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Idiurus zenkeripygmy scaly-tailed flying squirrel

By Mandie Cyr

Geographic Range

Idiurus zenkeri is found throughout Upper Cameroon to Rio Muni and Northwest Gabon. The range extends from the northeast and east portion of Zaire, east of the Lualaga to Lake Kivu, eastern Nigeria, the Gold Coast, Gabon, Liberia, and west Uganda. (Booth, 1958; Haltenorth and Diller, 1977)

Pygmy scaly-tailed flying squirrels are found in the following countries: Cameroon, Central African Republic, Congo, the Democratic Republic of the Equatorial Guinea, and Uganda. (Jones, 1971; Kingdon, 1974; Thorington, 2003)

Habitat

Pygmy scaly-tailed flying squirrels are found in moist tropical and subtropical climates. They are arboreal, occurring mainly in forests composed of the following tree taxa: Klainedoxa species, Pseudoprosopis species, Paramacrolobium species, Gilbertiodendron species, and Pentaclethra species. (Jones, 1971; Kingdon, 1974; Thorington, 2003)

  • Range elevation
    Primarily high forests (high) m
    ft

Physical Description

Pygmy scaly-tailed flying squirrels have a body length from 63 to 75 mm, tail length of 83 to 104 mm, hind foot length of 14 to 17 mm, ear length of 11 to 15 mm, and greatest length of skull of 22 mm. They are the smallest of the scaly-tailed squirrels. They have a feathery tail. Dorsal fur color is grey to brown and ventral fur color is whitish. A gliding membrane is located between the fore and hind limbs. Scaly-tailed squirrels have silky fur, long whiskers, and two rows of pine cone like scales on the underside of their tails. The top of the tail is covered with sparse, 2 cm long hairs. The tail has a row of short (2 to 3 mm), stiff hairs along both sides. The entire underside of the tail is hairless, with a 1.5 to 2.5 cm long rough, scaly patch that extends from the tail base. These scales typically act as anti-skid devices that also provide extra grip while climbing or support when resting. Sharp claws also provide extra grip. The fur is fine, although less dense on the gliding membrane. The elbow has a cartilaginous extension that allows for greater freedom of movement in the upper limbs. (Barnet, 2006; Haltenorth and Diller, 1977; Kingdon, 1974; Thorington, 2003)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    17.4 g
    0.61 oz
  • Range length
    63 to 75 mm
    2.48 to 2.95 in

Reproduction

The mating system of Idiurus zenkeri is not reported. (Jones, 1971)

There is little information on reproduction in Idiurus zenkeri. It is believed to be similar to Idiurus macrotis and other anomalurids. Young are precocial and born in litters of up to three young. Parents will finely chew food in their cheeks and then pass it on to their young during the weaning process. No pregnant females have been observed. It is thought that females may give birth to their young away from the colony. (Barnet, 2006; Booth, 1958; Kingdon, 1974; Thorington, 2003)

  • Breeding interval
    Breeding intervals are not known.
  • Breeding season
    The breeding season of I. zenkeri is not reported.
  • Range number of offspring
    3 (high)

Like all mammals, females I. zenkeri nurse and care for their young until they are weaned. Otherwise, little is known about the investment of male and female parents and length of dependence.

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female

Lifespan/Longevity

There is no information known about the longevity of I. zenkeri.

Behavior

Pygmy scaly-tailed flying squirrels are nocturnal, gregarious species that rest in tree hollows or behind peeling bark with other flying squirrels in groups of up to 100 individuals consisting of both sexes and all ages. They climb with agility on smooth tree trunks and jump or glide between tree branches. They can glide up to 3 meters between trees without losing height. ("Flying Mouse", 2006; Barnet, 2006; Corbin and Cordeiro, 2006; Haltenorth and Diller, 1977; Kingdon, 1974; Thorington, 2003)

Home Range

Home range size of I. zenkeri is not reported. (Jones, 1971)

Communication and Perception

Pygmy scaly-tailed flying squirrels emit a mouse-like squeak that is heard when individuals are disturbed. Communication by scent is important in anomularids. Large groin glands produce strong smelling secretions. (Barnet, 2006; Haltenorth and Diller, 1977)

Pygmy scaly-tailed flying squirrels have large, forward facing eyes that provide excellent binocular vision and relatively large ears that support acute hearing that could include ultrasonic frequencies.

Food Habits

Pygmy scaly-tailed flying squirrels are capable of traveling several kilometers in search of food. Foraging behaviors are probably similar to that of Idiurus macrotis. Pygmy scaly-tailed flying squirrels eat fruit, nuts, tree gums, and bark, including oil palm fruits. Anomalurids have relatively long digestive tracts, which allows for the maximum absorption of nutrients. (Barnet, 2006; Haltenorth and Diller, 1977; Thorington, 2003)

  • Plant Foods
  • wood, bark, or stems
  • seeds, grains, and nuts
  • fruit
  • sap or other plant fluids

Predation

There is little information on predators of pygmy scaly-tailed flying squirrels. Eagles have been known to prey on other scaly-tailed squirrel species and it is likely that birds of prey and arboreal snakes prey on scaly-tailed squirrels. (Barnet, 2006; Thorington, 2003)

Ecosystem Roles

Anomularids will chew off the tops of young, non-food tree species, resulting in a reduction of competition for their favored trees species and a change in the composition of forest trees. Pygmy scaly-tailed flying squirrels may also contribute to the dispersal of forest tree seeds when they eat fruit. (Barnet, 2006)

In 1968, four individuals of I. zenkeri were found nesting in a tree on Dipikar Island with two individuals of Anomalurus derbianus. (Jones, 1971)

Mutualist Species

Economic Importance for Humans: Positive

Pygmy scaly-tailed flying squirrels are important members of their native ecosystems.

Economic Importance for Humans: Negative

Scaly-tailed squirrel species will occasionally steal oil palm nuts, but they are not generally considered pest species. (Barnet, 2006)

Conservation Status

In 1996, I. zenkeri was listed as lower risk/near threatened by the IUCN. This species is poorly known and has since been re-categorized as data deficient. Idiurus zenkeri populations are negatively impacted by timber harvesting and destruction of habitat for agriculture. (Jones, 1971; Thorington, 2003)

In order for informed conservation planning, information regarding a number of life history characteristics is required, including: population numbers, distribution, ecological interactions, and reproductive characters.

Other Comments

Studying anomularid species in the field is difficult, not only because they are nocturnal, but also because they are sensitive to the red lights that biologists use at night. Anomularids are not rare; they are only very difficult to study and observe.

Idiurus zenkeri and feather-tailed gliders (Acrobates pygmaeus) are a remarkable example of convergence. (Barnet, 2006; Jones, 1971; Kingdon, 1974)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Mandie Cyr (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.

Glossary

Ethiopian

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

World Map

acoustic

uses sound to communicate

arboreal

Referring to an animal that lives in trees; tree-climbing.

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

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

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.

fertilization

union of egg and spermatozoan

forest

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

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

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.

nocturnal

active during the night

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.

sedentary

remains in the same area

sexual

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

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

ultrasound

uses sound above the range of human hearing for either navigation or communication or both

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

2006. "Flying Mouse" (On-line). Accessed October 10, 2006 at http://en.wikipedia.org/wiki/Flying_mouse.

Barnet, A. 2006. "Scaly-tailed squirrels" (On-line). Accessed October 10, 2006 at http://www.answers.com/topic/scaly-tailed-squirrels-anomaluridae-biological-family.

Booth, A. 1958. The Niger, the Volta and the Dahoney Gap as Geographic Barriers. Evolution, 12/1: 48-62.

Corbin, C., N. Cordeiro. 2006. Gliding characteristics of Lord Derby's Anomalure (Anomalurus derbianus) in Tanzania. African Journal of Ecology, 44: 106-108.

Haltenorth, T., H. Diller. 1977. The Collins Field Guide to the Mammals of Africa including Madagascar. Massachusetts: The Stephen Green Press.

Jones, C. 1971. Notes on the Anomalurids of Rio Muni and Adjacent Areas. Journal of Mammalogy, 52/3: 568-572.

Kingdon, J. 1974. East African Mammals. London: Academic Press.

Thorington, R. 2003. Idiurus zenkeri.

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