The Bornean Mountain Ground Squirrel Sundasciurus everetti is endemic to Borneo and is found in northern or central-northern areas. It can be found on Mt. Tambuyukon and Mt. Kinabalu in Borneo (Camacho-Sanchez et al., 2019). (Camacho-Sanchez, et al., 2019)
Populations of Bornean Mountain Ground Squirrel Sundasciurus everetti are considered to have high abundance and evenness at 2,000 m and above. (Camacho-Sanchez et al., 2019). It is likely that these species are so isolated to these two mountains because of their preference for high elevation, and the lack of other nearby mountain peaks that reach 2,000 m or above. (Camacho-Sanchez et al., 2019). Most commonly found 915 – 1829 m (3000 – 6000 ft) in elevation, though can occur up to 3353 m (11,000 ft) (Moore and Tate, 1965). This span of elevation allows for Sundasciurus everetti to occupy four distinct vegetation zones: lowland (>1200 m), lower montane (1,200-2,000 m), upper montane (2,000-2,800 m), and subalpine (2,800-3,400 m) (Camacho-Sanchez et al., 2019). (Camacho-Sanchez, et al., 2019; Moore and Tate, 1965)
The Bornean Mountain Ground Squirrel Sundasciurus everetti is a plain grey/brown small mammal with a relatively short bushy tail compared to other Sundasciurus squirrel species, and a relatively long snout (Hawkins et al., 2016). Its underside and chin are a grey/beige color. It has short rounded ears, and a tail that while long like most squirrels, is short in comparison to the other squirrels within its genus. Though its head is small, its muzzle is long and narrow, with small molars. (Moore and Tate, 1965). The tail is black with red tipped hairs (Thorington et al., 2012). The Bornean Mountain Ground squirrel was the smallest animal within the Dremomys genus when it was classified under said genus. It is monotypic, and juveniles and adults can be told apart by a few key features. Adult individuals develop a sagittal crest on their skull, which is a ridge-like bone that runs from the top of the forehead to the crown, bisecting the top surface of the skull lengthwise (Moore and Tate, 1965). Also, individuals are considered juveniles if they still have deciduous third and/or fourth upper premolars (these are the milk teeth) present, or if the sagittal suture on their skull is still partly open. (Moore and Tate, 1965). Another feature that sets the Bornean Mountain Ground Squirrel apart from other related squirrel species is that it gas a “slight flash mark” on its thigh (Moore and Tate, 1965). They also have a single septum in each auditory bullae (Moore and Tate, 1965) (Hawkins, et al., 2016; Moore and Tate, 1965; Thorington, et al., 2012)
No known information on the mating systems of Sundasciurus everetti. Provided instead is the information of a similar species Callosciurus erythraeus. Females will mate 4 - 11 times while in estrus, and males will likewise mate with multiple females - particularly dominant males. For this species, mating occurs throughout the year (Thorington et al., 2012). (Thorington, et al., 2012)
For this species, males have specific calls they perform both before and after mating. The mating begins early in the morning, and lasts for several hours. Males are competitive with once another, with the dominant male earning the opportunity to mate with the female conspecific. Males are also known to "guard" the female they've mated with for ~ 30 minutes after mating is complete. (Thorington, et al., 2012)
No information currently about parental investment for Sundasciurus everetti.
No known information on the lifespan of Sundasciurus everetti specifically, though related squirrels within the genus Callosciurus are recorded as having a maximum lifespan in captivity of 4 years and 6 months (Lim, 2016). (Lim, 2016)
No known information on specific communication habits of Sundasciurus everetti, however, among another species within Sciuridae Callosciurus found in Malaysia, squirrels are know to communicate with predators in a variety of ways, depending on the predator (Tamura and Yong, 1993). Individuals are known to sound off short, repetative barks when in the presence of a terrestrial predator, which alerts nearby conspecifics of the presence of a threat, who then are observed to react by fleeing (Tamura and Yong, 1993). When threatened by raptors, squirrels are known to emit a rattling sound toward the predator itself. When encountering a snake, individuals will call to one another using squeaks and ultimately mob the snake as a means of defense (Tamura and Yong, 1993). It is important to note that these are the behaviors of related tree squirrels within Callosciurus, while our species of focus Sundasciurus everetti, is a ground squirrel. As a result, the specific behaviors may vary between the two species. (Tamura and Yong, 1993)
Sundasciurus everetti are a generalist species that eats predominantly insects, but also eats fruits, nuts, leaves, shoots, and other vegetables. (Moore and Tate, 1965). This data was examined from 26 individuals on Mt. Trus. (Hayssen, 2008). They forage for their food along the ground, as they have a limited capacity for successfully and efficiently climbing trees, though they are capable of doing so (Hayssen, 2008). (Hayssen, 2008; Moore and Tate, 1965)
No known information on predators for species Sundasciurus everetti, however known predators of Malaysian squirrel species Callosciurus include terrestrial carnivores, raptors, and snakes (Tamura and Yong, 1993). (Tamura and Yong, 1993)
As a species that is endemic to Borneo and is in high abundance within its small geographic range, Sundasciurus everetti has an impact on species diversity. The presence of such an abundant, yet isolated, species in a highly volatile region of species fitness contributes to the overall beta diversity between nearby communities (Camacho-Sanchez et al., 2019). This phenomenon is likely due to the biogeography of the region, given that is an island that over geological time has been periodically connected and isolated from the mainland. This back-and-forth has allowed for species to diversify dramatically (Camacho-Sanchez et al., 2019).
Though Sundasciurus everetti is not listed specifically as one of its host species, it is very likely given the sampling location that the flea species Sigmactenus alticola may use Sundasciurus everetti as a host (Wells, Lakim, and Beaucournu, 2011). (Camacho-Sanchez, et al., 2019; Wells, et al., 2011)
No significant economic benefit for the species has been discovered at this time.
Though it is currently listed as least concern, Sundasciurus everetti is potentially susceptible to population decline in response to human disturbance. Being that they are both terrestrial, insectivorous squirrels, as well as a Bornean endemic species, they are considered at higher risk of negative anthropogenic effects compared to other mammal species (Meijard and Sheil, 2008). Because of this, the logging industry may lose potentially profitable land to conservation reserves. However, being that Sundasciurus everetti lives at high elevations, so it is unclear if this is a concern at this time. (Meijaard and Sheil, 2007)
Least Concern and Stable (Thorington et al., 2012) Though at this time the Bornean Mountain Ground Squirrel Sundasciurus everetti seems is not threatened due to its high elevation, it lives within Sundaland which is becoming increasingly threatened by anthropogenic interference (Hawkins et al., 2016). (Hawkins, et al., 2016; Thorington, et al., 2012)
Reclassified in 2015 from Sundasciurus everetti with phylogenetic support:to
Katherine Good (author), University of Washington, Laura Prugh (editor), University of Washington, Tanya Dewey (editor), University of Michigan-Ann Arbor.
uses sound to communicate
having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.
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
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.
an animal that mainly eats leaves.
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
an animal that mainly eats fruit
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
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).
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
found in the oriental region of the world. In other words, India and southeast Asia.
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
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.
breeding takes place throughout the year
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Tamura, N., H. Yong. 1993. Vocalizations in Response to Predators in Three Species of Malaysian Callosciurus (Sciuridae). Journal of Mammology, 74/3: 703-714. Accessed June 06, 2021 at 10.2307/1382292.
Thorington, R., J. Koprowski, M. Steele, J. Whatton. 2012. Squirrels of the World. Baltimore: Johns Hopkins University Press. Accessed May 11, 2021 at https://www.researchgate.net/publication/278301065_Squirrels_of_the_World.
Wells, K., M. Lakim, J. Beaucournu. 2011. Host specificity and niche partitioning in flea-small mammal networks in Bornean rainforests. Medical and Veterinary Entomology, 25/3: 311-319. Accessed June 06, 2021 at 10.1111/j.1365-2915.2010.00940.x.