Summer 2003
American Opossums - 1

 

MARSUPIALIA Family DIDELPHIDAE

The Didelphidae genera consist of the following

CALUROMYS (Woolly Opossums)                   

CHIRONECTES (Water Opossum, or Yapok)

CALUROMYSIOPS (Black-shouldered Opossum)

DIDELPHIS (Large American Opossums)

GLIRONIA (Bushy-tailed Opossum)

LUTREOLINA (Thick-tailed Opossum)

LESTODELPHYS (Patagonian Opossum)

METACHIRUS (Brown "Four-eyed" Opossum)

MARMOSA (Murine, or Mouse, Opossums)

MONODELPHIS (Short-tailed Opossums)

PHILANDER (Gray and Black "Four-eyed" Opossums)

 Gray Four-Eyed Opossum

(Philander Opossum)

by

Michael Waters
University of Michigan

Classification

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Didelphimorphia

Family: Didelphidae

Subfamily: Didelphinae

Genus: Philander

Species: Philander opossum

 

Geographic Range

Neotropical: Philander opossum has a range that extends from Northeastern Mexico to Southeatern Brazil. Within this range, P. opossom may be found from Brazil’s Atlantic coast westward into Peru and Argentenia, as well as throughout Central America. (Nowak 1997, Fonseca 1991, Cerqueira 1993) 

Physical Characteristics

Mass: 220 to 680 g.

The common name is derived from this opossum’s grey coat and the single white spots which are located directly above each eye, providing it with an appearance of four eyes.

The body length is 250-350 mm, and the tail reaches to about the same length.  Males may be slightly larger than females, although much overlap in size is present. Females have five to nine mammae contained within a pouch.  The coloration of the short, straight hair is gray dorsally and off-white to yellow ventrally. The tail is furred with the same gray coloration for 50-60 mm from the base. The tip of the tail is naked and becomes paler in color towards its end.    The ears are naked as well.

Philander opossum has a slender body and a large head. Its rostrum is fairly long and narrows at the tip. The tail tapers as well, and it is prehensile. The hind limbs are longer and more muscular than the forelimbs. (Vieira 1997, Nowak 1997, Julien-Laferriere 1990) 

Natural History

1        Food Habits

Philander opossum is omnivorous. About half of its diet consists of small animals such as insects, earthworms, birds, lizards, eggs, frogs, and small mammals. The remainder of the diet includes leaves, seeds, and fruits such as papayas and bananas. (Fleck 1995, Julien-Laferriere 1990, Nowak 1997, Fonseca 1991)

 

2        Reproduction

Most populations of this species reproduce seasonally. During the rainy seasons, fruit is plentiful and more young may be cared for, while during the dry seasons, fruit is rare and few young are born. However, Philander opossum does reproduce throughout the year, but at lower levels during the months of June to August. Reproduction only ceases entirely when the mother’s nutritional requirements are not met.

 

Although reproduction occurs year round, success is low. Death of young within the mother’s pouch is common, especially during the dry months.  The young nurse in the mother’s pouch, as that is where the nipples are located. Lactation lasts approximately 90 days, with much growth occurring after the weaning period. Following weaning, young P. opossum increase their body mass by a factor of ten.

 

Litter sizes vary from 1 to 7 young with the average litter containing 4 or 5 young. Larger females, those over 445 grams, tend to have larger litters (about 5 per birth), while smaller females, those under 445 grams, have fewer young per birth (about 3.8).
 

Females become sexually mature at about 6 to 8 months. At this time they weigh over 200 grams. Life expectancy is one to two years. (Julien-Laferriere 1990, Fleck 1995, D’Andrea 1994, Nowak 1997, Adler 1996)

 

3.       Behavior

Philander opossum can be found in dense populations that exhibit low mobility.  While its range may extend as much as 300 meters, over fifty percent of the movements of this species occur within 30 meters.  Nests may be located on the ground or in burrows, but the majority of nests are built in the lower branches of trees, 8 to 10 meters from the ground. They are globular in nature and have a diameter of approximately 30 cm. While they usually nest in trees, much of the activity of these opossums is terrestrial.  Philander opossum uses its more pronounced hind limbs for scampering and jumping along the forest floor. After being released from capture, P. opossum usually uses a terrestrial escape route rather than climbing trees. It is proficient at climbing and swimming.
 

Philander opossum is thought to be nocturnal; however, some researchers have witnessed an equal amount of activity in the day. When provoked, P. opossum gives a loud cry or hiss, and it is capable of savagely fighting. (Fleck 1995, Julien-Laferriere 1990, Vieira 1997, Cerqueira 1993), Nowak 1997, Adler 1996), Gentile 1995)

 

4.       Habitat

Philander opossum is found mainly in tropical forested areas, however, they may be found in the southern portions of South America in which the habitat is more temperate. In general, P. opossum resides in areas that receive greater than 1000 mm of rain per year.

Due to its proficient swimming ability, P. opossum may be found on islands.

(Fonseca 1991, Adler 1996)

Biomes: tropical rainforest, tropical deciduous forest, tropical scrub forest. 

Economic Importance for Humans

1.       Positive

Philander opossum helps control the populations of insects and other small vertebrates. (Fonseca SD)

 

2.       Negative

Philander opossum has been known to feed upon corn fields and fruit crops, damaging farmers fields. (Nowak 1997)  

Conservation Status:

IUCN: No special status

U.S. ESA: No special status

CITES: No special status

Currently Philander opossum is not thought to be threatened. 

References

Adler, GH and JO Saemon. 1996. Distribution of Four-eyed Opossum, Philander opossum on Small Islands in Panama. Mammalia 60(1):91-99. 

Cerqueira, R, etc. 1993. A Five-year Population Study of an Assemblance of Small Mammals in Southeastern Brazil. Mammalia 57(4):507-517. 

D’Andrea, PS, R Cerqueira and ED Hingst. 1994. Age Estimation of the Gray Four-eyed Opossum, Philander opossum. Mammalia 58(2):283-291. 

Fleck, DW and JD Harder. 1995. . Jounal of Mammalogy 76(3):809-818. 

Fonseca, SD and R Cerqueira. 1991. Water and Salt Balance in a South American Marsupial, the Gray Four-eyed Opossum (Philander opossum). Mammalia 55(3):421-432.

Gentile, R and R Cerqueira. 1995. Movement Patterns of Five Species of Small Mammals in a Brazilian Restinga.. Journal of Tropical Ecology 11:671-677. 

Julien-Laferriere, D and M Atramentowicz. 1990. Feeding and Reproduction of Three Didelphid Marsupials in Two Neotropical Forests (French Guiana).  Biotropica 22(4):404-415.

Nowak, RM. 1997. “Walker’s Mammals of the World” (On-line), Available at http://www.press.jhu.edu/books/walkers mammals of the w.../ (December 8, 1999)

Vieira, MV. 1997. Body Size and Form in Two Neotropical Marsupials. Mammalia 61(2):245-254.

 This article is reproduced with many thanks and acknowledgements to the author, and the University of Michigan Animal Diversity Web.

Here are a some of examples of the Didelphis Opossum.

please click on thumbnails to enlarge

Photos 1. & 2 Unfortunately I have been unable to find the photographer responsible for these pictures therefore I am unable to offer acknowledgements.   If he/she sees these and recognises them I would be grateful if they would contact me so we can offer our thanks and appropriate acknowledgements.

Photos 3. & 4. courtesy of Sugarbane  see http://www.sugarbane.com

 
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