Ratufa macrouraSri Lankan giant squirrel

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Geographic Range

Ratufa macroura are distributed throughout southern India and Sri Lanka.

Habitat

Ratufa macroura are almost completely arboreal. Forays to the ground occur when evading predators or chasing other squirrels during the breeding season (Nowak 1991). They are very agile in the trees and have the ability to leap more than six meters from tree to tree (Prater 1971). Ratufa macroura use holes in tree trunks as temporary shelters (Nowak 1991).

Physical Description

The smallest of India's giant squirrels, Ratufa macroura have a head and body length of 25-45cm (Finn 1929, Nowak 1991). Their tails can be as long or longer (Nowak 1991). Ratufa macroura possess short round ears that are often tufted. Their hands are very broad and are well adapted for gripping. Both their hands and feet are equipped with large powerful claws, making them agile climbers (Nowak 1991). Ratufa macroura get their common name from the coloration of their tails. The dorsal surface of the tail is gray or brownish-gray with distinct white highlights, giving the fur a grizzled appearance (Prater 1971). The coloration of the rest of the body varies greatly by locality and may include various shades of brown, red, gray and black, but the ventral fur is always lighter (Nowak 1991). A number of subspecies have been classified strictly on the basis of color variations (Ellerman 1961).

  • Range mass
    1.5 to 3 kg
    3.30 to 6.61 lb

Reproduction

Ratufa macroura are poorly studied and there is very little data available on their reproductive cycle. The gestation period is believed to last about 28 days (Nowak 1991). During the breeding season, a large nest, similar in appearance to an eagle's nest, is constructed. Parturition occurs within the nest, and the young remain there for at least two to three months (Joshua and Johnsingh 1994). Each litter consists of one or two young, and the female nurses them from her three pairs of mammary glands (Nowak 1991). It has been speculated that Ratufa macroura may raise several litters each year; however, this is unconfirmed (Nowak 1991).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual

Behavior

Ratufa macroura are most active in the morning and early evening (Joshua and Johnsingh 1994, Prater 1971). Midday is a time of rest, and these squirrels are often observed sleeping spread-eagle on a branch (Prater 1971). The giant squirrels differ from other tree squirrels in that they do not sit upright when feeding. Instead, they balance on their hind feet with their body on one side of the branch and the tail acting as a counterbalance on the other side of the branch (Nowak 1991). Ratufa macroura show limited social behavior. They occur alone or in pairs and are highly territorial (Nowak 1991, Joshua and Johnsingh 1994). These squirrels have a very distinct voice and can be very vocal (Nowak 1991). Like many primates, Ratufa macroura react to the sighting of predators by raising a general alarm, a series of calls and barks that alert others to the predator's presence (Prater 1971). When disturbed, these squirrels may flee or freeze (Joshua and Johnsingh 1994). They have been observed to flatten themselves against a branch and remain motionless when frightened (prater 1971). Overall, Ratufa macroura are very wary and keep themselves well hidden in the dense vegetation (Nowak 1991).

Communication and Perception

Food Habits

Ratufa macroura enjoy a diverse diet that includes fruits, nuts, insects, bird eggs, and the bark of some trees (Nowak 1991). The fruit of the climber Combretum ovalifolium is an especially important food source where it occurs. Young squirrels, upon first emerging from the nest, have been observed to feed exclusively on this fruit (Joshua and Johnsingh 1994).

Economic Importance for Humans: Positive

Like many squirrels, Ratufa macroura probably plays a significant role as an agent of seed dispersal (Gurnell 1987). Also, squirrels worldwide have been hunted for food and their fur (Gurnell 1987). Ratufa macroura is probably not an exception.

Conservation Status

Ratufa macroura are listed on Appendix 2 of CITES (Nowak 1991). The population in south India has been estimated at 300 individuals (Joshua and Johnsingh 1994). The primary threat to their survival is an increasing human population that has caused even traditional activities of forest-dwelling people to become destructive (Joshua and Johnsingh 1994). Thinning of the forest canopy as a result of wood cutting has made Ratufa macroura a more vulnerable target to aerial predators such as the black eagle, Ictinaetus malayensis (Joshua and Johnsingh 1994)

Other Comments

Ratufa macroura is the oldest recorded species in this genus, dating back to 1769 (Ellerman 1961).

Contributors

Ethan Kane (author), University of Michigan-Ann Arbor.

Glossary

bilateral symmetry

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.

chemical

uses smells or other chemicals to communicate

endothermic

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.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

References

Ellerman, J. R. 1961. The Fauna of India. Mammalia. 2d ed. vol. 3. ed. Dr. M. L. Roonwal. Baptist Mission Press, Calcutta

Finn, F. 1929. Sterndale's Mammalia of India. Thacker, Spink & Co., Calcutta.

Gurnell, J. 1987. The Natural History of Squirrels. Facts on File Publications, New York.

Joshua J. and A. J. T. Johnsingh. 1994. Impact of Biotic Disturbances on the Habitat and Population of the Endangered Grizzled Giant Squirrel Ratufa macroura in South India. Biological Conservation, 68: 29-34.

Nowak, R. M. 1991. Walker's Mammals of the World. Fifth Edition. Johns Hopkins University Press, Baltimore.

Prater, S. H. 1971. The Book of Indian Animals. Bombay Natural History Society, Bombay.