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.
Known Predators:
Anti-predator Adaptations: cryptic
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.
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.
This species resembles Marmosa species, but possesses shorter limbs, more robust hands and feet, more semicircular upper incisors, and smaller, furrier ears.
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.
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.
Range mass: 16 to 42 g.
Range length: 83 to 130 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
Although the lifespan of Dromiciops gliroides in the wild is unknown, the longest lifespan in captivity is 26 months.
Range lifespan
Status: captivity: 26 (high) months.
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.
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).
Range elevation: 425 to 1135 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: forest ; rainforest
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.
Biogeographic Regions: neotropical (Native )
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.
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.
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.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
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.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: near threatened
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.
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.
Positive Impacts: controls pest population
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.
Ecosystem Impact: disperses seeds; keystone species
Mutualist Species:
Commensal/Parasitic Species:
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.
Animal Foods: insects; terrestrial non-insect arthropods
Plant Foods: fruit
Primary Diet: carnivore (Insectivore )
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.
Mating System: monogamous
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.
Breeding interval: Monitos del monte breed once yearly.
Breeding season: Monitos del monte breed in the austral spring (August to September).
Range number of offspring: 1 to 5.
Range gestation period: 3 to 4 weeks.
Average weaning age: 5 months.
Average time to independence: 5 months.
Range age at sexual or reproductive maturity (female): 1 to 2 years.
Range age at sexual or reproductive maturity (male): 1 to 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Average number of offspring: 3.
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."
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
The monito del monte or colocolo opossum,[4] Dromiciops gliroides, also called chumaihuén in Mapudungun, is a diminutive marsupial native only to southwestern South America (Argentina and Chile). It is the only extant species in the ancient order Microbiotheria, and the sole New World representative of the superorder Australidelphia (all other New World marsupials are members of the paraphyletic Ameridelphia). The species is nocturnal and arboreal, and lives in thickets of South American mountain bamboo in the Valdivian temperate forests of the southern Andes,[1] aided by its partially prehensile tail.[5] It eats primarily insects and other small invertebrates, supplemented with fruit.[5]
Dromiciops gliroides is the sole extant member of the order Microbiotheria.[3] It was first described by British zoologist Oldfield Thomas in 1894.[2] The generic name Dromiciops is based on the resemblance of the monito del monte to the eastern pygmy possum (Cercartetus nanus), one of the synonyms of which is Dromicia nana. The specific name gliroides is a combination of the Latin glis, gliris ("dormouse", more generally "rodent") and Greek oides ("similar to"). The name australis in a synonym (D. australis) refers to the southern distribution of the animal.[6] The common name monito del monte is Spanish for "little monkey of the bush".[7]
In his 1943 Mammals of Chile, American zoologist Wilfred Hudson Osgood identified two subspecies of the monito del monte:[8]
South American marsupials have long been suspected to be ancestral to those of Australia, consistent with the fact that the two continents were connected via Antarctica in the early Cenozoic. Australia's earliest known marsupial is Djarthia, a primitive mouse-like animal that lived in the early Eocene about 55 million years ago (mya). Djarthia had been identified as the earliest known australidelphian, and this research suggested that the monito del monte was the last of a clade that included Djarthia.[9] This relationship suggests that the ancestors of the monito del monte might have reached South America by back-migration from Australia. The time of divergence between the monito del monte and Australian marsupials was estimated to have been 46 mya.[5]
However, in 2010, analysis of retrotransposon insertion sites in the nuclear DNA of a variety of marsupials, while confirming the placement of the monito del monte in Australidelphia, also clarified that its lineage is the most basal of that superorder. The study further 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 conclusion indicates that Australidelphia arose in South America (along with the ancestors of all other living marsupials), and probably reached Australia in a single dispersal event after Microbiotheria split off.[10][11][12] Fossils of another Eocene australidelphian, the microbiotherian Woodburnodon casei, have been described from the Antarctic peninsula,[13] and fossils of a related early Eocene woodburnodontid have been found in Patagonia.[14]
Monitos del monte live in the dense forests of highland Argentina and Chile,[15][16][17][18] mainly in trees, where they construct spherical nests of water-resistant colihue leaves. These leaves are then lined with moss or grass, and placed in well-protected areas of the tree, such as underbrush, tree cavities, or fallen timber.[19] The nests are sometimes covered with gray moss as a form of camouflage. These nests provide the monito del monte with some protection from cold, both when it is active and when it hibernates.
Fragmentation of Valdivian temperate rainforests into non-contiguous areas is known to reduce the abundance of monitos del monte in a given area, but has little or no impact on whether it occurs in an area or not.[20]
Monitos del monte are small marsupials that look like mice. Dromiciops have the same dental formula as Didelphids: 5.1.3.44.1.3.4, a total of 50 teeth.[19] Their size ranges from 16–42 g (0.56–1.48 oz). They have short and dense fur that is primarily brown-gray with patches of white at their shoulders and back, and their underside is more of a cream or light gray color. Monitos del monte also have distinct black rings around their eyes. Their small furred ears are well-rounded and their rostrums are short. The head to body length is around 8–13 cm (3.1–5.1 in), and their tail length is between 9 and 13 cm (3.5 and 5.1 in). Their tails are somewhat prehensile and mostly furred with the exception of 25–30 mm (0.98–1.18 in) of the underside.[21] The naked underside of their tails may contribute to increasing friction when the mammal is on a tree. The base of their tails also functions as a fat storage organ which they use during winter hibernation.[22] In a week, Monitos del monte can store enough fat to double their body size.[19]
At the end of the summer, female Monitos del monte tend to be larger and heavier than males. The tails of the sexes also vary in size during this time; females have a thicker tail, which is where they store fat; the difference suggests that females need more energy than males during hibernation. The sexual dimorphism is only seen during this time and not year-round.[21]
Monitos del monte have a monogamous mating system. The females have well-formed, fur-lined pouch containing four teats. They normally reproduce in the spring once a year and can have a litter size varying from one to five. They can feed a maximum of four offspring, so if there are five young, one will not survive.[21] When the young are mature enough to leave the pouch, approximately five months, they are nursed in a distinctive nest. They are then carried on the mother's back. The young remain in association with the mother after weaning. Males and females both reach sexual maturity after two years.[3][23][24][25]
The monito del monte is adapted to arboreal life; its tail and paws are prehensile. It is largely nocturnal and, depending on the ambient and internal temperature, and on the availability of food, it spends much of the day in a state of torpor. Such behaviour enables it to survive periods of extreme weather and food shortage, conserving energy instead of foraging to no effect.
The animal covers its nest with moss for concealment, and for insulation and protection from bad weather.[21][26]
Monitos del monte are primarily insectivores. They eat insects and other invertebrates they find on the branches of trees and cracks in bark, but during the summer they eat large quantities of fruit, especially mistletoe fruit.[21]
A study performed in the temperate forests of southern Argentina showed a mutualistic seed dispersal relationship between D. gliroides and Tristerix corymbosus, also known as the loranthacous mistletoe. The monito del monte is the sole dispersal agent for this plant, and without it the plant would likely become extinct. The monito del monte eats the fruit of T. corymbosus, and germination takes place in the gut. Scientists speculate that the coevolution of these two species could have begun 60–70 million years ago.[27][28]
For the past few years the number of Dromiciops has declined, and the species is now classified as "near threatened". Many factors contribute to the decline:
The monito del monte is not the only organism which will be affected if it becomes endangered. Dromiciops illustrate parasite-host specificity with the tick Ixodes neuquenensis. This tick can only be found on the monito del monte, so it depends on the survival of this nearly endangered mammal.[19][29] T. corymbosus also depends on the survival of this species, because without the seed dispersal agency of the monito del monte, it would not be able to reproduce.
Currently, there are minimal conservation efforts. Ecological studies are being conducted in the Chiloé Island that might help future conservation efforts. Dromiciops has been found in the Los Ruiles National Reserve and the Valdivian Coastal Reserve, which are protected areas in Chile [26] and the Nothofagus forest of Parque Nacional Los Alerces, Chubut, Southern Argentina. [18]
The monito del monte or colocolo opossum, Dromiciops gliroides, also called chumaihuén in Mapudungun, is a diminutive marsupial native only to southwestern South America (Argentina and Chile). It is the only extant species in the ancient order Microbiotheria, and the sole New World representative of the superorder Australidelphia (all other New World marsupials are members of the paraphyletic Ameridelphia). The species is nocturnal and arboreal, and lives in thickets of South American mountain bamboo in the Valdivian temperate forests of the southern Andes, aided by its partially prehensile tail. It eats primarily insects and other small invertebrates, supplemented with fruit.
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