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Didelphis virginiana - Virginia opossum

Skull Pictures:               

Dorsal      Mandible
Lateral     Posterior Mandible
Ventral

Physical Description:

Adult opossums can range in size from 24 to 33 inches and they weigh between 6 and 15 pounds with the males generally being slightly larger than the females.  Opossums have short legs relative to their body size.  Opossums are covered with long grey to black hairs with white tips.  This variation in color gives the opossum a dark to grayish-silver coloration.  They have long tapered muzzle and their face, neck and underbelly are a white to yellowish-white color.  The ears and tail of an opossum are naked.  The tail is black for the first few inches and then fades to a white or a cream skin color.  The typical dental formula for the opossum is as follows:
(Lyon 1936).

 Distribution:

The Virginia opossum ranges north and south from New York to Florida. They range east and west from the Atlantic coast to the Midwest and down through Texas and into Mexico (Lyon 1936).  The only place in the U.S. where the opossum is not found is in the upper northwest.  All of Wisconsin is considered prime habitat for the opossum. 

Ontogeny and Reproduction:

Opossums have dentition that suggests omnivory, which is the case for the species.  Opossums can survive on a wide-ranging diet.  They consume flesh in the form of dead animals, birds and their eggs, frogs, worms, snails, etc.  They also eat berries and fruits when present. In agricultural areas they feed on corn. In areas where opossums have urbanized they subside on refuse and waste from neighborhood garbage cans.  This ability to adapt to a wide variety of foods is part of the reason why opossums are so far ranging.  Most foraging is done at night throughout their home range.  Males typically have a home range of about 105 ha.  The females’ home range is much smaller averaging approximately 51 ha. (Gillette 1980).

The opossum is North America’s only marsupial. One important character of marsupials is that they have an epipubic bone attached to the pelvis (Lyon 1936). The female has a posterior opening pouch which contains 13 teets for nourishing young.  Following a brief gestation of only 12 to 13 days the young are born and immediately crawl to the pouch and begin nursing.  A typical litter consists of 12 to 22 offspring.  Those that are not able to locate and attach to a teet die of starvation.

Ecology and Behavior:

Opossums prefer to live near a constant source of water such as a river or stream.  They nest in standing snags as well as fallen trees and the abandoned burrows of other animals. Opossums prefer edge habitat over large expansive forests.  Many times they are found near agricultural fields that produce corn. In urban environments they have been found to nest in tool sheds and barns.  Their ability to adapt and use a variety of nest sites is another reason why the opossum is so far ranging.

Opossums are usually not social unless they are actively looking to mate. Males remain ready to mate throughout the year and must wait for the female to come into estrous to breed (Winegarner 1982). They are slow moving and quiet animals. Opossums are mostly nocturnal or diurnal.  They are not aggressive except for females immediately before and after estrous.  One interesting character of the opossum is their defensive behavior.  When confronted an opossum will roll over and remain motionless as if feigning death.  This curious behavior has coined the phrase “playing possum” (McManus 1970).

Remarks:

Opossums were at one time valued for their fur, which was used to make cuffs and collars for jackets and coats.  They are still trapped by some and eaten although they are not regarded as a prime source of nutrition.  They are hunted primarily in the southern U.S. at night with the aide of hounds and spotlights (Lyon 1936).

Literature Cited:

McManus, J.J.  1970.  Behavior of Captive Opossums, Didelphis marsupialis virginiana.  American Midland Naturalist 84(1): 144-169.

Lyon Jr, M.W.  1936.  Mammals of Indiana.  American Midland Naturalist 17(1):  1-373.

Ladine, T.A. and Kissell Jr, R.E.  1994.  Behavior of Escape Virginia Opossums.  American Midland Naturalist 132(2):  234-238.

Allen, C.H. et al.  1985.  Movement, Habitat Use and Denning of Opossums in the Georgia Piedmont (in Notes and Discussion).  American Midland Naturalist 113(2): 408-412.

Gillette, L.N.  1980.  Movement Patterns of Radio-Tagged Opossums in Wisconsin.  American Midland Naturalist 104(1): 1-12.

Winegarner, M.S.  1982.  Seasonal Changes in the Reproductive Tract of the Male Opossum Didelphis virginiana Kerr in Florida.  American Midland Naturalist 107(2): 258-261.

 Reference written by Michael Hawley, Biol 378: Edited by Chris Yahnke and Jen Callahan.
Page last updated 4-23-04.

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