Derby's woolly opossum
|Derby's woolly opossum|
|Derby's woolly opossum range|
C. derbianus weighs between 200 and 400 grams (7.1 and 14.1 oz). The length of the head and body is between 180-290 mm and tail length adds 270-490 mm. Its fur is very woolly in texture and tends to be fine.  Coloration varies geographically but the animal often possesses a dark strip running from the top of the head to the nose.  The face varies from a light creamy white or buffy color and the back is red-brown. The belly is a yellowish-white.  Some individuals have a gray patch between the shoulders, but this varies geographically. Juveniles may appear more gray then adults.  The digits are clawed with the exception of the opposable thumb. The prehensile tail is longer than the head and body, making up two thirds of the animal's total length. The distal half of the tail is naked, and is an identifying feature. Other species in the area possess tails with fur covering more of the tail.  C. derbianus females develop a brood pouch on their undersides while carrying young. [3, 4] Once offspring leave the pouch, it shrinks into small skin folds.  One study identified 37 caudal vertebrae, however that may vary between individuals.  The skull can be identified by very large zygomatic arches. 
C. derbianus is primarily arboreal, living in tree hollows or on branches. It lives in highland and lowland rainforests, typically are nearby a stream or other source of water. It is found at altitudes up to 2,600 m (8,500 ft).
C. derbianus is omnivorous, feeding on a variety of food sources including fruits, nectar, invertebrates, leaves, seeds, and small vertebrates such as mice. [4, 5, 6] The animal hunts nocturnally and is a valuable pollinator for species such as Marcgravia nepenthiodes, a flowering plant. 
C. derbianus could be locally threatened by deforestation, but is considered common throughout its range.  Populations are sustained due to a lack of prominent predators and broad habitat tolerance.  In the past, C. derbianus has trapped for its fur, however there is no longer a demand for the skins. 
Reproduction and Life Cycle
C. derbianus reaches sexual maturity at seven to nine months. They are estrous, with cycles lasting approximately 27-29 days.  Mating season is not well known. A Nicaraguan study found mating season to be year round, while other studies determined that mating season continues throughout the dry season (January to July). After birth, the young are kept in the mother’s pouch attached to a teat until they reach a level of maturity similar to that of a placental animal at birth.  Sexual maturity is reached at seven to nine months.  Average litter size is 3-4, however some may be as large as 6.  C. derbianus has been found to survive up to 5 years in captivity, and most likely has a shorter life span in the wild.
C. derbianus is a solitary animal and has a small home range consisting of a few close trees.  Males are usually more active than females, and peak activity for both tends to be within a few hours of either the beginning or end of a day.  This species moves in a trot-like gait, often using its tail for both balance and as a gripping mechanism.  The tail may also be used to carry items such as plant material for nests.  A defensive stance, involving both hind legs and one foreleg on the ground with the second foreleg raised, may be assumed if a threat is perceived.  If very threatened, the animal may leap towards the offender and bite at it, although it prefers to retreat. 
This species sleeps in a ball with its tail wrapped around its body 
Etymology of Name
This species got its name (Derby’s Woolly Opossum or Central American Woolly Opossum) due to its location and the texture of its fur. 
- Lew, D., Soriano, P., Cuarón, A. D., Emmons, L., Reid, F. & Helgen, K. (2008). Caluromys derbianus. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 28 December 2008. Database entry includes justification for why this species is of least concern
- Gardner, A. L. (2005). "Order Didelphimorphia". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. p. 3. ISBN 978-0-8018-8221-0. OCLC 62265494.
- Gardner, Alfred L. (2007), "Caluromys derbianus", in Gardner, Alfred L., Mammals of South America, Volume 1: Marsupials, Xenarthrans, Shrews, and Bats, Chicago: University of Chicago Press, pp. 39–116 (p. 100), ISBN 978-0-226-28240-4
4. Nowak, R. "Marsupialla." Walker's Mammals of the World. 5th ed. Baltimore, MD: Johns Hopkins Univ. Pr., 1991. 23-25. Print.
5. "Caluromys Derbianus." Mammalian Species. New York: American Society of Mammalogists, 1969. N. pag. Print.
6. Emmons, L., and F. Feer. "Didelphidae." Neotropical Rainforest Mammals: A Field Guide. Chicago: U of Chicago, 1990. 13. Print.
7. Cable, R. "Caluromys Derbianus." Animal Diversity Web. N.p., 2013. Web. 02 May 2014.
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