Four-Eyed Possums
There are three species of four-eyed opossum that occasionally show up in pet trade. All three require the same basic care however, and have those cute spots over their eyes giving them their four-eyed name.
Gray and Black “Four-eyed” Opossums
P. opossum (gray “four-eyed” opossum), from northeastern Mexico to northeastern Argentina; P. mcilhennyi (black “four-eyed” opossum), from central Peru. Head and body length is 250-350 mm, tail length is 253-329 mm, and adult weight in the wild is usually 240-400 grams. According to Collins (1973), however, healthy, well-fed captive males weighed 800-1,500 grams and females, 600-1,000 grams. The fur is rather straight and short in the gray (P. opossum) but much longer in the black (P. mcilhennyi). The upper parts are gray to black, with a white spot above each eye, and the underparts vary from yellowish to buffy white. The white spots above the eyes account for the vernacular name “four-eyed” opossum.
The tail, which is furred for about 50-60 mm from the rump and naked toward the tip, is black or grayish black on its basal half and white toward the end, with a pink tip. The body is slim and usually lean, and the head is large, with an elongate, conical muzzle. The ears are naked. The tail is slender, tapering, and prehensile. Females have a distinct pouch. The number of mammae varies from five to nine. These opossums inhabit forested areas and are often found near swamps and rivers.
They are smaller and more agile than Didelphis and quick in their actions. Although good climbers and swimmers, they are mainly terrestrial. All 46 specimens taken in Venezuela by Handley (1976) were caught in moist areas, nearly always on the ground. They build globular nests, about 30 cm in diameter, in the lower branches of trees or in bushes, and they may also inhabit ground nests and burrows. They are thought to be mainly nocturnal, though Husson (1978) stated that in Surinam they are as active in the day as at night. Their diet includes small mammals, birds and their eggs, reptiles, amphibians, insects, freshwater crustaceans, snails, earthworms, fruits, and probably carrion.
Occasional damage to fruit crops and cornfields has given them a bad reputation in certain areas. In Panama, Fleming (1972) found maximum population densities of 0.55-0.65 per ha. These opossums are not known to feign death when danger threatens, like Didelphis, but will open the mouth wide, hiss loudly, and fight savagely. When disturbed they may utter a long, chattering cry. The gray four-eyed opossum (P. opossum) reportedly breeds all year in some areas, possibly including Veracruz, Mexico, but is seasonal in others (Hunsaker and Shupe 1977). Collins (1973) cited records of females with pouch young being taken in Nicaragua from February to October, in Panama from April to July, and Colombia in June, September, and October. Jones, Genoways, and Smith (1974) caught a female with six nursing young in March on the Yucatan Peninsula. Phillips and Jones (1969) collected data indicating that the main reproductive season in Nicaragua extended from March through July.
Litter size there averaged 6.05 (3-7). According to Fleming (1973), the gray (P. opossum) is seasonally polyestrous in Panama, with two or more litters probably being produced by each female from January to November. Litter size averaged 4.6 (2-7). Husson (1978) found females with young in Surinam during January, March, and April. Litter size there ranged from 1 to 7 but averaged only 3.4. These records support the statement by Phillips and Jones (1969) that litter size tends to be larger in the north. Collins (1973) reported that the small pouch young of a female received on 7 May were weaned on 23 July, that first estrus in females occurred at 15 months of age, and that maximum known longevity for captives was only 2 years and 4 months.
Brown “Four-eyed” Opossum
The single species, M. nudicaudatus, is found from southern Nicaragua to northeastern Argentina. Because of technical problems of nomenclature, there has been recent argument regarding which generic name properly applies to this species. Hershkovitz (1976, 1981) supported Metachirus, which has been in more general use, while Pine (1973a) favored Philander Tiedemann, 1808, at least for the time being. Hall (1981) followed Pine in applying Philander to the brown “four-eyed” opossum, but Corbet and Hill (1986), Gardner (1981), Honacki, Kinman, and Koeppl (1982), and Kirsch and Calaby (1977) agreed with Hershkovitz. The generic designation Philander is actually applicable to the gray and black “four-eyed” opossums and is so employed here, again in accordance with Hershkovitz (1976, 1981) and his backers, rather than the name Metachirops, which was used by Pine (1973a) and Hall (1981). Head and body length is about 265 mm and tail length is approximately 330 mm. A male and a female from Barro Colorado Island, Panama Canal Zone, each weighed 800 grams.
The back and sides are brown, often dark cinnamon brown, and the rump may be washed with black. The face is dusky, almost black in some individuals, with a creamy white spot over each eye. These spots, suggesting eyes, are usually smaller and more widely separated than those of Philander. The underparts are buff to gray. The tail is furred for a short distance basally. The pelage is short, dense, and silky. Although the common names and general appearance of Metachirus and Philander are similar, the two are not closely related. Metachirus may be distinguished externally by its brown coloration and longer tail. Unlike the gray and black “four-eyed” opossums, the females of Metachiruslack a pouch, having instead simple lateral folds of skin on the lower abdomen, in which are located the mammae. Females with five, seven, and nine mammae have been recorded (Collins 1973). Kirsch (1977c) observed of didelphids, Metachirusis almost quiet when held in the hand.
The brown “four-eyed” opossum lives in dense forests or in thickets in open, brushy country. It builds round nests of leaves and twigs in tree branches but occasionally males its shelter under logs or rocks. Handley (1976) reported that all 18 specimens taken in Venezuela were caught on the ground, mostly near streams or in other moist areas. Members of this genus are completely nocturnal, rarely moving from the nest until dark. The diet includes fruits, insects, mollusks, amphibians, reptiles, birds, eggs, and small mammals. Metachirus has been accused of damaging fruit crops in some areas. Limited data indicate that this opossum is seasonally polyestrous (Fleming 1973). It reportedly breeds November in Central America, has litters of one to nine young, and probably has a maximum life span of three to four years (Hunsaker 1977b). The single, 51-mm young of a female obtained on 18 December was then already able to stand alone. It later rode on its mother’s back or hips and was fully independent by early February (Collins 1973).
