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Monito del monte or colocolo (Dromiciops gliroides)The monito del monte (Spanish for "little mountain monkey") is a small marsupial from thickets of mountain bamboo in the dense, cool, humid Valdivian temperate rain forests of the southern Andes of Chile and Argentina. It occurs from the vicinity of Concepción south to Chiloe Island in south-central Chile and east to the provinces of Neuquen and Rio Negro in Argentina. It has been reported from Maule region in Los Queules National Reserve and Reserva Nacional Los Ruiles, about 200 km north of its known distribution near Concepción. The populations in this region are thought to be very small and possibly relictual, as the species is thought to have migrated further south at the end of the last Ice Age glaciation. It is only slightly larger than a mouse. The body length is about 83-130mm, the tail is about 90-132mm and the weight is about 16-42 g. It has short, dense, silky fur which is brown above, with some ashy white patches, and paler below. The ears are short and furry and there are black rings around the eyes. The tail is covered with hairs that match the body colour at the base and become darker brown towards the tip. It is nocturnal and is an excellent climber, using its partially prehensile tail. It mainly lives in trees, but it may shelter underground, under rocks or fallen tree trunks. It sleeps in small, spherical nests of sticks and water-resistant bamboo and colihue leaves, which it lines with moss or grass and places in well protected areas of the tree, such as hollow trees or on branches, or suspended in lianas or patches of bamboo. The nests may be covered with grey moss as camouflage. These nests protect the animal from the cold, when it is active and when it hibernates in winter. The animal stores fat in the base of its tail to help it hibernate during the winter when food is scarce; it can double its weight in a week. It is thought to hibernate for up to six months in winter, but some animals have been found torpid at other times of the year. Its diet of insects and other small invertebrates is supplemented with fruit. There is a mutualistic seed dispersal relationship between the monito del monte and the Loranthacous mistletoe. The monito del monte is the only dispersal agent for this plant, which would probably become extinct without it. The animal eats the fruit and thus disperses the seeds. Scientists think the coevolution of the two species could have begun 60–70 million years ago.
The species is thought to live in pairs, at least during the mating season (October-December). The animals reproduce aggressively, sometimes leaving blood on the reproductive organs. . Females can have litters of one to five young from November to May. Females have a pseudovagina and a well-developed, fur-lined pouch containing four mammae. When the young are mature enough to leave the pouch, they are nursed in the nest and then carried on the mother’s back during nocturnal foraging trips. They remain in loose association with the mother even after they are weaned. Both sexes reach sexual maturity in their second year. The lifespan of this species in the wild is thought to be around 2 years.
It is classified as Vulnerable (VU A1c) on the 2006 IUCN Red List of Threatened Species. The total population is decreasing, mainly due to habitat loss and fragmentation, with native forests being replaced with introduced conifers. Habitat protection is the main conservation measure needed. The animal is also threatened by the black rat. The monito del monte occurs in the Valdivian Coastal Reserve, which is managed by WWF, Conservation International (CI), the Nature Conservancy in Chile, and various local partners. It has also been reported from Los Queules National Reserve and Reserva Nacional Los Ruiles. One project aims to evaluate the use of the monito del monte as an indicator species for fragmented forests. ]
Superstitious native people are scared of the monitos del monte and may burn down their houses when they see one inside. ]
Scientists regard the monito del monte as a living fossil, because it is the only surviving member of an otherwise extinct lineage, the Family Microbiotheriidae in the ancient order Microbiotheria, dating back over 40 million years. Related fossil species date back to the early Paleocene of Bolivia (almost 65 million years ago). The monito del monte was once thought to be a member of the opossum family, Didelphidae. It is the only living species in and the only New World representative of the superorder Australidelphia (all other New World marsupials belong to the Ameridelphia). It was long suspected that South American marsupials were ancestral to those of Australia as the two continents were connected via Antarctica in the early Cenozoic. Australia’s earliest known marsupial is the primitive, mouse-like Djarthia, which lived about 55 million years ago. Djarthia was identified as the earliest known australidelphian and suggested that the monito del monte was the last of a clade which included Djarthia. This implied that the ancestors of the monito del monte might have reached South America via a back-migration from Australia. The time of divergence between the monito del monte and its closest Australian relatives (Peramelemorphia, Dasyuromorphia and Notoryctemorphia) was estimated at 46 million years ago. This coincides with the geological separation of Antarctica and Australia, suggesting that the phylogenetic divergence occurred as a result of geographical separation. In 2010, analysis of retrotransposon insertion sites in the nuclear DNA of various marsupials confirmed the placement of the monito del monte in the Australidelphia, but showed that its lineage is the most basal of the superorder. The study confirmed that the most basal of all marsupial orders are the other two South American lineages (Didelphimorphia and Paucituberculata), with the former probably branching first). This indicates that Australidelphia arose in South America (with the ancestors of all other living marsupials) and probably reached Australia in a single dispersal event after Microbiotheria split off.