Anomalurus derbianusLord Derby's scaly-tailed squirrel

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Geographic Range

Lord Derby's flying squirrel inhabits the tropical and subtropical forests of western and central Africa.

Habitat

The principle habitat is heavy virgin rainforests (Grzimek, 1990) (Nowak, 1991).

Physical Description

Anomalurus derbianus are squirrel-like in form and have a head-body length of 27-37.9 cm. Their tail is approximately 22-28.4 centimeters in length. The upper side of the tail is bushy with a hairy tuft at the end. The fur is silvery-grey on its dorsal side, with the ends of individual hairs brushed in white. The fur on the belly is dense and completely white. These color markings blend well against the background of a tree. Lord Derby's flying squirrels have long whiskers, big pouch-like ears, and large eyes. Their digits are well developed and they have strong claws. Anomalurus derbianus possess a hairy gliding membrane that extends between the forelimbs and the hind limbs and between the hind legs and the tail. This membrane is heavily covered with hair on the top, and sparsely covered on the underside. These scaly-tailed squirrels receive their name from the presence of two rows of overlapping scales on the underside of the tail near the base (Grzimek, 1990) (Nowak, 1991) (Rosevear, 1969).

Reproduction

In West Africa, the main breeding season of A. derbianus seems to be at the end of the rainy season. In East Africa, however, no definite breeding season is apparent. Females, possessing one pair of teats, have two litters of 1-3 young per year; the gestation period is unknown. At birth, babies are large and completely covered with fur. Their eyes are open, and they begin to move around soon after birth. However, the young remain hidden in the nest until almost fully grown. Offspring are fed by the parents, which bring back well chewed up food in their mouths. (Delany, 1975) (Grzimek, 1990) (MacDonald, 1985).

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

Behavior

Anomalurus derbianus are mainly crespuscular and nocturnal. They sleep during the day in nests constructed in the holes of trees. These scaly-tailed squirrels can live alone or in pairs; however, several animals may inhabit the same tree. Lord Derby's flying squirrels leave their retreats soon after sunset, gliding from a high level in one tree to a lower level in another. These "flying" rodents leap into the air with their arms, legs, and tail extended, which stretches their membrane, allowing the animal to glide a surprising distance. They do not actually fly. One incredible glide of A. derbianus was seen to cover 100 meters, and another was reported to have gone 250 meters! When a Lord Derby's flying squirrel alights on a lower tree trunk, it thrusts the scales on the underside of its tail into the bark of the tree, using them as an "antiskidding" device. The scales are also used as an aid in climbing up the rough bark of trees. Anomalurus derbianus do not come to the ground voluntarily. The gliding membrane greatly restricts their terrestrial mobility, and when intentionally placed on the ground, they run away by hopping clumsily, like kangaroos. They also may become quite aggressive, defending themselves with their sharp claws and incisors. (Delany, 1975) (Grzimek, 1990) (Nowak, 1991).

Communication and Perception

Food Habits

Lord Derby's flying squirrels are herbivorous, eating a variety of plant products such as bark, fruit, leaves, flowers, and green nuts. Insects are sometimes included in the diet, but this is most likely by accident (Grzimek, 1990) (MacDonald, 1985).

Conservation Status

Due to the rapid deforestation of their habitat, Lord Derby's flying squirrels are increasingly endangered. No specific protection, however, exists for this species. Any attempts to decrease habitat destruction in Africa will help protect A. derbianus (Grzimek, 1991).

Other Comments

The systematic position of Anomalurus derbianus has been greatly debated. They have been grouped with the porcupines, the mouse-related rodents, and the squirrel-related rodents. They are sometimes included in a separate suborder, Anomaluromorphia, and superfamily, Anomaluroida. Although these animals resemble squirrels in external appearance, parts of their internal anantomy indicate no close relationship to squirrels. The little information known about their predecessors helps to further complicate their phylogenetic classification. The longevity of Lord Derby's flying squirrels is estimated to be several years (Grzimek, 1990) (Nowak, 1991).

Contributors

Rebecca V. Normile (author), University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

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.

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.

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.

sexual

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

tactile

uses touch to communicate

References

Delany, M. 1975. The Rodents of Uganda. Trustees of the British Museums, London.

Grzimek, B. 1988. Grzimek's Encyclopedia of Mammals. McGraw-Hill Publishing Co., NY.

MacDonald, D. 1985. Encyclopedia of Mammals. Facts on File Inc., NY.

Nowak, R. 1991. Walker's Mammals of the World. Johns Hopkins Univ. Press, MD.

Rosevear, D. 1969. The Rodents of West Africa. Trustees of the British Museums, London.