The specific communication systems of black giant squirrels have not been studied thoroughly. However, they likely communicate in much the same way as other members of the squirrel family. This means that they communicate through a series of vocal chirps and barks. In other Malaysian squirrel species, communication plays a large role in mating systems. Males locate and attract females using ultrasonic sounds. They will also bark post copulation for several minutes (Tamura, 1993). When courting, both genders will scent mark using urination to attract members of the opposite sex and show availability (Paulraj, 1988). As with many squirrels, they use alarm calls when they see a predator (Thorington and Ferrell, 2006).
Communication Channels: acoustic ; chemical
Other Communication Modes: scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Black giant squirrels are susceptible to hunting and deforestation. they are in decline mainly due to over-hunting and secondarily due to habitat loss (Timmins and Duckworth, 2008). Historically, they have been sold in fresh food markets in Loas ("Wildlife in Lao PDR: 1999 Status Report", 1999). Black giant squirrels are significantly less abundant or not present in logged forests and plantation areas. This reduction in number is strongly correlated to the reduction in canopy cover and tree density (Datta and Goyal, 2008), because black giant squirrels nest in the high canopy layer of tall trees (Harrison and Traub, 1950).
CITES: appendix ii
Black giant squirrels have been known to steal fruit from local orchards. (Harrison and Traub, 1950)
Negative Impacts: crop pest
Black giant squirrels were, until recently sold in large quantities at fresh food markets in Vientiane, Loas. At the time, they were one of the most commonly found specimens in several markets. In recent years, they are not as abundant in these markets due to declining wild populations ("Wildlife in Lao PDR: 1999 Status Report", 1999).
Positive Impacts: food
Because of their affinity for fruit and nuts black giant squirrels disperse seeds of large-seeded tree species. More specifically, these squirrels are known to disperse Burseraceae seeds (Canarium euphyllum; Kitamura et al., 2006).
Ecosystem Impact: disperses seeds
Mutualist Species:
Like most squirrels, black giant squirrels eat fruits and nuts. Little is known about their foraging activity and the amount of food they consumes (Meijaard and Sheil, 2006). Locals within its range insist that they frequent their orchards (Harrison and Traub, 1950).
Plant Foods: seeds, grains, and nuts; fruit
Primary Diet: herbivore (Frugivore , Granivore )
Black giant squirrels are found across much of the Oriental region. Their native range spans from northern Nepal and southern China through Vietnam. They are also numerous across the Malaysian Peninsula (Endo et al., 2004). For this reason they are also referred to as Malayan giant squirrels.
Biogeographic Regions: oriental (Native )
Black giant squirrels are only found in heavily forested areas. Their range spans from sea level to as high as 2000 m. Since they are highly susceptible to deforestation, they are rarely found in degraded areas ("Wildlife in Lao PDR: 1999 Status Report", 1999). These squirrels are commonly seen between elevations of 1900 m and 2000 m, most frequently in areas rich in Vietnamese white pine, Pinus dalatensis (Abramov, Rozhnov and Morozov, 2006). Often, they are found nesting in the canopy of tall trees (Harrison and Traub, 1950).
Range elevation: 0 to 2000 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: forest
The average lifespan for black giant squirrels is 18 years in captivity. There are very few records detailing the lifespan of black giant squirrels all of which have been collected from captive, wild-born specimens.
Range lifespan
Status: captivity: 19 (high) years.
Average lifespan
Status: captivity: 18 years.
Black giant squirrels are characterized by their distinct size and pelage. With masses of 1546 g and lengths of 798 mm (head to tail), black giant squirrels are one of the largest members of the squirrel family (Thorington and Heaney, 1981). They are identifiable by their black fur, tan chest patch and occasionally tan tail tip. As is the case with most tree squirrels they do not exhibit sexually dimorphic. Unlike many squirrels, black giant squirrels do not have a tail that curls over its back. Instead, their tail lays limp behind them (Dobroruka, 1975).
Average mass: 1546 g.
Average length: 798 mm.
Sexual Dimorphism: sexes alike
Other Physical Features: endothermic ; bilateral symmetry
Black giant squirrels are preyed upon by several species. They live in the upper canopy, which allows them to avoid many ground predators (Harrison and Traub, 1950). However, this puts them at risk of predation from birds of prey such as Wallace's hawk eagle, which preys on arboreal mammals in Southeast Asia (Haring et al., 2007). Black giant squirrels are also at risk of predation by snakes when in the canopy. In order to collect food on the forest floor, they will occasionally move down from the canopy (Meijaard and Sheil, 2008); during which they are at risk of predation from terrestrial carnivores. However, the specific species that eat black giant squirrels have not been thoroughly studied.
Black giant squirrels have several means of predator avoidance. As mentioned before, the location that they live in is out of reach of many terrestrial predators (Harrison and Traub, 1950). Also, as with many squirrels, they will use alarm calls when they see a predator. Their fur also provides camouflage, similar to many other squirrels. The ventral, or belly is a light color, while the dorsal, or back remains dark. This helps them blend in with the changing light patterns of the forest layers and avoid being seen from both terrestrial and aerial predators (Thorington and Ferrell, 2006).
Known Predators:
Anti-predator Adaptations: aposematic ; cryptic
Mating behavior of black giant squirrels have only been studied with a few select captive pairs. However, several commonalities have been witnessed. Courtship behaviors include scent marking, chasing, nest building and grooming. Scent marking involves both male and females pressing their anogenital region against an object or the ground and urinating while moving slowly forward (Paulraj, 1988). Chasing involves males pursuing the female while she runs and hides. Often, this gives less dominant males a chance to find her before they can be chased off by older males (Thorington and Ferrell, 2006).
The mating systems for black giant squirrels in the wild have not been well studied. However, like many other solitary tree squirrels it is known to be polygynandrous (Dobroruka, 1975). Similar Malaysian tree squirrels are also polygynandrous. Their mating systems are assumed to reflect those of close relatives, Indian giant squirrels. For other close relatives, plantain and gray-bellied squirrels, when a female comes into estrous, six to eight males will come to the area early in the morning. During a several hour mating bout, five to seven males will copulate with the female. Males frequently attempt to chase off other males when in close proximity to the female (Tamura, 1993). Since several males will copulate with the female, it is not uncommon for siblings of the same litter to have different paternity (Thorington and Heaney, 1981). Squirrels that inhabit similar ecological or energetic niches also have similar mating and reproductive systems (Hayssen, 2008).
Mating System: polygynandrous (promiscuous)
Black giant squirrels exhibit very similar reproductive behavior to most tree squirrel species. A female will give birth to one to two altricial young twice yearly. They have a gestation period that lasts an average of 31.5 days. After which, they will nurse their young for approximately five weeks. Like all members of the squirrel family, black giant squirrels reproduce sexually with the male impregnating the female during internal copulation. The reproductive efforts of all tree squirrel species take place in the canopy layer. This includes both nesting and mating efforts (Hayssen, 2008). Black giant squirrels give birth in two periods, from April to May and August to September (Hayssen, Tienhoven, and Tienhoven, 1993).
Breeding interval: Giant black squirrels breed twice yearly.
Breeding season: Mating occurs from March to April or July to August.
Range number of offspring: 1 to 2.
Average number of offspring: 1.44.
Range gestation period: 28 to 35 days.
Average weaning age: 5 weeks.
Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Black giant squirrels give birth to altricial young that must be nursed; mothers provide this in the form of lactation. Males are only present for insemination and do not aid in parental care (Harrison and Traub, 1950). No evidence suggests that the young remain with the mother after they are weaned.
Parental Investment: altricial ; female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
The black giant squirrel or Malayan giant squirrel (Ratufa bicolor) is a large tree squirrel in the genus Ratufa native to the Indomalayan zootope. It is found in forests from northern Bangladesh, northeast India, eastern Nepal, Bhutan, southern China, Myanmar, Laos, Thailand, Malaysia, Cambodia, Vietnam, and western Indonesia (Java, Sumatra, Bali and nearby small islands).[1]
The black giant squirrel is one of the largest species of squirrel in the world. On average, an adult black giant squirrel weighs around 1.05–1.25 kg (2.3–2.8 lb), has a head–and–body length of 34–37 cm (13–15 in), and the tail is 41–42 cm (16–17 in) long. The subspecies R. b. condorensis of Vietnam's Côn Sơn Island averages only c. 30 cm (12 in) in head–and–body length and the tail 32 cm (13 in), but otherwise it resembles the typical subspecies.[4]
This species is typically distinctly bicoloured with dark upperparts and pale underparts. The back, top of the head, ears and bushy tail are deep brown to black and the underparts are light buff-coloured. In Sumatra, Java and Bali the hairs of the back and tail are light-tipped, making these sections appear relatively pale (however, the back is still distinctly darker than the underparts). On small islands off Myanmar and in the Strait of Malacca the black giant squirrel has reddish-yellowish underparts.[4]
Ratufa bicolor's range includes a variety of bioregions that all share the commonality of being forested. It ranges in elevation from sea level up to at least 1,400 metres (4,600 ft), in some of the most rugged land in the world. However, in recent decades, R. bicolor's habitat has been steadily encroached upon by human settlement, timber harvesting and agriculture, which along with overhunting by human predation in parts of its range, has resulted in a total loss of up to 30% of the population in the past ten years.[1] However, in some places this species is protected from hunting by law or tradition.[1]
In South Asia R. bicolor dwells among tropical and subtropical coniferous and broadleaf forests.[1]
In Southeast Asia R. bicolor lives in tropical broadleaf evergreen and semi-evergreen forests, but is rarely seen in coniferous forests.[1]
In the tropical rainforest of the Malay Peninsula and Indonesia, R. bicolor is not as abundant as elsewhere in its range, which is probably due to competition from other arboreal species (especially primates) for food in the upper forest canopy.[1]
Among the better places to sight the black giant squirrel is the Kaziranga National Park in the state of Assam, India.[5] Several populations are present in the lower range of the Neora Valley National Park, Kalimpong, India.
A recent study from India showed precipitation during the wettest month of a year is one of the major contributing factor for habitat preference of R. bicolor, along with land use, and vegetation. The species also may be found way beyond 1400 meters in several places. More than 20% of the presence records of the species has been observed above 1500 meters and up to 2700 meters in India. It has been predicted through study that by the year 2050, this species may loose more than 97% of its present suitable habitat due to climate change in India.[6]
R. bicolor is diurnal and arboreal, but sometimes climbs down from the forest canopy to feed on the ground.[1] The black giant squirrel rarely enters plantations or settlements, preferring the wild forest.[1]
Its diet consists of seeds, pine cones, fruits, and leaves.[1] It is primarily solitary, and has a litter of from 1 to 2 young, which it raises in a drey (or nest), often located within a hollow space of a tree.[1]
Further study is required to determine whether Ratufa bicolor actually represents several similar species.[1]
The table below lists the ten recognized subspecies of Ratufa bicolor, along with any synonyms associated with each subspecies:[3]
From Kaeng Krachan National Park, Thailand
{{cite book}}: CS1 maint: multiple names: authors list (link) The black giant squirrel or Malayan giant squirrel (Ratufa bicolor) is a large tree squirrel in the genus Ratufa native to the Indomalayan zootope. It is found in forests from northern Bangladesh, northeast India, eastern Nepal, Bhutan, southern China, Myanmar, Laos, Thailand, Malaysia, Cambodia, Vietnam, and western Indonesia (Java, Sumatra, Bali and nearby small islands).
