Monito Del Monte

## Background Information

### Alternate Name(s)

Little monkey of the mount, Southern monito del monte, Colocolo opossum, Chimaihuén

## Classification

### Subspecies

D. g. gliroides (formerly)
D. g. australis (formerly)

The monito del monte ***(Dromiciops gliroides)*** or colocolo opossum, is a small marsupial native to southwest South America. The Spanish name "monito del monte" directly translates to "little monkey of the mount" in reference to the species' habitat and arboreal lifestyle. Monitos del monte can be brown, tan or grey in colour, they have short faces, rounded ears and superficially resemble mice, with similar tails, limbs and other features. Unlike mice however, their tails are semi-prehensile and also furred, with the exception of the underside. They also have white or light grey underbellies to act as camouflage, using the method of countershading popular with arboreal and aquatic species. Black rings around the eyes are also apparent. In comparison to other similar small marsupial species, monitos del monte have shorter limbs with more robust hands and feet, as well as more-furred ears. Two subspecies of the monito del monte, ***(D. g. australis)*** and ***(D. g. gliroides)*** inhabit the mainland and the island of Chiloé respectively however, the subspecies exhibit little differences to the monito del monte outside of ***(D. g. gliroides)*** possessing a darker coat. Due to this fact, the two subspecies are no longer considered separate to the monito del monte. The order in which the monito del monte belongs to; Microbiotheria, is actually an ancestral order to Australian marsupials and dasyurid marsupials in specific and the monito del monte is only one of two surviving members22. This means that the species closest relatives are Australasian marsupials rather than American marsupials such as opossums. Because of the monito del monte's long and complex evolutionary history and the fact that it likely still upholds the same niche as its ancestors on Gondwana, scientists have long seen the species as a 'living fossil' or 'relict species'. Today, it gives the zoological and paleontological communities a way of looking into the past and witnessing how extinct marsupials may have acted in life, making the monito del monte an incredibly important species in environmental science. Monitos del monte can reach anywhere between 83-130mm (3.27-5.12in) (including the tail) and can weigh between 16-42g (0.56-1.48oz). Seasonal variation and sexual dimorphism have also been documented (discussed in Behaviour).

## Diet

Monitos del monte are omnivores, consuming various insect species and occasionally fruits. As a partially insectivorous species, monitos del monte hunt and eat larvae, pupae, moths and also butterflies. They forage in trees, mostly searching through cavities and crevasses. They are also known to eat fleshy fruits prolifically, particularly in the summer months when they are abundant. Monitos del monte are actually a keystone species, greatly aiding the dispersal of fruit trees. Mistletoe ***(Tristerix corymbosus)*** is the most commonly dispersed by the species, the seeds being deposited into the bark of other tree species through defecation. It is actually necessary for the seeds of this plant to move through the monito del monte's digestive tract, as this is its method of germination. The monito del monte is sole depositor of these species. In captive environments monitos del monte consume a much wider and vastly different diet, being fed multiple fruits and vegetables, grains such as oats, meat products including fish, eggs and also cheese.

## Conservation Status

Despite the IUCN regarding the species as near-threatened, the monito del monte suffers a variety of human-caused threats. Deforestation and habitat alteration is the largest contributor to the current decrease in population numbers. Through these actions, favoured tree species are rendered unavailable and populations may face fragmentation, as monitos del monte have difficulties crossing unnatural barriers such as roads and other forms of harmful human infrastructure. Invasive species also pose a threat to the monito del monte, with domestic and feral cats ***(Felis catus)*** in particular hunting monitos del monte in areas of low tree density as a direct result of human activity. Lastly, the species is susceptible to blood parasites and ticks, which have led to increased mortality.

## Range and Population

Monitos del monte inhabit the montane and temperate forests of southwest Chile (including Chiloé island) and Argentina, occurring mostly in Patagonia. Monitos del monte are mountainous in nature and can be found at elevations of 425-1,135m (1,394.36-3723.75ft), with an abundance of individuals being observed at the extent of this range. The population of the species is unknown currently however, it is in decline, with the species being considered rare throughout its range.

## Behaviour

As an arboreal marsupial, the monito del monte spends the majority of its time in tree canopies, utilising its prehensile tail, dexterous feet and opposable halluces (the innermost digit of the hind legs) to traverse treetop environments. Quite uniquely monitos del monte may exhibit forms of torpor (prolonged lethargy) in low temperature or food scarce environments, which can even result in extended periods of torpor, most commonly likened to hibernation. This is characteristic of the monito del monte as they are one of few marsupial species to exhibit this behaviour. In use, this behavioural adaptation allows monitos del monte to remain sedentary in dire environments and avoid the need to forage constantly. They usually go into "hibernation" during winter-spring. A nocturnal species, the monito del monte is most active at night. During this time, individuals can be heard communicating to each other across the forest through shrill call that ends in a short coughing bark or buzzing call. It is unknown whether this species communicates in non-audial forms. After reaching sexual maturity at age 2, monitos del monte will form male-female breeding pairs from August to September. The social structure of the species is unknown outside this yearly time frame. Before giving birth, the female monito del monte creates a small rotund nest -typically consisting of leaves, twigs, mosses and water repellent bamboo species-, up to 2m (6.6ft) from the ground. After a gestation of 3-4 weeks, the young will climb from the anteroventral opening and into the mother's pouch, where they will feed off one of her four teats for the following 2 months. The young may emerge from the pouch in December however, will not be independent from their mother until March. During this period, the young will still nurse from their mother however she will also carry them on her back until their independence.

### Relationship with Humans

In Chilean superstition, a monito del monte's presence is said to harbour bad luck, as they are thought to be venomous and disease carrying by some. Though in reality monitos del monte are completely harmless, in some reported cases, people have burnt their homes down after seeing a monito del monte in or around their residence.

## In Captivity

No monitos del monte exist in captivity currently however, when the species was kept in captivity in the past, it only lived for 26 months, either suggesting a naturally short lifespan, or a decreased lifespan in a captive environment.

## Sources

* IUCN Red List of Threatened Species - https://www.iucnredlist.org/species/6834/22180239
* Monito Del Monte | Animal Diversity web, University of Michigan Museum of Zoology - https://animaldiversity.org/accounts/Dromiciops\_gliroides/
* The ecology and evolution of the monito del monte, a relict species from southern South America temperate forests | Wiley Online Library https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.8645
* Meet the tiny Patagonian monito that is a ‘living fossil’ from the ancient past | CNN - https://edition.cnn.com/2022/08/05/world/patagonia-monito-del-monte-scn/index.html
* Monito Del Monte | Encyclopedia of Life - https://eol.org/pages/129538/articles