Tarbagan marmots, Marmota sibirica, also known as Siberian marmots, are found primarily in Mongolia. There are two subspecies of this taxon, Marmota sibirica sibirica and Marmota sibirica caliginosous. Within Mongolia, M. s. sibirica lives on the eastern steppes and the Hentii mountain range. M. s. caliginosous occupies the northern, western, and central regions of Mongolia, as well as the Hangai, Hövsgöl, and Mongol Altai mountain ranges. Outside of Mongolia, Tarbagan marmots live in parts of China, such as Nei Mongol and Heilongjiang, and parts of Russia, including Siberia, Tuva, and Transbaikalia. (Batbold, et al., 2008; Smith and Xie, 2008)
Tarbagan marmots require habitats with ample vegetation for grazing, such as grasslands, shrublands, mountain steppes, alpine meadows, open steppes, forest steppes, mountain slopes, semi-deserts, river basins, and valleys. They are found altitudes ranging from approximately 600 to 3000 m above sea level. Tarbagan marmots occasionally forage at higher elevations when vegetation is scarce.
The two subspecies typically reside at different elevations. Marmota sibirica sibirica occupies lower steppes and grasslands while M. s. caliginous occupies higher mountain ranges and slopes. At extremes, these marmots are known to reside in alpine fields at 3800 meters. (Batbold, et al., 2008; Clark, et al., 2006)
Tarbagan marmots are rodents with stout bodies and short limbs. They weigh between 6 and 8 kg and measure 50 to 60 cm in length. Their tails are bushy and approximately one half of their body length.
Their fur is primarily brown in color, medium length, and fine in texture. Dorsally, the fur is light brown to light rusty colored, often with hints of light, whitish yellow. The color of the fur undergoes minor seasonal changes, from light grayish brown in the spring to reddish brown in late autumn. The fur on the rostrum and around the eyes as well as the tail is darker brown. The ears are light orange-brown. (Allen, 1940; Batbold, et al., 2008; Cardini, 2003; Smith and Xie, 2008)
Marmota sibirica has robust post-orbital processes. The lateral side of the anterior zygomatic arch is lozenge-shaped. The crown of the second upper premolar and the crown of the first molar are equal in size, but are both smaller than the crowns of the last two molars. One of the most important skeletal features of this species is the mandible, both in size and shape. This feature helps to place the species within morphologically-based phylogenetic trees. The mandible size is also extremely sexually dimorphic for the species, with males having significantly larger mandibles than females.
Marmota sibirica and M. baibacina (gray marmots) have extremely similar mandibles, and this similarity has been put forth as evidence for a close phylogenetic relationship between the two taxa. The two species also have similar external characteristics and are believed to have hybridized at some point. However, gray marmots are larger than Tarbagan marmots, and they lack the pronounced sexual dimorphism in the mandible. (Allen, 1940; Batbold, et al., 2008; Cardini, 2003; Smith and Xie, 2008)
Tarbagan marmots mate in-group, meaning they reproduce with individuals from the extended family colonies in which they live. The marmots pair off within their colony to reproduce, forming either monogamous or polyandrous relationships. (Batbold, et al., 2008; Wolff and Sherman, 2007)
Tarbagan marmots traditionally breed every other year in April after a successful yield of offspring. Gestation lasts approximately 40 to 42 days. Births occur at the end of May, and young emerge from the burrow in June. Litter size is usually between 4 and 6, but Tarbagan marmots can produce litters of up to 8 offspring. Weaning of other species in the genus Marmota lasts from 28 to 46 days.
In any given year, the percentage of females who reproduce ranges from 17 to 77%, although usually no more than 50% reproduce. During years with abundant rainfall, a higher percentage of females reproduce.
Tarbagan marmots exhibit a unique behavior called delayed reproduction. They are capable of reproduction much earlier than when they actually do. This ability is measured by the maturity index, which is a ratio of a particular organism's current size to the size of a mature adult. At a maturity index of 0.65, Tarbagan marmots should be able to reproduce. Instead, females usually reproduce at the age of 2, at which time their maturity index is greater than 0.65. (Allen, 1940; Armitage, 1999; Batbold, et al., 2008; Blumstein and Armitage, 1999; de Magalhaes and Costa, 2009)
Although weaning of marmots usually occurs between 28 to 46 days, Tarbagan marmots are present in their offspring’s lives for 3 years. Marmota sibirica undergoes delayed dispersal, a behavioral trait that leads juveniles to stay with their natal group for longer than necessary. They do not leave their parental burrows until at least 3 years of age. Other members of the extended family colony provide parenting as well, primarily in the form of group hibernation in the winter. This alloparental care increases overall species survival. (Armitage, 1999; Blumstein and Armitage, 1999; de Magalhaes and Costa, 2009)
Little is know regarding the lifespan of Tarbagan marmots. Lifespan of other species in the genus Marmota ranges from 13 to 15 years in the wild (M. bobak, M. marmota, M. flaviventris) and from 7 to 21 years in captivity. (de Magalhaes and Costa, 2009)
Tarbagan marmots are social animals, living in large colonies of their extended family. This extended family is comprised of a dominant adult pair, subordinate adults, and all of their yearlings (offspring that have yet to be dispersed). Family behavior is largely determined by external factors. In favorable conditions, Tarbagan marmots live in long-lasting, stable families of 13 to 18 individuals. Unfavorable conditions produce unstable, short-lived families of 2 to 6 marmots. Tarbagan marmots are socially integrated in the summer, only separating for a short time. Population density can be influenced by the timing of vegetation growth; the earlier the vegetation begins to grow, the denser the marmot population.
Tarbagan marmots are very territorial. In an area of sympatry of Marmota sibirica and Marmota baibacina, Tarbagan marmots forced the other species into bouldery screes. Through this territorial behavior, they were able to freely inhabit the most advantageous habitats. While remaining territorial, Tarbagan marmots were found to coexist in the same territories as Marmota baibacina. This supports the theory that these two species occasionally live in mixed families, implying an increased chance of hybridization.
Tarbagan marmots hibernate in the fall, using their burrows for protection. They use dirt, sticks, feces, leaves, and urine to seal their burrows during hibernation. Length of hibernation is influenced by weather and summer food conditions.
Because of their relatively large body size and short active season, Tarbagan marmots exhibit a behavior called delayed dispersion. The growing season after birth is very short, and juveniles cannot reach a maturity index that would allow them to successfully disperse before their first hibernation. They require an additional summer to reach this maturity index. However, by that time, the individuals have become solidified in a social group. They are dominated by older marmots in the extended family colony, causing them to suppress reproduction and participate in alloparental care of offspring. This care comes primarily in the form of group hibernation (social thermoregulation). When they finally have the opportunity to reproduce, they are well beyond sexual maturity. Tarbagan marmots usually disperse at age three.
Some studies concluded that Tarbagan marmots prefer to maintain a home range of 3 to 6 ha, but will live in 2 ha unfavorably. Other studies indicate that they live in 1.7 ha. This variation is due to available vegetation. When resources are scarce, Tarbagan marmots are more likely to expand their range to search for food. (Armitage, 2000; Batbold, et al., 2008; Blumstein, et al., 2001)
One of the most important modes of communication of Tarbagan marmots is their alarm call. The acoustic makeup of their alarm call is unique to this species and has been used to distinguish them from other kinds of marmots, particularly Marmota baibacina.
Tarbagan marmots are herbivorous and have a fairly simple diet, which consists largely of grasses. Additionally, they eat 10 to 15 types of herbs as well as wood plants like sagebrush. Cellulose content of a typical diet is 20 to 25%. When this cellulose content is too high, food consumption and assimilation decreases.
In order to forage for fresh vegetation, Tarbagan marmots often climb higher to reach unspoiled food supplies. After hibernation and for the first half of their active season, they primarily eat grasses and some herbs. During the second half of their active season, however, they eat mostly herbs. For this reason, habitats completely dominated by grasses are not preferred. (Armitage, 2000; Batbold, et al., 2008)
The most common predators of Tarbagan marmots are wolves, red foxes, hawks, buzzards, brown bears, snow leopards, and eagles. Tarbagan marmots have a variety of anti-predator adaptions. Their fur is usually a brownish color that blends in with the soil of their habitats. They emit alarm calls to warn others of the presence of predators. They also burrow to keep themselves and their young safe. Juveniles experience the greatest mortality, as they often play around the burrows in the early summer, leaving them exposed to predators. Older marmots are shy and more adept at slipping back into their burrows at the sign of predation. (Allen, 1940; Batbold, et al., 2008; Clark, et al., 2006)
Tarbagan marmots are keystone species, playing a vital role in the biogeographic zones they occupy.
In the arid steppe habitat, burrows of Tarbagan marmots are used by corsac foxes, Vulpes corsac. Although capable of making burrows, use of pre-existing marmot burrows enhances survival, as this behavior is an energy-efficient adaption to their environment, which is characterized by fluctuating food resources. As populations of Tarbagan marmots decline, it is believed that populations of corsac foxes will also decline.
When burrowing, Tarbagan marmots create mounds with unique vegetative characteristics that vary with level of disturbance. These mounds are usually dominated by one species of plant. In a Stipa steppe in Mongolia (a common habitat of Tarbagan marmots), vegetation mounds were commonly comprised of Stipa krylovii, Artemisia adamsii, and Leymus chinensis. With increased marmot disturbance, species richness decreased in vegetation mounds, especially in those dominated by Leymus and Artemisia. However, this marmot behavior led to better forage quality in Leymus and Artemisia mounds.
Tarbagan marmots host a variety of parasites, including fleas (Ceratrophyllus silantievi), ticks (Rhipicephalis), and tapeworms (Ctenotaenia marmotae). (Allen, 1940; Armitage, 2000; Batbold, et al., 2008; Blumstein, 2002; Ganzorig, et al., 2007; Murdoch, et al., 2009; Van Staalduinen and Werger, 2007)
Local populations of Mongolian herders use the meat of Tarbagan marmots for food and their body parts for medicine. Oil from Tarbagan marmots is harvest, as it contains high levels of corticosterone and is traditionally used as a leather conditioner, dietary supplement, and a remedy for burns, frostbite, anemia, and tuberculosis. Furs are used locally and sold for profit in national and international trade. Sport hunting of Tarbagan marmots also occurs. (Batbold, et al., 2008; Clark, et al., 2006)
Tarbagan marmots are vectors of the bubonic plague (Yersina pestis). They have been known to cause outbreaks in their environments, as they can carry the disease when infected with parasites such as Certrophyllus silantievi (fleas) and ticks of the genus Rhipicephalis. An outbreak of the plague in 1911 caused the deaths of 50,000 natives, and an outbreak in 1921 caused 9,000 deaths. Both outbreaks have been attributed to disease-carrying Tarbagan marmots. Recent studies have determined that infected marmots need not be spread out over a large area to to cause a wide-scale impact. Humans can also contract the plague by eating diseased meat. Some populations of Tarbagan marmots develop a rapid genetic immunity to the plague, indicated by higher body temperature. (Allen, 1940; Armitage, 2000; Batbold, et al., 2008; Blumstein, 2002; Elton, 1925)
Tarbagan marmots are considered endangered by the IUCN. The population has been experiencing a long term decline, and 70% of the population was lost in the 1990s. This decline is primarily attributed to exploitation by human enterprise (food, fur, sport) and disease (the plague). Most notably, Tarbagan marmots have been hunted vigorously for their skins. Between 1906 and 1994, 104.2 million skins were prepared in Mongolia alone. Additionally, fear of the plague has led to massive extermination campaigns, removing both infected and healthy marmots.
Tarbagan marmots in Russia are particularly threatened, as they rarely occur in the wild. This species is protected under the Mongolian Protected Area Laws and Hunting Laws, though these laws do not specifically focus on Marmota sibirica. (Batbold, et al., 2008; Clark, et al., 2006)
Harry VanDusen (author), Yale University, Eric Sargis (editor), Yale University, Rachel Racicot (editor), Yale University, Gail McCormick (editor), Animal Diversity Web Staff.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
an animal that mainly eats leaves.
A substance that provides both nutrients and energy to a living thing.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
An animal that eats mainly plants or parts of plants.
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.
Found in northern North America and northern Europe or Asia.
a species whose presence or absence strongly affects populations of other species in that area such that the extirpation of the keystone species in an area will result in the ultimate extirpation of many more species in that area (Example: sea otter).
parental care is carried out by males
Having one mate at a time.
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
the area in which the animal is naturally found, the region in which it is endemic.
Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
digs and breaks up soil so air and water can get in
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5? N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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