The tufted ground squirrel or groove-toothed squirrel (''Rheithrosciurus macrotis'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...

in the family Sciuridae. It is the sole species in the genus ''Rheithrosciurus''. It is found only on the island of

Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and eas ...

. Confirmed elements of its diet include nuts, seeds and insects, for which it has been filmed foraging on the forest floor.

Description

The squirrel's head and body measure about long, with the tail measuring a further long. It weighs about . Its incisors have 7-10 distinctive longitudinal grooves. Its skull is also distinctive, being longer and flatter than most squirrels. The animal's dorsum is predominantly brown with a reddish tone, and it has unusually hairy ears with large red to dark brown tufts. A longitudinal stripe of a white to buff to yellow colour, sometimes accompanied by a dark brown stripe, runs along the flank. ''Rheithrosciurus'' is noted for having the largest known tail to body size ratio of any mammal, with the volume of its tail including the air included in the fluff being 130% of the volume of its body. (Compare 90% for the

red squirrel The red squirrel (''Sciurus vulgaris'') is a species of tree squirrel in the genus ''Sciurus'' common throughout Europe and Asia. The red squirrel is an arboreal, primarily herbivorous rodent. In Great Britain, Ireland, and in Italy numbers ...

.) It is unclear why the squirrel has such a large tail but scientists have suggested that it may have evolved to distract predators or to prevent them getting a firm grasp when attacking. It may alternatively have a function in communicating with other squirrels or in courtship. Other possible explanations, such as being used to keep the animal warm or for balance, seem unlikely as the squirrel lives on the ground in a warm region. The tail has a grizzled charcoal colour with white frosting and rises in a plume, with the longest hairs at the tip.

Habitat

The species is known to live only on hillsides in lowland primary forest on the island of Borneo, at altitudes of under . It has occasionally been seen in orchards and secondary forests but sightings are rare. Due to deforestation it is considered to be vulnerable and is totally protected in

Sarawak Sarawak (; ) is a States and federal territories of Malaysia, state of Malaysia. The largest among the 13 states, with an area almost equal to that of Peninsular Malaysia, Sarawak is located in northwest Borneo Island, and is bordered by the M ...

, one of the two Malaysian states on Borneo. Hunting with a licence is legal in

Sabah Sabah () is a States and federal territories of Malaysia, state of Malaysia located in northern Borneo, in the region of East Malaysia. Sabah borders the Malaysian state of Sarawak to the southwest and the North Kalimantan province of Indone ...

, the island's other Malaysian state. Some natives use the squirrel's tail to decorate the hilt of their '' parang'' knives.

Natural history

''Rheithrosciurus'' is believed to forage on the ground and the lower canopy, holding its tail high over its head as it does so, and also climbs high trees to seek food. It appears to be diurnal in its habits. The squirrel is locally reputed to be a carnivore and has been dubbed the "vampire squirrel". According to forest-dwelling Dayak hunters, it attacks and kills deer to eat their stomach contents, liver and heart. The squirrel is said to achieve this by waiting on low branches, jumping on passing deer and biting their jugular veins to make them bleed to death. Once the deer dies, the squirrel eats the deer's internal organs. The hunters report occasionally finding deer disembowelled in this way and attribute them to "squirrel kills". It is also said to kill domestic chickens and eat their hearts and livers. Although this may seem far-fetched, the naturalist Edward Banks recorded in 1949 that the squirrel was "wary, difficult to observe and biting fiercely", and other species of squirrel are known to be active hunters of small vertebrates. The squirrel's reputed carnivorousness has not been observed scientifically but it is known to have a highly specialised diet that includes the nuts of the

canarium ''Canarium'' is a genus of about 100 species of tropical and subtropical trees, in the family Burseraceae. They grow naturally across tropical Africa, south and southeast Asia, Indochina, Malesia, Australia and western Pacific Islands; inclu ...

tree. Other elements of its diet include fruits, seeds and insects.

Research

''Rheithrosciurus'' was the subject of a paper published in the scientific journal '' Taprobanica'' in June 2014. Very little is known about the biology and lifestyle of the squirrel, but in 2015 researchers working in the

Gunung Palung National Park Mount Palung National Park ( id, Taman Nasional Gunung Palung) lies on the island of Borneo, in the Indonesian province of West Kalimantan, north of Ketapang and east of Sukadana. History Mount Palung was first protected in 1937 as a forest nat ...

in the West Kalimantan region of Borneo managed for the first time to obtain clear video pictures of the animal using motion-activated cameras. They were able to record it foraging on the forest floor.

References

External links

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{{Taxonbar, from=Q893959 Mammals described in 1857 Mammals of Borneo Rodents of Indonesia Rodents of Malaysia Tree squirrels Taxa named by John Edward Gray Taxonomy articles created by Polbot