Common Tree shrew (Tupaia glis)
The Common Tree Shrew is one of the largest among tree shrews. Average body length is between 16–21 cm (6.3–8.3 in), and average weight is around 190g, with varying colours of reddish brown, greyish or black upper parts and whitish belly. Its long bushy tail is dark greyish brown and almost reaches the length of the body. The paws are bare with sharp nails, and there is a naked patch of skin above its long nose. Both sexes are similar. The measurements of the Tupaia glis according to 21 specimens are head- to-body length: 170mm to 235mm, tail length: 170mm to 242mm and hind foot: 45mm to 56mm. The common tree shrew usually has a pale stripe on each shoulder.
There are two subspecies T.g. longipes and T.g. salatana, with T.g. longipes being duller in coloration than T.g. salatana. The under parts of longipes are dull buff to reddish buff, and the underside of the tail is greyish. The under parts and underside of the tail are dark reddish in salatana. Similar species are Tupaia splendidula and Tupaia montana.
Distribution and habitat
Common Tree Shrews occur south of about 10° N latitude in Southern Thailand through mainland Malaysia and adjacent coastal islands to Singapore. In Indonesia, they are found on the islands of Siberut, Batu, Sumatra, Java, Bangka, Riau, Lingga and Anambas.Usually they are found in primary dipterocarp forest, but are tolerant to some degree of habitat modification. They have also been recorded from secondary forest, plantations, fruit orchards and trees near housing areas.
This species is probably present throughout the lowlands and hills up to 1,100 m (3,600 ft) in the Kelabit Highlands of Borneo. The subspecies T.g. longipes occurs in the north of Borneo, in Sarawak, and in East Kalimantan including Sabah. The subspecies T.g. salatana occurs in the south of Rajang River and Kayan River in Borneo.
Common Tree Shrews inhabit protected areas, including Pasoh Forest Reserve on the Malay Peninsula and Krau Wildlife Reserve.
Ecology and behaviour
Common Tree Shrews are active during the day, and forage for food alone or in pairs, mainly on the ground, among shrubs and tree holes. They feed on fruits, seeds, leaves, and insects especially ants and spiders. They are also reported to catch lizards.
They are very agile in climbing both large vertical tree trunks and bushes, and occasionally jump from stems of a young tree to that of another as much as 60 cm (24 in) away. Their climbing is concentrated in lower heights. They frequently scent-mark their territories by chest and ano-genital rubbing with a secretion from glands on chest and scrotum. Adult males are more secretory than females and juveniles. In the Bukit Timah Nature Reserve, mean home ranges of adult males were estimated at 10,174 m2 (109,510 sq ft), of adult females at 8,809 m2 (94,820 sq ft), of juvenile males at 7,527 m2 (81,020 sq ft), and of juvenile females at 7,255 m2 (78,090 sq ft), with partial overlaps between male and female ranges varying from 0.4% to 56.8%. Home ranges of adult residents of the same sex overlap to a lesser degree than those of opposite sexes. A male’s range may include the ranges of two or three females. A high overlap between ranges of one adult male and one adult female indicates that they form a stable pair. Juvenile ranges of either sex adjoin or overlap with ranges of adults, suggesting that the juveniles are family members. Individuals of the same sex are involved in aggressive territorial chases.
Juvenile males depart from their family's territory sooner than juvenile females.
Both sexes of Common Tree Shrews are sexually mature at the age of about 3 months. In captivity, females give birth for the first time at the age of about 4.5 months, usually in February. A postpartum oestrus results in more births in April. Their oestrus cycle is 8 to 39 days, and the gestation period lasts 40 to 52 days, after which a litter of one to three individuals is born. The new born offspring weighs about 10 to 12 grams. Females suckle their young every other day, and neglect their young as long as possible. They won’t even be able to identify their own young if they didn’t mark them with the scent produced from glands in their sternum and abdomen. Juveniles leave the nest between 25 to 35 days of age. Longevity of a captive common tree shrew has been recorded as 12 years and 5 months.
From October to December, Common Tree Shrews are reproductively inactive. The mating season starts at the onset of the monsoon season in December and lasts until February. Oestrus and pre-oestrus behaviour is characterized by adult males pursuing adult females. Males emit chattering, and appear to be extremely excited. They also chase each other and fight. Females do not actively choose a partner among the male participants of chases. The dominant male gains access to females.
In tropical rainforest habitats in West Malaysia, density of Common Tree Shrews varies from about two to five animals per hectare. Their annual breeding coincides with the abundance of invertebrates after the dry season. Their main reproductive period is between February and June, and their litter size invariably two. Some females breed more than once a season, and the age at first pregnancy is seven months. The main period of emigration or mortality of young is during the breeding period or monsoon.
Common Tree Shrews are threatened due to deforestation and ensuing human activities in agriculture, plantation and commercial logging. Moreover, other pressures such as hunting for food and sport can create pressure to the species.
Tupaia glis are being used by researchers as animal models for human diseases because of their close relationship to primates, and their well-developed senses of vision and hearing. Research studies have included hepatitis.