Despite their relative abundance, few data exist regarding the mating strategies employed by this species as opossums primarily are nocturnal and socially solitary (Ryser 1995; Gardner and Sunquist 2003). Didelphis virginiana (Virginia Opossum) is a species of mammals in the family Didelphidae. The Virginia opossum is the original animal named "opossum". Mating occurs between January and July. [10] They are one of the world's most variably sized mammals, since a large male from northern North America weighs about 20 times as much as a small female from the tropics. The estrous cycle averages about 30 days (McManus 1974). In a soft medium, such as the mud in this photograph, the foot pads clearly show (these are the deep, darker areas where the fingers and toes meet the rest of the hand or foot, which have been filled with plant debris by wind due to the advanced age of the tracks). Results of radiotelemetry studies suggest that Virginia opossums likely employ a promiscuous mating system, with males maximizing their reproductive success by mating with as many females as possible (Ryser 1992). Early researchers proposed that opossums were nomadic or solitary wanderers with unstable home ranges (Lay 1942; Reynolds 1945), whereas recent studies using radio transmitters have identified well-defined home range boundaries (Gillette 1980; Ryser 1995; Gipson and Kamler 2001). Maternal care in the opossum probably ceases at weaning, maximally 110 days post- partum (Hartman, 1928). The remaining 11 loci (OP03, OP08, OP14, OP16, OP18, OP19, OP36, OP39, OP42, OP46, and OP48) were used in subsequent statistical analyses. [47][48], An early description of the opossum comes from explorer John Smith, who wrote in Map of Virginia, with a Description of the Countrey, the Commodities, People, Government and Religion in 1608 that "An Opassom hath an head like a Swine, and a taile like a Rat, and is of the bignes of a Cat. Thirteen microsatellite loci (OP03, OP08, OP14, OP16, OP18, OP19, OP30, OP36, OP39, OP41, OP42, OP46, and OP48; Fike et al. Of the 572 offspring evaluated for evidence of paternity, CERVUS identified 13 unique fathers for 14 litters (1 male sired 2 separate litters) with no mismatches at any loci from within our sampled population of 317 males. Male Virginia opossums possess a sexually dimorphic scent gland on their chest, which emits a musky odor and stains their fur; this is most commonly observed near the onset of the breeding season. Female opossums have a forked (bifurcated) reproductive tract with two lateral vaginal canals and two uteri. Opossums have 13 nipples, arranged in a circle of 12 with one in the middle. The reason opossums have so many babies to insure that some of them survive. Opossums have sharp claws that help them dig into the bark of trees while climbing. [35] Because of this, placing an injured opossum in a confined space with its healthy counterparts is inadvisable. Virginia opossums are famous for entering a catatonic state when they are alarmed; this is commonly known as “going opossum”. [51], Like raccoons, opossums can be found in urban environments, where they eat pet food, rotten fruit, and human garbage. The Virginia opossum breeds in late January to early July, after which the female constructs a nest in the hollow of a tree or an abandoned burrow. [23] Insects such as grasshoppers, crickets, and beetles make up the bulk of animal foods. [42] The male's penis is also bifid, with two heads, and as is common in New World marsupials, the sperm pair up in the testes and only separate as they come close to the egg. Reproduction: In California, the Virginia opossum mates in January-February and June-July. However, given that age is positively correlated with body size for many marsupials it is unclear whether increased mating success in large individuals ultimately is an effect of body mass, age, or the interaction of these characteristics. Tissue samples were preserved in 95% ethanol in the field and then transferred to an ultra low freezer (−80 °C) for long-term storage. They are surprisingly resistant to rabies,[53] most likely because they have lower body temperatures than most placental mammals. Their coats are a dull grayish brown, other than on their faces, which are white. Because GERUD uses exclusion to estimate the number of male genotypes contributing to a given progeny array, estimates using this program are considered conservative and should never overestimate the number of sires for a litter (Jones 2001). They are solitary, nocturnal omnivores. If this does not work, the Virginia opossum is noted for feigning death in response to extreme fear. Only 13% of the basin was forested, with all contiguous forest tracts confined to major drainages where frequent flooding or locally steep topography made the land unsuitable for crop production. I ... MEMOIR ON THE REPRODUCTION OF THE OPOSSUM. Nonetheless, our finding that females commonly mate with multiple males suggests that sexual selection could be occurring within opossum populations at multiple biological scales: 1) direct competition among males for access to females and 2) competition among sperm from disparate males within the reproductive tract of females. [30] Plant foods are mainly eaten in late summer, autumn, and early winter. A detailed outline of the trapping methods are described elsewhere (Beasley and Rhodes 2008). Previous research indicates that competition among male opossums is extensive with male mating success presumably tied to body mass (Ryser 1992). Gestation is 12.5-13 days. Offspring <2″ in length were not sampled to minimize any impacts of tissue collection on future development. Possum days gone by. Virginia Opossum Reproduction. Likewise, male opossums have a bifurcated penis—a common trait among marsupials. The clearing of dense forests in these areas and further north by settlers allowed the opossum to move northward. Previous research on Virginia opossums is ambiguous with regards to the movement behavior of this species. Multiple paternity in a field population of a small carnivorous marsupial, the agile antechinus. Like most marsupials, opossums are very small when they are born - about the size of a navy bean. Nonetheless, many species of marsupials clearly exhibit female promiscuity and thus, alternative evolutionary benefits (e.g., increased litter sizes) or proximal behaviors (e.g., sexual coercion) likely exist for promiscuity to be maintained in this group. Opossums have long, hairless, prehensile tails, which can be used to grab branches and carry small objects. [39] Males extend their range in search of mates which puts them at greater risk of injury from motor vehicles and predators due to unknown territory. If you see a Virginia Opossum in your travels, it could well be on the hunt for a mate at this time of year. Our 1165-km2 study area was located in the upper Wabash River basin (UWB) in northcentral Indiana, USA. It is a solitary and nocturnal animal about the size of a domestic cat. The Virginia opossum does not hibernate, although it may remain sheltered during cold spells. These characteristics have been the subject of fables and discredited theories about conception of young opossums through the female's nose. This is illustrated in the pacing diagram, which explains why the left-fore and right-hind tracks are generally found together (and vice versa). The young opossums are incredibly small at birth, about the size of a honeybee, each weighing o… Finally, we used data on assigned paternity to make inferences regarding the movement behavior of this species in a highly fragmented agricultural landscape. This is the genesis of the term "playing possum", which means pretending to be dead or injured with intent to deceive. They also have hairless ears and a long, flat nose. We ran 100 000 simulations using 1 known parent (mother), assuming a 1% (observed) genotyping error rate, and assigned paternity at both 95% and 99% confidence levels (Marshall et al. 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