Northern Tree Shrew Tupaia belangeri
Northern Tree Shrews have greyish, olive fur with an elongated snout (Smithsonian National Zoological Park, 2012). The dental formula of the Tupaiidae is incisors 2/3, canines 1/1, pre-molars 3/3, and molars 3/3 (Fuchs and Corbach-Sohle, 2009). Northern tree shrews are moderately sexually dimorphic (Collins and Tsang, 1987; Schehka et al., 2007). Male tree shrews have a larger body size and ring of white hair around the eye compared to females. Males also have a broader skull than the females (Collins and Tsang, 1987). (Collins and Tsang, 1987; Fuchs and Corbach-Sohle, 2009; Schehka, et al., 2007; Smithsonian National Zoological Park, 2012)Fuchs and Corbach-Sohle (2009) describe the difficulty in determining the sex of young tree shrews. As pups the external genitalia of both males and females look alike. Males have a slender and elongate penis, which is posterior to scrotal testes, which can be retracted into the abdominal cavity if the individual is stressed. In females the clitoris is greatly elongated and grooved on its ventral surface. In neonatal shrews the urethra opens together with the vagina as a single opening at the base of the clitoris; this is what looks like the males penis in young female tree shrews. However the clitoris does not have a tubular sheath like the penis. (Fuchs and Corbach-Sohle, 2009) Northern tree shrews have a mass of approximately 50 to 270 grams, Head to Body Length of 12 to 21 cm and a tail length ranging from 14 to 20 cm, usually close to the length of their body (Fuchs and Corbach-Sohle, 2009). Shrew body temperature has been described, ranging from about 35 degrees Celsius to 40 degrees Celsius; this 5 degree difference is much larger than most endothermic animals (Fuchs and Corbach-Sohle, 2009). (Fuchs and Corbach-Sohle, 2009)
50 to 270 g
26 to 41 cm
Northern Tree Shrews have a monogamous mating system (Collins and Tsang, 1987). Introductions between a mating pair are possibly the hardest part of breeding for Northern Tree Shrews. Copulation can occur within a few hours if the female accepts the male (Fuchs and Corbach-Sohle, 2009). However, they usually use more aggressive behaviours. Fuchs and Corbach-Sohle (2009) suggest two explanations: first, that the individuals merely don't like each other, and second that to mate one animal has to enter the others territory. Northern Tree Shrews, male or female, will defend their territory against intruders. If the couple can overcome this they will form a stable breeding pair and continue to breed together. Females have an 8 to 12 day oestrous cycle. Ovulation is thought to be induced by copulation (Martin, 1990) (Collins and Tsang, 1987; Fuchs and Corbach-Sohle, 2009; Martin, 1990)
Under natural and artificial conditions Fuchs and Corbach-Sohle (2009) observed that breeding can occur at any time of the year; no peak periods were found. Males and females become sexually reproductive around the same time. Males will be active between four and five months and females can give birth to their first litter at approximately 4 months old. Northern Tree Shrews have a litter size of 1 to 5 young. The gestation period occurs for approximately 41 to 45 days and females give birth to hairless, altricial young. Pups ears open at around 10 days and their eyes open at approximately 20 days after birth. Female young tend to be heavier than males, but on average young will have a birth mass of 6 to 10 grams (Fuchs and Corbach-Sohle, 2009). Young will drink their motherís milk until they are around 35 days old when they wean off the liquid diet. Northern Tree Shrews reach puberty at about 2 months old and can be separated from their mother at about 50 to 60 days (Fuchs and Corbach-Sohle, 2009). Older mothers may have problems with infertility, still birth, cannibalism or abortion. These problems can also occur in females that are stressed, which is likely in tree shrews as they are highly susceptible to stressors.
Habitat and Ecology:
This widespread species is found in deciduous and evergreen primary forest and secondary forest, commonly in karst and associated natural scrub vegetation, from sea level up to upper montane areas (Molur et al. 2005; W. Duckworth pers. comm.). It is highly adaptable and may be found in oil palm plantations (K. H. Han pers. comm.), coconut plantations (Parr 2003), and regenerating scrub and ruderial mixes above abandoned dry rice fields (W. Duckworth pers. comm.). It has been seen very far from tall forest, and is probably able to live independently of tall forest (such as in far northern Lao PDR; W. Duckworth pers. comm). Immediately after birth the mother will nurse her pups and thereafter only return to feed her young once every 48 hours (Fuchs and Corbach-Sohle, 2009). They receive approximately 5 to 10 millilitres of milk, with a relatively high fat content of about 25%. Pups consume this amount of milk in approximately 2 to 10 minutes. As a result pups have less than 2 hours contact with their mother during the 30 to 35 day period. Martin (1990) described that as the lowest mother to infant contact and smallest parental investment for viviparous mammals described thus far. Males are not involved in parental care after copulation (Fuchs and Corbach-Sohle (2009). (Fuchs and Corbach-Sohle, 2009. Typically northern tree shrews live in monogamous pairs (Smithsonian National Zoological Park, 2012). One adult male and female share overlapping territories. Males and females will both defend their territories against conspecifics year round. Territorial fights are documented between adults of the same sex (Fuchs and Corbach-Sohle, 2009). Tree shrews use scent marking, excreted from a gland on their chest, to mark their territories (Fuchs and Corbach-Sohle, 2009). The young tree shrews leave the nest around the onset of puberty and they become completely self-sufficient (Collins and Tsang, 1987). (Collins and Tsang, 1987; Fuchs and Corbach-Sohle, 2009; Smithsonian National Zoological Park, 2012) Northern tree shrews have relatively stable home ranges of about 2 acres or 0.81 hectares (Smithsonian National Zoological Park, 2012). (Smithsonian National Zoological Park, 2012) Northern tree shrews make 8 distinct sounds (Fuchs and Corbach-Sohle, 2009). Of these 4 can be associated with functional categories that are described by Binz and Zimmermann (1989): alarm, attention, contact, and defence. Tree shrew noises can range from 0.4 to 20 kHz. The structure of the sounds depends on the status and motivation of the individuals; their pitch increases with fear and decreases in pitch (or increases in frequency) with increased aggression (Kirchhof et al., 2001). Kirchhof et al. (2001) also note that tree shrews do not use ultrasonic localisations. Tree shrews use scent marking to indicate boundaries of their territories (Fuchs and Corbach-Sohle, 2009). (Binz and Zimmermann, 1989; Fuchs and Corbach-Sohle, 2009; Kirchhof, et al., 2001. It has been noted that tree shrews will react to predation risk (Schehka et al., 2007; Fuchs and Corbach-Sohle, 2009). They will display defensively to a threat, specifically baring teeth and making high pitched, loud vocalizations (Schehka, 2007). Specific predators of northern tree shrews are not specified. However, due to their size and behaviour possible predators could include large birds of prey, snakes, and potentially some carnivorous mammals. While the main food source of northern tree shrews is insects, they also eat fruit to supplement their diet. It could be inferred that they play a role in the seed dispersal of fruit bearing trees
Found in South-East Asia, North of the isthmus of Kra, including: Thailand, Bangladesh, Burma, far North-Eastern India and Nepal, Southern China, Cambodia, Lao PDR, Vietnam, and associated coastal islands, including Hainan. It probably also occurs on Preparis Island north of the Andaman Islands (Helgen 2005). Listed as present in Bhutan by Molur et al. (2005). Recorded to 3,000 m in China (E. Smith pers. comm).
Bangladesh; Bhutan; Cambodia; China; India; Lao People's Democratic Republic; Malaysia; Myanmar; Thailand; Vietnam
There are no major known threats to this species.
It is found in numerous protected areas throughout its range, such as Kang Kachan National Park (Thailand) and Mehao Wildlife Sanctuary, Namdapha National Park, and Singhalila National Park (India). It is listed on CITES Appendix II.