Andean white-eared opossums (Didelphis pernigra) are found in mountainous regions of northern and western South America including Venezuela, Columbia, Ecuador, Peru and Bolivia. This species may also be found in the northern portions of Argentina. (Cerqueira and Tribe, 2008; Lew, et al., 2008)
Andean white-eared opossums occupy varying habitats depending on a population’s range, although generally these animals prefer forested mountainous habitats. In Venezuela, Columbia and Bolivia this species is generally found in high elevation forests. In more western portions of this species range, they may be found in riparian areas at lower elevations. Andean white-eared opossums may survive in a wide range of human disturbed environments including farming areas, suburbs and open lands. (Cerqueira and Tribe, 2008; Lew, et al., 2008)
Andean white-eared opossums are member of the genus Didelphis. Until very recently, Andean white-eared opossums were included in Didelphis albiventris, along with Guianan white-eared opossums. In 2002, the white-eared opossum group was split into 3 separate species, white-eared opossums (Didelphis albiventris), Guianan white-eared opossums (Didelphis imperfecta) and Andean white-eared opossums (Didelphis pernigra). Due to this recent split, information regarding each of these new individual species is sparse. (Lemos and Cerqueira, 2002)
There have been very few published accounts detailing the physical appearance of Andean white-eared opossums. However, given that this species was grouped with Didelphis albiventris until very recently, it is likely that these species share many similarities. These opossums are relatively robust with pointed muzzles. Andean white-eared opossums can be distinguished by the stark whiteness of their facial fur and their more pronounced black facial markings; they also have long black guard hairs throughout their pelage. Andean white-eared opossums have completely white ears that are naked and elongated. These species have prehensile tails that are largely hairless and scaly, with the exception of fur at the base of the tail and a bit of sparse fur throughout. They have a pronounced sagittal crest and the following dental formula: 5/4, 1/1, 3/3, 4/4. Females have a marsupium with 13 mammae. (Cerqueira and Tribe, 2008; Lemos and Cerqueira, 2002; Oliveira-Santos, et al., 2008; Smith, 2007; de Almeida, et al., 2008)
There is no specific information regarding the mating systems of Andean white-eared 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)
There is little published information specifically regarding the reproductive behavior of Andean white-eared opossums. However, there appears to be little behavioral variation in the studied members of their genus. These species typically have 2 breeding periods; breeding generally begins at the end of the dry season and offspring are born during the wet season. The gestation period for these species tends to be very short, about 12 to 14 days on average. The specific number of young produced by Andean white-eared opossums is not known, however, their close relative Didelphis albiventris typically has 4 to 23 young. These offspring are extremely altricial; they are often about 15 mm long and weigh about 0.13 grams. (O'Connell, 2006; Rademaker and Cerqueira, 2006; Smith, 2007; Talamondi and Dias, 1999)
The parental investment of Andean white-eared opossums has not been reported, however, research has been conducted on their close relative, white-eared opossums (Didelphis albiventris). Once the offspring of white-eared opossums are born, they must climb to the marsupium. Although a female may have many offspring within a litter, their marsupium only includes 13 mammae, as such, many of these altricial young will not survive. Young white-eared opossums remain within the pouch attached to the mammae for the first two months of their life, after which, they cling to their mothers back. They will stay with their mother for several more weeks; they are weaned at 3 to 4 months of age. White-eared opossums are sexually mature at around 9 months. (Cerqueira and Tribe, 2008; Rademaker and Cerqueira, 2006; Smith, 2007)
The lifespan of Andean white-eared opossums has not been reported, although they are frequent victims of car collisions. Most didelphids have a very short lifespan, for instance, white-eared opossums typically do not survive beyond 20 months of age. (Delgado V, 2007; Smith, 2007)
The behavior of Andean white-eared opossums has not been reported. However, their close relatives Guianan white-eared opossums are solitary, although they may feed in similar areas with conspecifics, they do not interact. They are primarily terrestrial, but they are also adept climbers. These animals are nocturnal. During daylight hours Guianan white-eared opossums take shelter in abandoned termite nests, hallow trees or in the tree canopy, likewise, they may build leaf nests or burrow for refuge. (Lew, et al., 2008; O'Connell, 2006; Rademaker and Cerqueira, 2006)
The home range size of Andean white-eared opossums has not been reported.
The perception channels of Andean white-eared opossums have not been reported, however, research has been conducted on other members of genus Didelphis. White-eared opossums primarily detect food items using their olfactory and auditory senses. In general, members of genus Didelphis also have very good eyesight. Likewise, members of this genus are equipped with long whiskers, which help them to navigate at night. When these animals perceive a threat they typically bare their teeth, they can also run rather quickly when they are on the ground, their speed is impaired when they are climbing. In somewhat rare cases, when white-eared or Virginia opossums perceive an extreme threat, they may feign death. (O'Connell, 2006; Oliveira and Santori, 1999; Smith, 2007)
There has been no published information regarding the food habits of Andean white-eared opossums, however, there is a great deal of information regarding their close relative, white-eared opossums (Didelphis albiventris). White-eared opossums are omnivorous opportunistic feeders. They primarily feed on invertebrates, however, their diet changes based on food availability. Their diet components are generally as follows: 33% invertebrates, 28% vegetation including leaves, grasses and fibers, 17% birds, 12% fruits and seeds, 6% other vertebrates and 4% unknown. Among invertebrates, white-eared opossums typically feed on beetles, millipedes and dung beetles. Although both adult and young white-eared opossums have similar diets, adults are more likely to capture and consume vertebrate prey. When feeding, white-eared opossums sit in a semi-erect position, when consuming invertebrates and vertebrates, these animals typically eat the heads first. (Alessio, et al., 2005; Caceres, 2002; Oliveira and Santori, 1999; Oliveira-Santos, et al., 2008; Smith, 2007; Talamondi and Dias, 1999)
There are no specific reports regarding predation of Andean white-eared opossums, however, white-eared opossums are predated upon by a variety of animals including maned wolves, felines, foxes, roadside hawks, barn owls, yellow anacondas and boa constrictors. Likewise, juvenile white-eared opossums may be prey for various adult snakes and great horned owls (Jacomo, et al., 2004; Oliveira and Santori, 1999; Smith, 2007; Tomazzoni, et al., 2004)
Although it has not been specifically reported for Andean white-eared opossums, their close relative white-eared opossums are important seed dispersers, specifically for pioneer plants. Other members of genus Didelphis are known to be reservoirs for numerous ecto- and endoparasites including nematodes, trematodes, protozoans, ticks, mites and fleas, however, parasites specific to Andean white-eared opossums have not been reported. (Caceres, 2002; Cerqueira and Tribe, 2008; Fornazari, et al., 2011; Quintal, et al., 2011; Smith, 2007)
There are no known positive impacts of Andean white-eared opossums on human populations.
There are no known negative impacts of Andean white-eared opossums on human populations.
Andean white-eared opossums are currently listed as a species of least concern according to the IUCN Red List of Threatened Species. This species is found in a wide range and likely has a fairly large population size throughout. (Lew, et al., 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.
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.
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
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.
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.
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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