food and Feeding. The Guanaco is a non-specialized, opportunistic, intermediate, mixed-feeding herbivore, foraging on a wide variety of plants. It is basically a grazer, but also browses. When the availability of the herbaceous strata decreases or becomes unavailable, especially during winter, Guanacos feed mainly on the shrub or tree strata. This flexibility as a generalist to change diet according to availability or preference extends to eating epiphytes, lichens, fungi, cacti, succulent plants, fruit, flowers, and leaves. Their summer diet in a mixed habitat of southern Chile averaged 62% grasses (mainly Festuca ), 15% browse (Nothofagusspp.), and 11% forbs, which were particularly important in the spring. In another study on Tierra del Fuego their diet was made up of 90% grasses and forbs. In austral coastal forests of southern Chile, Guanaco browsing significantly diminishes the rate of regeneration of the commercially important southern beech tree (Nothofagus pumilio) and was a limiting factor on initial growth of seedlings and saplings (89% were browsed), although the Guanaco’s diet was less than 10% shrubs and trees. At Torres del Paine National Park, at the western edge of the Patagonia, vegas were highly utilized in summer (86% ofall feeding observations) and preferred by all feeding Guanacos (n = 1659) in family groups, whereas all other vegetation types were avoided (shrub = 3%, upland = 10%). Adult females in family groups showed the greatest feeding preference for vegas, followed by chulengos, yearlings, and adult males. In Argentine Patagonia, Guanaco densities are low and negatively related to domestic sheep numbers. Guanacos and sheep largely overlap in their forage preferences, with over 80% oftheir diets being identical. Histological analysis of fecal samples revealed that Guanacos and sheep were intermediate herbivores feeding on a wide range of grasses and forbs, capable of changing their diets seasonally, and their food niches greatly overlapped particularly in summer when food resources were more scarce than in spring.
Breeding. Nearly all females breed at two years of age and have their first offspring as three-year olds. At Torres del Paine, Chile males began breeding after obtaining a feeding territory when they were 2—4 years of age. Essentially all breeding took place within feeding territories during the summer. A high percentage (88%) of males established a territory for three or fewer years (average 2-3), although some males held territories for as long as eight years. Few solo males became family group males (19%), that is, 81% remained non-reproductive during their territorial tenure. Those males leaving male groups to become territorial, only 35% directly became family group territorial males while 65% became solo territorial males. Like other camelids, Guanacos are induced ovulators. The territorial mating period was from early Decemberto early January (91% of 88 observed copulations), so males defended their feeding territories for nine weeks before and eight weeks after the mating season. Mature female Guanacos give birth to a single offspring each year after a gestation of about 11-7 months (345-360 days). Only three sets of twins were documented in over two decades offield studies at Torres del Paine during which several thousand newborns were observed; in all cases no more than one survived past the first week. Half of all births occur in the last two weeks of spring. The timing of parturition varies with latitude. At Torres del Paine the birth season occurred from late November to early January. Parturition occurs during the day in Patagonia with 78% of births between 10:00 h and 14:00 h, when the young are able to dry during favorable midday temperature conditions. Birth weight averages 13 kg (7-15 kg) and shows marked density dependence, with lower birth weights at higher population densities. Low weight at birth is related to high rates of mortality. Newborns are very precocious. They can stand as early as 5-76 minutes after birth and can run within hours. Young are weaned at 6-8 months and are expelled from family groups by the territorial male when they are 11-15 months old. Dispersing yearling males join male groups and yearling females join family groups or female groups. Monitoring of 409 radio-collared chulengos at Torres del Paine over a seven-year period revealed an average first-year survival rate of 38% (31-55%). Puma predation was the primary cause of mortality of young Guanacos, especially in the first two weeks of life. Relative to their availabilities, chulengos were preyed upon about four times as much as adults. With every centimeter increase in winter snowfall, the risk of chulengo mortality increased by almost 6% because of greater vulnerability to predation. Out of 731 Guanaco skulls collected at Torres del Paine from 1979 to 1988, 33% showed clear evidence of having been killed by Pumas, and that was considered an underestimate. Observations of farmed Guanacos revealed that allosuckling (nursing of non-filial offspring) comprised 6% of all suckling events by 62% of calves and was allowed by 52% of dams. Dams whose calves performed allosuckling exhibited poorer body condition, suggesting juvenile Guanacos allosuckled to compensate for nutritional deficiencies. Preliminary research on the cytochrome-b gene sequence has found no evidence of hybridization between Guanacos and Vicunas.
Activity patterns. Observations of both wild and captive Guanacos have shown peaks of eating, bedding, and ruminating in the morning and again later in the afternoon. Wild Guanacos spent a greater proportion of their time moving and less time resting, probably the result of the need to forage more and maintain intraspecific social interactions. At Torres del Paine during the summer, Guanacos in family groups in vega habitat fed 54% of time, rested 45%, and were involved in other behaviors 1% of the time (3084 focal observations). There was no difference in the activity-time budgets of 23 marked solo territorial males compared to family-group territorial males based on social group type, total number of females, total number of Guanacos present, or age of the ter ritorial males. The pattern suggested thatterritorial male behaviors were related to resource defense rather than to any direct ability to attract potential mates. Males, in all categories, spent most of their time foraging (65% of overall time budget). However, based upon habitat type there was a significant difference in time spent in aggressive and in miscellaneous activities (defecation, alertness to observer, scratching). Most aggressive encounters and miscellaneous activity occurred on hilltops of areas dominated by mata barrosa shrubs (Mulinum spinosum). Vigilance patterns were assessed in Chubut, Argentina for Guanacos occupying a tall shrubland covering 40-60% of the area, where 40% of the mortality was from Puma predation. Family group territorial males devoted more time to scanning their surroundings and less time feeding than did females, and both sexes benefited from grouping by reducing the time invested in vigilance and increasing foraging time. Males reduced the time invested in vigilance as the number of females in the group increased, while the presence of chulengos increased territorial male vigilance. However, in closed habitats collective vigilance increased with the number of adults but decreased with the number of chulengos. Although male and female Guanacos differed in their time allocation, results supported the hypothesis that both sexes received significant anti-predator benefits from group living. Adjustments in Guanaco body posture can modify the exposure of body surface area H—22%. Guanacos can decrease and increase body heat loss through radiation and convection by “closing” and “opening” their thermal windows in the axillary and flank regions. Researchers report that when ambient temperatures were 0-10°C, animals used postural adjustments to decrease the area of the thermal windows by 5-7% oftotal surface area. At temperatures greater than 10°C they increased the area of the thermal windows up to 22% to regulate heat loss through radiation and convection. When the temperature was below 0—1°C Guanacos bedded and huddled together, often with their hindquarters into the wind.
Movements, Home range and Social organization. Intensively studied Guanaco populations have been either migratory or sedentary. In the San Guillermo Biosphere Reserve ( Argentina), both occur but most are sedentary, while on the island of Tierra del Fuego ( Chile) both occur, but most are migratory. In Argentina populations have been reported to be migratory over short distances, altitudinal-facultative migratory, and strictly sedentary. On Tierra del Fuego sedentary populations were incompletely so, because during the winter when territories were snow covered, many or all of the family group members abandoned the site, leaving the territorial male by himself or only with a few members. The following spring the male regained his group membership. Although some local populations now appear to be sedentary at Torres del Paine, in the 1970s and 1980s the population was completely migratory. In those decades essentially all animals abandoned the summer range and moved in late autumn 8-18 km to where the snow was less deep and browse species were more abundant. The following spring the animals returned to their summer range. Daily movements of family groups on Tierra del Fuego were highly predictable: days were spent in open meadows feeding and nights were spent resting in the adjacent closed Nothofagus forest. In the open habitat of Torres del Paine, the animals spent days on territories and nights on adjacent slopes or hill tops. The social organization of Guanacos is similar to that of Vicunas, except that territorial, resource-defense polygyny is seasonal instead of yearround and there is fluid movement of females between male territories. The social units of Guanacos for the migratory population at Torres del Paine were family groups, male groups, solo males, mixed groups, and female groups. Typical family groups were composed of one adult territorial male, seven females, and four juveniles less than 15 months old. Group size and composition frequently changed. Family groups occupied feeding territories 7-13 ha in size, which were defended by the resident male. With minor adjustments to the center of activity from year-to-year,territory locations were the same, spatially discrete, and non-overlapping. There was no indication of defended sleeping territories as found with Vicunas. Although family groups were “open” in the sense that females couldjoin and leave at will, the territorial male determined whether or not females were accepted into or rejected from the group. In a study of marked territorial males at Torres del Paine, most (73%, n = 60) returned to the same territorial location from year-to-year. Those males (27%) that shifted territorial locations showed no pattern in changes between solo territorial males and family-group territorial males. Male groups were composed of non-breeding, non-territorial, immature and mature males. Group size was highly variable (3-60) and averaged about 25. Male groups lived apart from family groups, in male-group zones. Solo males were mature males with an established territory, but commonly without females; the mean “group size” for solo males was three. Mixed groups formed in winter and included Guanacos of both sexes and all age classes. They averaged 60 animals with as many as 500. Female groups were gatherings of females of all ages and occasionally included a small number of immature males. These groups came together temporarily immediately before and after the winter migratory season. Female group size was highly variable, and could number 10-90 animals. At high population densities, the size of Guanaco territories can decrease significantly. Large female groups and their chulengos can shift daily from territory to territory. The annual cycle of migratory Guanacos at Torres del Paine was divisible into four general socioecological periods: summer territorial, autumn transitional, winter aggregational, and spring transitional. The summer period was the longest, from mid-October to the end of March. This was reproductive season, during which males defended territories and when birth and mating occurred. The summer territorial social units were 35% family groups, 15% male groups, 42% solo male groups, and 8% female groups. Most of the animals (65%) were in family groups; 21% were in male groups, 7% were solo males, and 3% were in female groups. The autumn-transitional period was short, lasting from early April to late May, and Guanacos were mainly in family groups and male groups. During this period the territorial system broke down as the Guanacos began migrating to their winter range. The winter aggregational period extended from early June through late August. In this period, the social units were primarily mixed groups (39%) and female groups (41%) with most of the animals (80%) in mixed groups. The spring-transitional period started in late August and ended in mid-October. At this time all social units were found with equal proportion of Guanacos in family groups and male groups. Differences in the weather from year-to-year, especially at the beginning and end of winter, caused slight variations in the timing of animal movements, formation of social groups, and migration. Snow storms and snow cover were especially important in triggering sudden movements west to the winter grounds.
Status and Conservation. CITES Appendix II. Classified as Least Concern on The [UCN Red List. Northern subspecies cacsilensis is recognized as Endangered on The 2006 IUCN Red List with about 4000 remaining.The Guanaco is the most widely distributed native artiodactyl in South America. It originally ranged from the Andean areas of northern Peru, south to Bolivia and adjacent parts of Paraguay and down to Tierra del Fuego, covering most of Argentina and Chile. Based upon the carrying capacity of the territory Guanacos originally occupied, the pre-Hispanic Guanaco population in southern South America has been estimated to be 30-50 million. Indiscriminate hunting and competition with sheep, particularly during the past century, caused a steep decline in numbers. In the Argentine Patagonia the introduced sheep reached 22 million head within 50 years in the late 1800s and early 1900s. Today, the best estimate of the total Guanaco population is 536,000-840,000 animals. Although still widely distributed, the Guanaco’s current distribution is less than 40% of its original range, with remaining populations often isolated and fragmented. The killing of young chulengos for their soft skins has had a serious impact on Guanaco populations, especially in Patagonia. Some 444,000 skins were exported from Argentina between 1972 and 1979. The number dropped to 10,000 annually by 1984, reflecting decreased availability. Conservation classification and laws regarding the remaining Guanaco populations vary from nation to nation, based primarily upon total numbers and without regard to subspecies. Percentage of total remaining numbers and conservation classification by countriesis as follows: Argentina 87% (considered not endangered or potentially vulnerable), Chile 12% (vulnerable and protected), Bolivia 0-03% (endangered and protection in development), Paraguay 0-02% (endangered and not protected), and Peru 0-62% (endangered and active management being pursued). Thus at the national level, relict Guanaco populations are faced with potential extinction in three out of the five countries where they were found historically. In Argentina management plans are beginning to include utilization of the Guanaco for meat and wool. Today, around 35% of the high density populations identified in Argentina are under programs that call for live-shearing Guanacos for sustained use of their valuable wool. Also in Argentina, the country with the most Guanacos, a National Management Plan has been prepared and endorsed by the provinces with the highest Guanaco densities. However, less than 1% of the area in the Patagonian steppe is estimated to be under effective protection. Guanacosstill have a wide distribution, an apparently stable population trend, and large populations in protected areas. However, it is not uncommon that protected areas are in name only because they contain competing livestock, there are no wardens or guards, and poaching is common. Conservation priorities for the Guanaco include all of the following: improved and accurate population surveys; adequate habitat protection; regulation of hunting quotas; where feasible, live-shearing; protection of remnant populations from poaching (especially in Peru and northern Chile); more explicit goals and policies (for example in southern Argentina and Chile); confronting Patagonian land use practices, which focus on maximizing sheep numbers; addressing the need for unified laws and management schemes between countries; and finally and especially, the implementation of conservation oriented management at local, national, and international levels.
Bibliography. Baldi, Lichtenstein et al. (2008), Baldi, Pelliza-Sbriller et al. (2004), Bank et al. (1999, 2002), Cavieres & Fajardo (2005), Franklin (1974, 1975, 1982, 1983, 2005), Franklin & Grigione (2005), Franklin, Bas et al. (1997), Franklin, Jonson et al. (1999), Franklin, Poncet & Poncet (2005), Garay et al. (1995), Gonzalez et al. (2006), de Lamo et al. (1998), Marin, Casey et al. (2007), Marin, Spotorno et al. (2008), Marin, Zapata et al. (2007), Marino & Baldi (2008), Montes et al. (2006), Nugent et al. (2006), Ortega & Franklin (1988, 1995), Puig et al. (1995, 1996, 1997, 2001), Raedeke et al. (1979, 1988), Riveros et al. (2009), Sarno et al. (1999a, 1999b, 1999¢, 2001, 2003), Sosa etal. (2005), Stanley et al. (1994), Wheeler (1995a, 2006a, 2006b), Young & Franklin (2004a, 2004b), Zapata et al. (2010).
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