Gray four-eyed opossums (Philander opossum) are Neotropical marsupials with a range that extends from northeastern Mexico in Tamaulipas, to southeastern Brazil. Within this range, they may be found from Brazil's Atlantic coast, westward into Peru and Argentina and throughout Central America in tropical lowlands and the Amazon and Parana basins. (Cerqueira, 1993; Fonseca and Cerqueira, 1991; Nowak, 1999; Patton and da Silva, 2007)
Gray four-eyed opossums are found mainly in tropical forested areas such as tropical evergreen, secondary growth and gallery forests. However, they may be found in the southern portions of South America, where the habitat is more temperate. These opossums generally prefer damp areas near swamps and streams and usually reside in areas that receive more than 1,000 mm of rain per year. Gray four-eyed opossums may also be found in highly disturbed habitats near human structures or within agricultural areas such as orchards and sugar cane fields. These animals generally prefer lowland areas and are usually found below 1,000 m in elevation. They are primarily terrestrial; however, they are also proficient swimmers and are occasionally found on islands as a result. (Adler and Saemon, 1996; Brito, et al., 2008; Castro-Arellano, et al., 2000; Fonseca and Cerqueira, 1991; Patton and da Silva, 2007)
The common name, gray four-eyed opossum, is derived from their gray coat and the white spots located above each eye, which makes them appear to have four eyes. The coloration of their short, straight, soft hair is gray dorsally and off-white to yellow ventrally. Their dorsal pelage may vary slightly with their location, for instance, individuals in Mexico tend to have pale gray fur, in Central America they have dark gray fur and in Columbia they have dark brown to blackish fur. Their prehensile tail has grayish fur covering the first 50 to 60 mm from the base, the tip of their tail is naked and pale as it narrows towards the end. These animals have dark masks around their eyes, in contrast to the white coloration of their cheeks and chin. Their large, hairless ears are black along the edges. Their body length is 200 to 331 mm; with a tail length of 195 to 355 mm. Females are slightly smaller and have seven mammae within their pouch. Gray four-eyed opossums have a slender body and a large head. Their rostrum is fairly long and narrows at the tip. Their hind limbs are longer and more muscular than the forelimbs. In the wild, adults weigh between 200 and 674 g, however, captive individuals can weigh up to 1,500 g. (Castro-Arellano, et al., 2000; Julien-Laferriere and Atramentowicz, 1990; Nowak, 1999; Vieira, 1997)
There is no specific information regarding the mating systems of gray four-eyed opossums. However, members of family Didelphidae are generally considered polygynous. Males compete for reproductive females, communicating with a series of clicking noises. Didelphids show neither courtship displays nor pair bonds. (Fernandes, et al., 2010; O'Connell, 2006)
Most populations of gray four-eyed opossums reproduce seasonally, although some may breed throughout the year, with lower levels from June to August. During the rainy season, fruit is plentiful and more young may be cared for, while during the dry season, fruit is rare and fewer young are born. Reproduction only ceases entirely when the mother's nutritional requirements are not met. These animals produce 2 to 4 litters per year, however, success is low; many pouch young do not survive, especially during the dry months. Although the gestation period of gray four-eyed opossums has not been reported, a close relative, southern four-eyed opossums (Philander frenatus), have a 13 to 14 day gestation period. Litter sizes vary from 1 to 7 young, with an average of 4 to 5 young, each weighing about 9 g. 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 (about 3.8). Females become sexually mature at about 6 to 7 months, while males become sexually mature around 7 months. (Adler and Saemon, 1996; Castro-Arellano, et al., 2000; Fleck and Harder, 1995; Hingst, et al., 1998; Julien-Laferriere and Atramentowicz, 1990; Nowak, 1999; Patton and da Silva, 2007)
Young gray four-eyed opossums nurse from their mother’s pouch, which contains 7 mammae. These offspring are weaned when they are 68 to 75 days old, or when they weigh between 50 to 75 grams. After being weaned, young often stay in the nest for an additional 8 to 15 days, during this time, females may become aggressive toward the young. (Castro-Arellano, et al., 2000; Hershkovitz, 1997)
Gray four-eyed opossums may live up to 2.5 years in the wild. In captivity, these animals may live for up to 3.5 years. (Castro-Arellano, et al., 2000)
Gray four-eyed opossums are primarily nocturnal; however, some populations, such as those in Suriname, exhibit diurnal activity patterns as well. These animals generally construct nests from dried leaves in the lower branches of trees, 8 to 10 m from the ground; however, nests may also be found on the ground, in burrows, in fallen logs and in abandoned homes. Their nests are globular in shape and have a diameter of approximately 30 cm. Although they are proficient climbers and swimmers, much of their activity is terrestrial. Gray four-eyed opossums use their pronounced hind limbs for scampering and jumping along the forest floor. After being released from capture, they usually use a terrestrial escape route rather than climbing trees. Unlike other opossum species, gray four-eyed opossums are often described as swift, agile and aware. (Adler and Saemon, 1996; Castro-Arellano, et al., 2000; Cerqueira, 1993; Fleck and Harder, 1995; Gentile and Cerqueira, 1995; Julien-Laferriere and Atramentowicz, 1990; Nowak, 1999; Vieira, 1997)
Although gray four-eyed opossums are solitary, these animals are generally not considered territorial, with overlapping home ranges and up to 150 individuals per km2. Their home ranges are not firmly established, animals may travel nomadically, particularly when food availability is low. In the Panama Canal Zone, their home range size was estimated at 3,400 m2. (Castro-Arellano, et al., 2000; Patton and da Silva, 2007)
Gray four-eyed opossums are not known as vocal animals, however, these animals do communicate with a series of clicks, chirps and hisses. Unlike many other opossum species, these animals do not ‘play possum’ when threatened, instead these animals will fiercely fight perceived threats. When they are in duress, they also make a series of threatening visual displays such as opening their mouths and hissing. Males also communicate with breeding females using sternal and abdominal scent glands. (Castro-Arellano, et al., 2000)
Gray four-eyed opossums are omnivorous. About half of their diet consists of small animals such as insects, earthworms, birds, lizards, eggs, frogs, crustaceans, snails and small mammals, particularly spiny rats. The remainder of their diet includes leaves, bark, seeds, nuts, nectar and fruits such as papayas, bananas, sweet lemons and jobo plums. Their diet varies seasonally, during the wet season, they consume more plant matter because it is more widely available, during the dry season, they are much more insectivorous. (Castro-Arellano, et al., 2000; Fleck and Harder, 1995; Fonseca and Cerqueira, 1991; Julien-Laferriere and Atramentowicz, 1990; Nowak, 1999; Patton and da Silva, 2007)
Gray four-eyed opossums are preyed upon by a variety of mammals, owls and large reptiles such as Amazon tree boas, South American bushmasters, ocelots, jaguarundis, tayras, greater grisons, gray foxes and barn owls. Compared to other species of opossums, these animals are extremely fierce fighters, defending themselves violently as needed. Likewise, the white fur spots located above their eyes gives the appearance of always being awake and vigilant, which may detract some predators. (Castro-Arellano, et al., 2000)
Gray four-eyed opossums are important dispersers for Cecropia seeds, particularly because they often deposit the seeds in high quality sites. Like most other opossum species, these animals carry a wide variety of internal and external parasites such as nematodes, trematodes, cestodes, fleas, mites, lice, ticks and chiggers. (Castro-Arellano, et al., 2000)
Gray four-eyed opossums help control insect and small vertebrate populations. In certain areas of Mexico, these animals are also hunted for food. (Castro-Arellano, et al., 2000; Fonseca and Cerqueira, 1991)
Gray four-eyed opossums occasionally feed on corn fields and fruit crops, damaging farmer’s fields. Likewise, these animals are reservoirs for Trypanosoma cruzi. (Castro-Arellano, et al., 2000; )
Currently, gray four-eyed opossums are considered a species of ‘least concern’ according to the IUCN Redlist of Threatened Species. Their conservation status was determined due to their large population size, large geographic range and tolerance to human disturbed environments. (Brito, et al., 2008)
Gray four-eyed opossums have a wide array of other common names such as tlacuache cuatro ojos, raton tlacuache gigante, zorrito de arbol, ooch, uc c’o, cayopolin, zorro de cuatro ojos, fo-ai awari, cucha gris de cuatro ojos, zorro, pericote, mucura-de-cuatro-olhos, carachupa, chucha mantequera, comadreja gris de cuatro ojos, Guaiki and mbicure. These animals are believed to have 4 subspecies, although it is under debate. The 4 currently recognized subspecies of gray four-eyed opossums include Pilander opossum canus, P.o. fuscogriseus, P.o. melanurus and P.o. opossum. (Castro-Arellano, et al., 2000; Patton and da Silva, 2007)
Leila Siciliano Martina (author, editor), Animal Diversity Web Staff.
Michael Waters (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
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.
an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).
uses smells or other chemicals to communicate
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.
parental care is carried out by females
A substance that provides both nutrients and energy to a living thing.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
an animal that mainly eats all kinds of things, including plants and animals
having more than one female as a mate at one time
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.
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
breeding takes place throughout the year
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