Guianan white-eared opossums (Didelphis imperfecta) are found in northern to central South America. This species is endemic to Guyana, Suriname, French Guiana, Venezuela and Brazil, however, they are likely also found in western Ecuador and northeastern Peru. (Cerqueira and Tribe, 2008; Lew, et al., 2011)
Guianan white-eared opossums are found at a variety of elevations. They may inhabit lowland rainforests at elevations as low as 60 m, or elfin forests on tepuis, or mesas, as high as 2,550 m. This species is known to inhabit the Venezuelan mountain, Cerro Marahuaca. (Cerqueira and Tribe, 2008; Lew, et al., 2011)
Guianan white-eared opossums are member of the genus Didelphis. Until very recently, Guianan white-eared opossums were included in Didelphis albiventris, along with Andean 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 Guianan 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. The fur on their faces has a dusty-whitish hue, with a dark gray medial stripe. Guianan white-eared opossums typically have whitish ears and a pointed muzzle. Their prehensile tails are largely hairless and scaly, with the exception of fur at the base of the tail and a bit of sparse fur throughout. These species 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 and Santori, 1999; Smith, 2007; de Almeida, et al., 2008)
There is no specific information regarding the mating systems of Guianan 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 Guianan 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 Guianan 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 Guianan 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 Guianan white-eared opossums has not been reported, however, most didelphids have a very short lifespan. For instance, white-eared opossums typically do not survive beyond 20 months of age. (Smith, 2007)
Guianan white-eared opossums are solitary marsupials, 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., 2011; O'Connell, 2006; Rademaker and Cerqueira, 2006)
The home range size of Guianan white-eared opossums has not been reported.
The perception channels of Guianan 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 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 Guianan 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: 39% invertebrates, 28% vegetation including leaves, grasses and fibers, 17% birds, 12% fruits and seeds 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 Guianan 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 Guianan white-eared opossums, their close relative white-eared opossums are important seed dispersers, specifically for pioneer plants. Guianan white-eared opossums are commonly infested with the protozoans Trypanosoma cruzi and species of Leishmania. Other members of genus Didelphis are known to be reservoirs for numerous ecto- and endoparasites including nematodes, trematodes, ticks, mites and fleas. (Caceres, 2002; Cerqueira and Tribe, 2008; Fornazari, et al., 2011; Quintal, et al., 2011; Smith, 2007)
There are no known positive impacts of Guianan white-eared opossums on human populations.
There are no known negative impacts of Guianan white-eared opossums on human populations.
Guianan white-eared opossums are currently listed as a species of least concern according to the IUCN Red List of Threatened Species. These animals are believed to have a sizable and steady population. (Lew, et al., 2011)
Didelphis albiventris was split into 3 separate species in 2002, although there is some disagreement about the status of Didelphis imperfecta as a distinct species. (Lemos and Cerqueira, 2002; Lew, et al., 2011)
Leila Siciliano (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
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 that mainly eats meat
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.
An animal that eats mainly insects or spiders.
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
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
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.
Alessio, F., A. Pontes, V. da Silva. 2005. Feeding by Didelphis albiventris on tree gum in the northeastern Atlantic forests of Brazil. Mastozoologia Neotropical, 12:1: 53-56.
Caceres, N. 2002. Food habits and seed dispersal by the white-eared opossum Didelphis albiventris in southern Brazil. Studies on Neotropical Fauna and the Environment, 37: 1-8.
Fernandes, F., L. Cruz, E. Martins, S. dos Reis. 2010. Growth and home range size of the gracile mouse opossum Gracilinanus microtarsus (Marsupialia: Didelphidae) in Brazilian cerrado. Journal of Tropical Ecology, 26:2: 185-192.
Fornazari, F., C. Teixeira, R. da Silva, M. Leiva, S. de Almeido, H. Langoni. 2011. Prevalence of antibodies against Toxoplasma gondii among Brazilian white-eared opossums (Didelphis albiventris). Veterinary Parasitology, 179:1: 238-241.
Jacomo, A., L. Silveira, J. Diniz-Filho. 2004. Niche separation between the maned wolf (Chrysocyon brachyurus), the crab-eating fox (Dusicyon thous) and the hoary fox (Dusicyon vetulus) in central Brazil. Journal of Zoology, 262: 99-106.
O'Connell, M. 2006. American Opossums. Pp. 808-813 in D MacDonald, S Norris, eds. The Encyclopedia of Mammals, Vol. 1. London: The Brown Reference Group.
Oliveira-Santos, L., M. Tortato, M. Graipel. 2008. Activity pattern of Atlantic forest small arboreal mammals as revealed by camera traps. Journal of Tropical Ecology, 24: 563-567.
Quintal, A., E. Ribeiro, F. Rodrigues, F. Rocha, L. Floeter-Winter, C. Nunes. 2011. Leishmania spp. in Didelphis albiventris and Micoureus paraguayanus (Didelphimorphia: Didelphidae) of Brazil. Veterinary Parasitology, 176: 112-119.
Smith, P. 2007. White-eared opossum Didelphis albiventris. Fauna Paraguay Handbook of the Mammals of Paraguay, 1: 1-19. Accessed May 07, 2013 at http:www.faunaparaguay.com/mam1Didelphisalbiventris.pdf.
Talamondi, S., M. Dias. 1999. Population and community ecology of small mammals in southeastern Brazil. Mammalia, 63:2: 167-181.
Tomazzoni, A., E. Pedo, S. Hartz. 2004. Food habits of great horned owls (Bubo virginianus) in the breeding season in Lami Biological Reserve, southern Brazil. Ornithologia Neotropical, 15: 279-282.
de Almeida, A., C. Torquetti, S. Talamoni. 2008. Use of space by Neotropical marsupialDidelphis albiventris (Didelphimorphia: Didelphidae) in an urban forest fragment. Revista Brasileira de Zoologia, 25:2: 214-219.