Common opossums are found in a variety of habitats throughout Central and South America. These animals are considered habitat generalists and are even tolerant of anthropogenically altered environments. They are not found in areas of exceptionally high elevation or extremely dry habitats, although they are found in montane environments in Costa Rica and may survive in areas with a wide range of precipitation. It has been suggested that common opossums may be the most tolerant and adaptable Neotropical mammal. Their preferred habitats include tropical, subtropical, old growth, evergreen and gallery forests in lowland regions below about 2,000 meters on average. These animals also frequent urban environments such as near human dwellings and garbage dumps, as well as agricultural lands including pastures and cacao, coffee and citrus plantations. Common opossums may be found on the ground or in large trees, although they are more terrestrial than some members of their genus. (Adler, et al., 2012; Brito, et al., 2008; Cerqueira and Tribe, 2008; Estrada, et al., 1994; Medellin, 1994; Reid, 2009; Tyndale-Biscoe, 1973)
Common opossums are robust marsupials. The fur on their body is thick with long guard hairs, leading these animals to appear somewhat disheveled. Their dorsal pelage is often dark, typically blackish or grayish, but in rare instances they may appear whitish. In comparison, their ventral fur is yellow or cream. These animals have primarily whitish fur on their faces and a dark stripe extending to the crown of their heads, with a black ring around both eyes. Their ears are large and all black. Common opossums have sharp claws, long whiskers and a primarily naked prehensile tail that is slightly longer than their body. These animals are sexually dimorphic; males trapped in French Guiana averaged 1.2 kg, whereas females averaged 1.03 kg. These values may be low; other sources suggest that their body weights range between 4 to 6 kg. In general, adult males have longer canines than adult females. Common opossums typically have a total body length of 371 mm (ranging from 265 to 430 mm), including a tail length of 395 mm. (Castillo-Flores and Calvo-Irabien, 2003; Reid, 2009; Richard-Hansen, et al., 1999; Shripat, 2011; Tyndale-Biscoe and Renfree, 1987)
Common opossums show a polygynous mating system, in which males compete for reproductive females. These animals are almost exclusively solitary, but come together seasonally for breeding. Didelphids do not exhibit courtship rituals and do not pair bond. Females experience a 25 to 32 day estrous cycle. When resources are limited or unavailable these animals may choose not to mate. (Fernandes, et al., 2010; Julien-Laferriere and Atramentowicz, 1990; O'Connell, 2006; Shripat, 2011; Sunquist, et al., 1987)
Breeding seasons and the number of annual litters varies based on latitude. Breeding seasons can vary from one long season from January to September or several shorter seasons annually. These seasons may be correlated with seasonal precipitation. Female common opossums begin breeding when they are 6 to 7 months old. Gestation typically lasts 13 to 15 days, after which 2 to 20 altricial young are born, interestingly; animals living closer to the equator tend to have smaller litters. At birth, their young are tiny; they are usually about 1 cm long and weigh about 0.13 grams. Although they are extremely under-developed, newborn common opossums have well-developed claws on their front legs that help them climb to their mother’s pouch. Once inside the pouch, their young remain attached to the mammae for about 50 days. Young are weaned and independent when they are 90 to 125 days old, often when fruit is plentiful. (Brito, et al., 2008; Cabello, 2006; Gustavo, et al., 1990; Julien-Laferriere and Atramentowicz, 1990; O'Connell, 2006; Shripat, 2011; Tyndale-Biscoe and Mackenzie, 1976; Tyndale-Biscoe and Renfree, 1987; Tyndale-Biscoe, 1973; Tyndale-Biscoe, 2005)
Common opossums offer very little parental care. Males have no involvement in raising their offspring and females invest a minimal effort. When their tiny offspring are born, they begin a harrowing journey to their mother’s pouch; many of the young will not survive. Female common opossums typically only have 9 teats available for nursing, so they often have more offspring than they can accommodate. However, they have a fairly low mortality rate once they are safely inside the pouch and nursing. The young may begin leaving the pouch when they are about 70 days old, at which time they may begin riding on their mother’s back while she forages. The young become independent when they are weaned between 90 and 125 days old. Interestingly, a study in Venezuela determined that females with ample resources are more likely to have mostly male offspring, whereas, when resources become limited they typically have a greater number of females in their litters. (Austad and Sunquist, 1987; Julien-Laferriere and Atramentowicz, 1990; Shripat, 2011; Tyndale-Biscoe and Mackenzie, 1976; Tyndale-Biscoe and Renfree, 1987)
Common opossums are very short lived; they typically live fewer than 2 years. In a long term study of these animals, the oldest individual lived to be 20 months old, in another study; the oldest individual lived to be 11 months old. These animals experience their greatest mortality rate prior to maturity and while lactating. Common opossums are frequent victims of collisions with cars. (Kajin, et al., 2008; Pinowski, 2005; Reid, 2009; Sunquist, et al., 1987)
Common opossums are solitary and nocturnal. They begin their daily activities about an hour before sunset; however, their activity level peaks from 11 pm to 3 am. These animals are primarily terrestrial but spend a significant amount of time in trees, although other members of their genus are much more arboreal. During daylight hours, common opossums stay inside their burrows. Burrow locations vary and include tree cavities, underground, in palm or fig trees, in the tree canopy or in the abandoned nests of other species. These animals do not maintain a burrow for very long, males remain in the same den for about 1.5 days on average and females remain in the same den for about 5.1 days. (Adler, et al., 2012; Brito, et al., 2008; Julien-Laferriere and Atramentowicz, 1990; Reid, 2009; Shripat, 2011; Sunquist, et al., 1987; Vaughan, et al., 1999)
Male common opossums maintain a much larger home range than their female counterparts. Females average 16.3 hectares (+/- 8.2 ha), whereas males average a home range of 123 hectares (+/- 60.8 ha). Male home ranges overlap; generally there is about one individual per hectare. (Brito, et al., 2008; Sunquist, et al., 1987)
Common opossums use a variety of perception channels. Their auditory ability develops relatively late in life, young do not fully develop their auditory capabilities until they are about 80 days old. Common opossums may communicate vocally, specifically when they are engaged in an aggressive encounter. In such circumstances, these animals may hiss, growl or screech. Common opossums also perform a variety of visual displays when engaged in an aggressive interaction including rocking from side to side, drooling, baring their teeth, and in the case of an extreme threat, these animal have also been known to enter a catatonic state, commonly known as ‘playing opossum’. Olfaction is also used to communicate; common opossums may produce a secretion from their anal gland or spray urine and feces when a threat is perceived. Their vision is acute and is likely on par with the visual abilities of cats; however, their visual acuity is limited when compared to some primates. (Ehret, 1983; Oswaldo-Cruz, et al., 1979; Reid, 2009; Shripat, 2011; Volchan, et al., 2004)
Common opossums have a very broad diet. Their feeding habits are often referred to as opportunistic omnivory. Their diet includes invertebrates, vertebrates, leaves, fruits, nectar and carrion. Common opossums may alter their diet seasonally, during the dry season mammals and birds are more likely consumed, whereas during the wet season they rely more heavily on fruits, snakes and toads. Regardless of the season, invertebrates are a primary staple of their diet including earthworms, beetles and grasshoppers. After weaning, their diet remains fairly constant throughout their life, although older animals tend to consume vertebrates more frequently. Common opossums eat a variety of vertebrates including birds such as lance-tailed manikins, amphibians such as cane toads, reptiles such as Venezuelan rattlesnakes and a variety of small mammals. Interestingly, their ability to consume rattlesnakes is facilitated by their apparent immunity to the venom of many members of family Vipiridae. (Almeida-Santos, et al., 2000; Cerqueira and Tribe, 2008; Cordero and Nicolas, 1987; Garrett and Boyer, 1993; Reid, 2009; Reidy, 2009)
Given their abundance, common opossums are likely prey for a variety of large mammals throughout Central and South America. Their known predators include ocelots, jaguarundis and harpy eagles. When a threat is detected, common opossums may choose to run or climb a tree to evade predators. Less frequently, these animals may enter a catatonic state, commonly known as 'playing opossum'. This death feigning behavior may last as little as 1 minute or as long as 6 hours. (Gustavo, et al., 1990; Rotenberg, et al., 2012; Shripat, 2011)
Common opossums carry a variety of parasites; some reports claim they may carry up to 46 species of internal and external parasites. Most notably, Trypanosoma cruzi may be found in their anal glands. They also carry a variety of cestodes, nematodes and acanthocephala in their large and small intestines. Common opossums are also important seed dispersers. They move some seeds due to ingestion after eating fruits, such as for Cecropia. However, their shaggy fur also causes them to transport diasporas from Pavonia schiedeana and Desmodium incanum. These plants are anthropogenic herbs and have been introduced to the forest understory partially via the fur of animals. (Castillo-Flores and Calvo-Irabien, 2003; Cerqueira and Tribe, 2008; Deane, et al., 1984; Jimenez, et al., 2011; Medellin, 1994)
Common opossums are often hunted by humans. They are killed for sport and food and are even part of the illegal wild game trade. Some cultures believe that the fat of common opossums can be used to treat a variety of ailments including stomach aches, rheumatism, diarrhea, inflammation, skin infections, labor pains, asthma, headaches, toothaches, ear aches and sore throats. (Alves and Rosa, 2006; Alves and Rosa, 2007; Brito, et al., 2008; Junior, et al., 2010)
Common opossums are known to transmit diseases which impact human populations, such as Chagas disease and leishmaniansis. These animals may also be considered pests due to their aptitude for killing bats caught in research mist nets and their proclivity for poultry. (Brito, et al., 2008; Cabello, 2006; Deane, et al., 1984; Reid, 2009)
Common opossums are currently listed as a species of least concern according to the IUCN Red List of Threatened Species. These animals are found throughout much of Central and South America and likely have a very large population size. Their ability to live in anthropogenically disturbed environments facilities this species broad success. (Brito, et al., 2008)
South American didelphids are commonly grouped into either ‘white-eared’ or ‘black-eared opossums’. Common opossums ( ) are included in the ‘black-eared opossum’ group, along with big-eared opossums (Didelphis aurita). (Cerqueira and Tribe, 2008)
Leila Siciliano Martina (author), Animal Diversity Web Staff.
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.
flesh of dead animals.
either directly causes, or indirectly transmits, a disease to a domestic animal
uses smells or other chemicals to communicate
active at dawn and dusk
a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease
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.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
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.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
living in residential areas on the outskirts of large cities or towns.
uses touch to communicate
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
living in cities and large towns, landscapes dominated by human structures and activity.
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.
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