The Virginia opossum, often called a possum, is the only marsupial found north of Mexico in North America. Marsupials give birth to highly undeveloped, embryonic young after an extremely short gestation period. These premature newborns complete their development outside the womb, typically within a specialized pouch on the mother’s abdomen known as the marsupium. This reproductive strategy divides maternal care into distinct phases, starting in the pouch and ending when the young venture out.
Early Development: Life Inside the Pouch
Gestation lasts only 11 to 13 days. Newborns emerge in an almost embryonic state, appearing hairless, blind, and pink. They are exceptionally small, comparable in size to a honeybee or a dime, and weigh about 0.13 grams.
The mother provides minimal assistance, primarily licking a path through her fur to the pouch entrance. The newborns must then instinctively climb using their forelimbs to reach the marsupium. Inside the pouch, the young locate one of the mother’s teats, which typically number 13, and latch on firmly.
The teat swells inside the infant’s mouth, creating a secure attachment for continuous feeding and growth. The young remain confined within the pouch for the first 50 to 70 days of life. As they grow, their eyes begin to open around 55 to 70 days, and they develop fur, marking the end of this initial phase.
The Weaning Phase: Riding and Foraging
Once the young reach approximately 70 to 85 days old, they become too large for the pouch to contain them fully. They transition from continuous pouch residency to riding on the mother’s back, a behavior often referred to as “jockeying.” The young cling tightly to the mother’s fur, using their claws and prehensile tails for a secure grip as she moves.
This phase is a period of behavioral learning, where the young are exposed to the outside world under the mother’s protection. They observe the mother’s movements, learn safe routes, and begin recognizing food sources. Survival instincts, such as foraging patterns and predator avoidance, are imprinted during these rides.
Weaning, the transition from milk to solid foods, occurs concurrently with this riding phase. The young start incorporating solid food around 85 days old, with full weaning completed between 93 and 105 days of age. Even when not actively riding, the young rely on the mother for shelter and defense, returning to her side or den for safety. The mother maintains auditory contact using soft clicking sounds.
Timeline to Independence and Dispersal
Young opossums become independent between three and four months of age, or approximately 100 to 120 days old. By this time, they are fully weaned, have developed a dense coat of fur, and possess the motor skills necessary to navigate their environment alone. They are considered ready for release if they measure at least eight inches long from the nose to the base of the tail and weigh over 200 grams.
Dispersal is the final stage of maternal care, where the young move away from the mother’s territory to establish their own home ranges. This separation is permanent; once the young leave, there is no further parental guidance or interaction. The mother’s investment ends abruptly once they are capable of surviving on their own. This rapid transition to a solitary life is characteristic of the opossum’s strategy.