C. Michael Hogan PhD
December 7, 2008
L. guanacoe is an athletic camelid, who was prehistorically a dominant herbivore on the South American continent. This gregarious herd animal grazes on the expansive plains and high plateaus of much of western and Patagonian South America. The Guanaco is a pseudo-ruminant, whose habitat has been greatly restricted by encroachment of ranching and grazing activities over the last several centuries.
The species is distributed widely over the arid grasslands of much of the Andean spine of South America including the expansive Patagonian steppes of Chile and Argentina and the near coastal altiplano of Peru, Bolivia, Ecuador and Colombia. Guanaco occur from sea level to an altitude of up to 3500 meters. The southern limit of the range includes Isla Navarino in Tierra del Fuego.
L. guanacoe attains a shoulder height of 1.05 to 1.25 meters, with body mass of approximately 88 kilograms. Fur appearance may be light brown to dark cinnamon, with a clearly demarcated white belly and chest. Muzzles of these camelids are grayish and the straight diminutive ears appear alert. Tail length is approximately 25 cm. L guanaco does not have hoofs, but rather two toes underclad with a cutaneous pad, which is capable of muscular movement to grip the steep hillsides of its grazing range. The large brown eyes are prominent, since Guanacos often stand and gaze at the human exploring their private realms of the remote Andean plateaus. L guanacoe incisors have well developed roots, a characteristic distinguishing the species from the vicuna. These spatulate incisors also have enamel on both the labial and lingual surfaces. The upper lip is split into two symmetrical lobes, with each side capable of independent muscular control. Guanacos produce distinctive vocalisations for herd alarm and other communication; these sounds are particularly pronounced when a herd is encountered in a quiet area far from any normal vestige of civilisation..
The Guanaco is a pseudo-ruminant, with a tripartite stomach organ. The first compartment of this lamoid's stomach presents two marked areas of sacculation, the smaller at the lowest point of the cranial sac and the larger at the bottom of the caudal sac. The second compartment comprises a mere six percent of the gastric volume, (Mackie) and manifests stratified layers of squamous epithelium. The third compartment includes the pocket shaped duodenal ampulla and terminates with the duodenum. The gallbladder is absent in all lamoids.
While the chief habitat is rangeland of the broad steppes or high mountain plateaus, the Guanaco will also find use of hilly areas of the Andes as well as coastal terraces with tussock grasses such as along Seno Otway. In addition to grasses, the Guanaco also consumes lichens and fungi and is resourceful in arid lands in licking due from vegetation and rock crevices. The Puma is a principal top level consumer that has assisted in controlling Guanaco populations since prehistoric times.
Numerous micro-organisms are found in a Guanaco; some of these, especially certain protozoans and bacteria, are essential for digestion in the complex stomach. Coccidial protozoans are known to inhabit the digestive tract of Guanacos.
A number of parasites occur the Guanaco, a protozoan example being Sarcocystis tilopodi, which resides in muscle tissue. Presence of this protozoan has limited prior use of Guanaco as a human food source. (Roth) Sheep pinworm (oxyuridosis) also inflicts the guanaco, with the nematode Skrjabinema ovis invading the intestinal tract via ingestion by L. guanacoe of this worm's eggs.
A number of bacteria are have been isolated in Guanacos. Leptospira bacteria, for example, are documented to affect some Guanaco individuals. Species of pleomorphic bacteria within the genus Rickettsia are also found in L. guanacoe; these obligate intracellular bacteria can present in coccal, bacchilis or thread-like forms.
Guanacos form small herds typically containing five to 50 individuals, with a breeding herd being much smaller than a bachelor herd. A breeding herd includes one dominant male will typically band with several females and the herd offsring, while unsuccessful males will form bachelor herds. Young males are typically driven away from the herd by age one. The sole Guanaco predator , besides man, is the Puma. If pursued, the Guanaco can reach a peak land velocity of 50 to 55 km/hr and is also a good swimmer. When alarmed, herd members emit a rather high frequency bleating sound. If under serious close attack, the Guanaco may kick, bite or spit at an intruder.
The breeding season commences in November and continues to at least early February. In the initial part of the breeding season, adult males engage in combat to determine dominance and who will have breeding status. The Guanaco males have thick and durable skin to provide defence in the pre-mating combat rituals.
Estimates of the pre-transoceanic contact period Guanaco population range from seven to 20 million. Intense hunting for pelts (Ray) and Guanaco population reduction by increasing livestock grazing has severely diminished the number of animals to a present day value of 400,000 to 600,000. The prehistoric range for L.guanacoe included large elements of the Chaco Plain in Paraguay and many inland portions of Bolivia, where only smaller remnant populations exist today.(Mares)
Present threats to the Guanaco population include: (a) large scale ongoing intrusion into native rangeland for sheep cultivation, (b) competition for forage with invasives such as European red deer and (c) prey-switching enhancement of puma populations by the excessive numbers of such exotic herbivores. Of greater concern, there is a less than expected rebound of Guanaco populations in experimental areas where sheep grazing is reduced; these disappointing results may be explained by a more permanent degradation in rangeland following intensive grazing of sheep and the prey-switching phenomenon outlined above. My observations of rangelands in the Chilean and Argentinian Patagonian steppes indicate that many ongoing sheep grazing operations are sufficiently intensive to accelerate erosion and topsoil loss, leading to long term productivity reduction of the grasslands.
* Justina C. Ray, Kent H. Redford, Robert Steneck and Joel Berger (2005) Large Carnivores and the Conservation of Biodiversity: Biodiversity, Island Press, 526 pages ISBN 1559630809
* C. Michael Hogan (2008) Magellanic Penguin, GlobalTwitcher.com, ed. N. Stromberg
* Rod I. Mackie, Bryan A. White, Richard E. Isaacson (1997) Gastrointestinal Microbiology: Gastrointestinal Ecosystems and Fermentations, Published by Springer, 676 pages ISBN 0412983613
* Harald H. Roth and Günter Merz (1997) Wildlife Resources: A Global Account,
Published by Springer, 403 pages ISBN 3540613579, 9783540613572
* Michael A. Mares and David J. Schmidly (1991) Latin American Mammalogy: History, Biodiversity, and Conservation, University of Oklahoma Press, 468 pages ISBN 0806123435