Virginia Opossum
Order Didelphimoria : Family Didelphidae : Didelphis virginiana Kerr

Description. A mammal about the size of a terrier dog, with long, scaly, prehensile tail; short, black, leathery ears; long, slender snout; five toes on each foot, the "big toe" on hind foot lacking a claw, thumblike and opposable; soles naked; pouch for young developed during breeding season on abdomen of female; pelage of long guard hairs and short soft underfur; two color phases — (1) grayish and (2) blackish; basal fourth or more of tail black, terminal section whitish; legs and feet blackish, toes often white or whitish. Dental formula: I 5/4, C 1/1, Pm 3/3, M 4/4 X 2 = 50. External measurements of males average: total length, 782 mm; tail, 324 mm; hind foot, 66 mm; of females, 710-320-63. Weight, 1.8-4.5 kg; males are usually larger and heavier than females.

Distribution in Texas. Occurs statewide except for xeric areas of the Trans-Pecos and Llano Estacado of the Panhandle.

Habits. Opossums are primarily inhabitants of deciduous woodlands but are often found in prairies, marshes, and farmlands. In the western part of their native range they generally keep to the woody vegetation along streams and rivers, a habit which permits them to penetrate the otherwise treeless grasslands and deserts of west Texas.

Hollow trees and logs are preferred sites, but opossums will den in woodpiles, rock piles, crevices in cliffs, under buildings, in attics, and in underground burrows. Since they are not adept at digging burrows for themselves they make use of those excavated by other mammals.

Movements of opossums monitored in East Texas showed that these animals typically frequent a home range approximately 4.6 ha in size, although the minimum size of home ranges may vary from 0.12 ha to 23.4 ha. Home ranges tend to overlap considerably. In East Texas woodland habitat the density of opossums is about one opossum every 1.6 ha while in sandy, coastal parts of the state the density is about one opossum every 6 ha.

The opossum is more or less solitary and strictly nocturnal, venturing forth to feed shortly after dark. It feeds on a variety of foods, including rats, mice, young rabbits, birds, insects, crustaceans, frogs, fruits, and vegetables. Analyses of six stomachs from winter-trapped opossums in Texas revealed that the following foods (expressed in percentages) had been eaten: insects (grasshoppers, crickets, beetles, bugs, ants), 62.8; mammals (cottontails), 19.5; birds (sparrow family), 15.5; reptiles (lizards and snakes), 1.0; mollusks (snails), 1.0; crustacea (crayfish), 0.2. In June the food for four opossums was about the same except that fruits and berries were added and birds were lacking.

Their mating season extends from January or February to June or July. Females, which are in heat for about 30 days, breed the first season following birth. The mating period is not longer than 36 hours and terminates with copulation, which is done in a manner similar to dogs. Young opossums have been observed as early as January 24 and as late as August 15. Usually two litters are produced — in February and June. The young, five to 21 in number, are born after a gestation of 11-12 days and each weighs about 3 grains (1/5 of a gram; 1/2,380 of a pound)! Blind, nearly helpless, hardly larger than honey bees, and embryonic in appearance they crawl unaided into the abdominal pouch of the mother, each attaching itself to a nipple. Shortly after a young one begins to nurse, the nipple swells and completely fills its mouth, thereby firmly attaching it to its mother. It remains attached until it is about 7 weeks of age, at which time it has grown large enough to detach itself. This peculiar adaptation compensates in part for the brief period of uterine development and assumes part of the function performed by the placenta in higher mammals. Since the number of teats is seldom more than 13, young born in excess of that number are doomed to die.

Mortality is high during the first year of life, and population turnover is relatively rapid. Known predators include foxes, coyotes, horned owls, and barred owls. Opossums are commonly seen killed on highways. The normal lifespan may be as low as 2 years.

The opossum is the second most commonly harvested furbearing animal in Texas, but the value of its pelt is low. During the period 1976 to 1982 the average value of an opossum pelt was only $1.83. Many trappers do not consider opossums worth "skinning out." Their fur is used primarily for trim on less expensive coats and hats.

Photo credits: John L. Tveten (top), John Wood (bottom).