Opossum

cuteoposAbout
The Virginia opossum (Didelphis virginiana) is the northernmost North American marsupial, but its range in this province is limited to southern Ontario, where it is increasingly common.

Description
Adults range in size from less than 1 kg (2.2 lbs) to about 6 kg (13 lbs) depending on sex and time of year. Virginia opossums keep growing throughout their lives, resulting in considerable variation of weight and size. Males are larger and heavier than females. They have a pointed snout, dark eyes and darkly pigmented, naked ears. The feet are adapted for climbing, and all toes except the large toe of the hind foot have well-developed claws. The long tail is whitish except at the base, where it is black. The scaly and nearly naked tail is also partially prehensile, meaning that it can be used to anchor the opossum’s body by wrapping it around a branch. The colour of the fur is variable by region. The under-fur is usually white at the base and dark brown or black at the tips and is thicker in the northern population than the southern. The under-fur of the back is covered by long guard hairs. All white guard hairs (gray phase) are common in the northern populations, while white with black tip guard hairs (black phase) are seen in the southern populations. All opossums have white cheek hairs bordered above and behind by darker fur. The lower legs and feet are usually black.

Life History
Female opossums become sexually mature at six months, but few reproduce successfully during their first season. The breeding period generally extends from late January to early February in the northern populations and from late December to early January in the southern populations. The females are capable of having more than one litter in a year. The young are born in an embryonic state and spend the first two months in the female’s pouch. Litter sizes vary and depend on the number of functional nipples. Generally a female opossum has 13 nipples, which are arranged in a circle with one located in the centre, all within her pouch. Life expectancy is one to three years, although few opossums survive beyond their second year. Opossums are liable to be killed by parasites, exposure in winter, motor vehicles, and predators including hawks, owls, coyotes and foxes.

Habitat
Opossums in Ontario are at the northern extremity of their North American range. They can occupy a variety of habitats, including agricultural habitat and edges, woodlands and escarpments, but their preferred habitat is deciduous forests associated with wet areas such as streams, swamps and marshes.

Food and Feeding Behaviours
The opossum is classified as an omnivore. It eats a wide variety of foods, including both terrestrial and aquatic invertebrates. The opossum will also eat small vertebrates and fruit while it forages mostly on the ground.

Habits
Opossums are usually solitary animals, and are most active between dusk and dawn. Though they are mainly ground dwelling, they can climb trees and are strong swimmers. They are most active during the warmer months of the year, and rarely venture outside their dens when temperatures fall below -15°C (5°F). Opossums are not overly territorial, and their home ranges overlap, even during the breeding season. They are polygamous, and both males and females will mate with more than one partner in the same year. The females carry their young in a pouch until three to four months of age when the young are completed weaned.

Population Changes
Opossums are subject to a variety of parasites and to predation by a variety of species. Opossums are slow moving; in one study, 35% of deaths were due to motor vehicles. Because of the relatively low value of the fur, trapping in Ontario is not a major factor affecting populations.

Management
There are no quotas for the harvest of opossums in Ontario. The trapping season closely parallels the raccoon season, and opossums are often taken in trap sets for raccoon.

Trap Sets for Opossum
Secure all traps strongly enough to hold the largest potential catch. The trap sets described for raccoon, using 160 or 220 size killing trap (Conibear type) or similar killing traps, will be effective for opossum when set in locations where they are known to travel. Opossums can be attracted by a variety of baits, including meat and fruit. Where there are likely to be dogs, covering the trap with a tunnel made of brush will cause the dog to go around, while the opossum will readily enter.

Pelt Preparation for Opossum
Pelt preparation, which consists of skinning, fleshing and drying, begins at the trap site. There, and at each stage of the preparation process, care must be taken to ensure that the pelt will be presented to the buyer in excellent condition. Carefully prepared pelts bring higher prices.

Removing Opossums from Traps
When taking the opossum out of the trap, avoid removing any of the fur. Thorough waxing of the trap should prevent problems in removing opossums. Should they become frozen in the traps, allow them to thaw in a warm place before trying to remove them.

Skinning, Fleshing and Drying
Opossums are case-skinned, using the methods described for other case-skinned species. The first cut is from the ankle to the tail side of the anus on both legs, following the fur line and close to the anus. Then a straight cut is made from the centre of the underside of the tail, where the hair stops on the tail, to the first cuts. There is no fur on the tail, so it does not need to be pulled out. The next cut is where it is different from other animals. Go to the top of the pouch area and make an angled cut down to the first leg cuts on each side of the pouch. There is no usable fur on the pouch, and therefore it is then left on the carcass. This also creates a large inspection window, as opossum are marketed fur in. They are then case-skinned, making sure to cut the ears close to the skull and being careful around the eyes and nose. When fleshing opossums, a delicate touch is needed because they are very thin-skinned and it is not unusual to tear them in the leg area when first fleshing them. Opossum have a thin layer of fat next to the skin covered by a light membrane on top of the fat. Care must be taken to not pull the guard hairs through when fleshing since the roots are close to the leather. Once they are fleshed, they can be put up on small raccoon boards or large fisher boards to dry. Opossum dry fairly quickly because the leather is so thin.