Dromiciops gliroides (monito del monte) is found in southern South America, specifically the northern portions of Patagonia, between 36 and 43 degrees South latitude. In addition to mainland South America, it is found on Chiloe Island. (Patterson and Rogers, 2007; Rodriguez-Cabal, et al., 2008)
Dromiciops gliroides is found in temperate forests and rainforests. It is mainly found in old-growth Nothofagus forests, but can be found in a variety of habitats ranging from dense thickets of bamboo (Chusquea spp.) to open, secondary forests. (Nowak, 1999; Patterson and Rogers, 2007; Rodriguez-Cabal, et al., 2008)
A study of small mammals at elevations from 425 to 1135 m above sea level in Chile found that Dromiciops gliroides was captured more often at higher elevations (between 820 and 1135 m) than at lower elevations (425 to 715 m). (Patterson, et al., 1989)
Monitos del monte are small, mouse-like marsupials. Body length (excluding the tail) is between 83 and 130 mm; the tail is between 90 and 132 mm long. This species weighs between 16 and 42 g. (Nowak, 1999)
They are superficially mouse-like, with a short rostrum and small, rounded ears. The pelage is short and dense. While the majority of the body is brown to gray in color, white patches can be found on the shoulders and rump. Ventral pelage is lighter in color than dorsal pelage, and ranges from yellowish white to pale gray. Although a whorling pattern is sometimes visible, the most distinct pelage characteristic is the pronounced black eye rings. The tail is moderately prehensile and well-furred, except for a 25 to 30 mm naked underside portion which may improve traction when the animal grasps tree branches. (Beer, 2003; Marshall, 1978; Nowak, 1999)
Seasonal variation and sexual dimorphism has been observed in Dromiciops gliroides. A study of monitos del monte in Patagonia found that, by the end of summer, females are significantly heavier and longer than males. Although both sexes use their tails are storage organs, females tend to have thicker tails; this suggests that females have higher energy needs during times of hibernation or torpor. While variation in tail thickness is seasonal, it is unclear if females are larger than males year-round. (Rodriguez-Cabal, et al., 2008)
Geographic variation has also been reported in this species. Previously, two subspecies were recognized based on geography. Mainland monitos del monte were referred to Dromiciops australis australis and those from Chiloe Island were referred to Dromiciops australis gliroides. However, the only noticeable difference in appearance between these types is that island monitos del monte have darker pelage. Due to insufficient distinguishing characters between mainland and island populations, separate subspecies are no longer recognized as distinct. (Patterson and Rogers, 2007)
Monitos del monte become sexually mature after their second year and breed in the austral spring (August to September). Breeding pairs form shortly beforehand. They are not known whether these pairs persist after mating. (Marshall, 1978; Munoz-Pedreros, et al., 2005)
Monitos del monte typically reach sexual maturity at age 2 and breed once yearly. Males and females form pairs and mate in August or September. Before parturition occurs, females construct small, rounded nests (about 200 mm in diameter) from sticks and water-repellent bamboo. These nests are located 1 to 2 m above the ground. Young are born approximately 3 to 4 weeks after conception and climb into the well-developed, anteroventral opening of the marsupium, where they remain attached to one of the four teats for approximately 2 months. Litters of up to 5 young have been reported, but females are unable to feed more than 4 offspring at a time. Although the young begin to exit the marsupium for short durations beginning in December, they do not become completely independent until March. (Munoz-Pedreros, et al., 2005; Nowak, 1999)
Female monitos del monte suckle their altricial young for approximately 5 months (from early November to late March). Prior to the independence of offspring, females carry them in the marsupia or on their backs during "nocturnal family excursions." (Munoz-Pedreros, et al., 2005)
Monitos del monte are marsupials with nocturnal habits. They are arboreal or scansorial and uses their prehensile tail, large hands and feet, and opposable hallux to climb trees. Although typically regarded as rare, they may be underrepresented in capture studies due to their avoidance of closed, box-type traps. (Kelt and Martinez, 1989; Marshall, 1978)
Changes in ambient temperatures and food availability can induce spontaneous torpor in monitos del monte. They can exhibit daily fluctuations in body temperature and metabolic rate and are capable of shallow, short term torpor. Decreased ambient temperatures, coupled with decreased food cause deep, prolonged torpor (hibernation); this typically occurs during the winter and spring. This behavior is a flexible adaptation to unpredictable and potentially cold, harsh conditions. It also enables monitos del monte to conserve energy and avoid costly foraging when resources are limited. (Bozinovic, et al., 2004)
The home range and territory size of Dromiciops gliroides are not known. A study of monitos del monte in Patagonia estimated a summer population size of 54 individuals based on capture-mark-recapture methods. (Rodriguez-Cabal, et al., 2008)
Monitos del monte communicate via sound. At night they produce trilling calls that end in a coughing noise as well as buzzing noises. Other modes of communication are not known. Similarly, although males and females form pairs during the breeding season, population and social structure during other times of the year are unknown. (Beer, 2003; Marshall, 1978; Rodriguez-Cabal, et al., 2008)
Monitos del monte are primarily insectivorous, eating insects, larvae, and pupae found on tree branches and in crevices in bark. Moths and butterflies (Lepidoptera) also make up a large part of their diet. During the austral summer, monitos del monte consume large quantities of mistletoe (Tristerix corymbosus) fruits and other fleshy fruits.
In captivity, monitos del monte eat a wide variety of food, including fruits, vegetables, potatoes, oats, invertebrates, vertebrates, meat, fish, eggs, and cheese. (Amico, et al., 2009; Beer, 2003; Kelt and Martinez, 1989; Marshall, 1978; Rodriguez-Cabal, et al., 2007)
Predators of Dromiciops gliroides include native and introduced birds and mammals, particularly domestic cats (Felis catus). Studies have estimated that monitos del monte make up 10% of the diet of gray foxes (Lycalopex griseus), 3.6% of the diet of Darwin's foxes (Pseudalopex fulvipes), and a small portion of the diet of barn owls (Tyto alba). Monitos del monte produce strong smelling secretions from cutaneous glands, which may deter predators. They also exhibit a threat posture with teeth exposed, particularly if aroused from torpor. (Jaksic, et al., 1990; Kelt and Martinez, 1989; Marshall, 1978; Rau, et al., 1995; Rodriguez-Cabal, et al., 2007; Trejo and Ojeda, 2004)
In the temperate forests of Patagonia, Dromiciops gliroides is the sole seed dispersal agent of the mistletoe Tristerix corymbosus. The seeds pass undamaged through the digestive tract and are deposited directly onto the bark of host trees. In fact, passage though the gut of D. gliroides is necessary for the seeds to germinate and important for seedling recruitment. This mutualism may have evolved over the last 70 million years, and remains important for biodiversity today. Field observations and captivity studies also found that D. gliroides is capable of dispersing the seeds of the majority of fleshy fruit-producing plant species in the region, including Aristotelia chilensis and Azara microphylla; other small mammals destroy the seeds they consume from these plant species. Mistletoe, a parasitic climbing plant species, is important for maintaining understory plant diversity and facilitating ecosystem processes such as nutrient cycling. Additionally, nearly 100 families of birds and mammals rely on mistletoe for fruit, nectar, and nesting material. Disruption of the mistletoe-monito del monte mutualism could cause extinctions, decreased biodiversity, and increased community susceptibility to drought. (Amico and Aizen, 2000; Amico, et al., 2009; Garcia, et al., 2009; Watson, 2001)
Monitos del monte play a key role in seed dispersal for fleshy fruit-producing plants in temperate forests; these mutualisms are important for the maintenance of biodiversity. Monitos del monte may also be important for reducing insect pests. (Amico, et al., 2009; Beer, 2003; Watson, 2001)
In Chile, there are several superstitions about Dromiciops gliroides. For example, monitos del monte are erroneously described as bad luck, venomous, and causes of disease. In extreme cases, people have burned their houses down after seeing monitos del monte in their places of residence. However, monitos del monte have no negative effects on humans. (Beer, 2003; Marshall, 1978)
Although currently classified as near threatened on the IUCN Red List, Dromiciops gliroides is threatened by an increasing number of anthropogenic activities. The introduction of species such as domestic cats (Felis catus), deforestation, and cattle grazing are associated with decreased abundances of monitos del monte and habitat fragmentation. A study of forest fragmentation found that human activity can reduce preferred tree types and increase susceptibility to predation. Monitos del monte, like many small mammals, are unable to cross even small deforested areas. Monitos del monte are also hosts to blood parasites (Hepatozoon) and ticks (Ixodes neuquenensis), which can further reduce the numbers of these important marsupials. (Amico, et al., 2009; Marin-Vial, et al., 2007; Rodriguez-Cabal, et al., 2007; Merino, et al., 2009)
Dromiciops gliroides belongs to the most geographically restricted order of extant mammals. The monito del monte is called a "living fossil" because it is the single extant representative of the microbiothere lineage. The oldest microbiothere may be a Khasia species, a fossil from Bolivia between 60.4 and 59.2 million years old. (Amico and Aizen, 2000; Beer, 2003; Bozinovic, et al., 2004; Meredith, et al., 2008; Spotorno, et al., 1997)
Dromiciops gliroides is more closely related to Australian marsupials than American ones. Two recent phylogenetic studies, one based on 5 nuclear genes and the other on 7 nuclear genes and 15 mitochondrial genes, concluded that Dromiciops is a sister group to all other australidelphians (members of the orders Peramelemorphia, Notoryctemorphia, Dasyuromorphia, and Diprotodontia). Microbiotheria likely diverged from this Australasian clade approximately 67.4 million years ago. Although morphological studies nest Dromiciops within the Australasian clade as well, many of the morphological characters are believed to be homoplasious or plesiomorphic. (Beck, 2008; Meredith, et al., 2008; Sanchez-Villagra, et al., 2007)
Jennifer Chick (author), Case Western Reserve University, Darin Croft (editor, instructor), Case Western Reserve University, Tanya Dewey (editor), Animal Diversity Web.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
Referring to an animal that lives in trees; tree-climbing.
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.
an animal that mainly eats meat
uses smells or other chemicals to communicate
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.
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.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
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.
An animal that eats mainly insects or spiders.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
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).
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
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).
Living on the ground.
uses sight to communicate
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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