About Ratufa bicolor (Sparrman, 1778)
The black giant squirrel (Ratufa bicolor) is one of the largest squirrel species in the world. On average, adult individuals weigh 1.05–1.25 kg (2.3–2.8 lb), have a head-and-body length of 34–37 cm (13–15 in), and a tail 41–42 cm (16–17 in) long. The subspecies R. b. condorensis native to Côn Sơn Island, Vietnam, averages around 30 cm (12 in) in head-and-body length and 32 cm (13 in) in tail length, but otherwise matches the appearance of the typical subspecies. This species is characteristically distinctly bicolored, with dark upperparts and pale underparts. Its back, the top of the head, ears, and bushy tail range from deep brown to black, while its underparts are light buff-colored. In Sumatra, Java, and Bali, the hairs on the back and tail have light-colored tips, which makes these regions appear relatively pale; however, the upperparts, especially the thighs and shoulders, still remain distinctly darker than the underparts. On small islands off Myanmar and in the Strait of Malacca, the black giant squirrel has underparts colored orange to reddish-yellow. All habitats within Ratufa bicolor's range are forested, and the species occurs across a variety of bioregions. Its elevation range extends from sea level up to at least 2,500 m (8,200 ft). Over recent decades, R. bicolor's habitat has faced consistent encroachment from human settlement, timber harvesting, and agriculture. Combined with overhunting by humans across parts of its range, this has caused a total population loss of up to 30% over the past ten years. In some regions, the species is protected from hunting by law or local tradition. In South Asia, R. bicolor lives in tropical and subtropical coniferous and broadleaf forests. In Southeast Asia, it inhabits tropical broadleaf evergreen and semi-evergreen forests, and is rarely found in coniferous forests. In the tropical rainforests of the Malay Peninsula and Indonesia, R. bicolor is less abundant than it is in other parts of its range. This is likely because other arboreal species, especially primates, compete with it for food in the upper forest canopy. Good locations to spot the black giant squirrel include Kaziranga National Park in Assam, India, and multiple populations occur in the lower elevation areas of Neora Valley National Park, Kalimpong, India. A recent study conducted in India found that precipitation in the wettest month of the year is one of the major factors influencing R. bicolor's habitat preference, along with land use and vegetation. The species can be found well above 1400 meters in multiple locations across India; more than 20% of its presence records in the country are from elevations above 1500 meters, reaching as high as 2700 meters. Study predictions indicate that by 2050, climate change could cause the species to lose more than 97% of its current suitable habitat in India.
