The Virginia opossum (Didelphis virginiana) is the sole native marsupial found in North America. Its reproductive strategy differs significantly from placental mammals, involving a very short gestation period followed by development within a specialized pouch. Understanding the duration of parental care provides clarity on their biology and eventual solitary life in the wild.
Early Development: Pouch Life and Back Riding
The reproductive cycle begins with an incredibly brief gestation of only 12 to 13 days. Newborn opossums, often referred to as joeys, are born in a highly premature, embryonic state, measuring about the size of a honeybee and weighing less than a dime. Immediately after birth, these tiny, undeveloped young use their strong forelimbs to crawl from the birth canal up the mother’s abdomen and into her external pouch, called the marsupium.
Once inside the pouch, the surviving young firmly latch onto one of the mother’s teats, which then swells inside their mouth. They remain attached for approximately 50 to 70 days. Around 55 to 70 days of age, the eyes of the young open, and they begin to develop a full coat of fur.
As the young grow larger, they eventually become too big to fit inside the pouch. They start to emerge and transition to riding on their mother’s back, clinging tightly to her fur with their feet and prehensile tails. This back-riding phase serves as a mobile nursery, allowing the mother to forage. The young will continue to return to the pouch to nurse even as they spend more time riding externally.
Defining the Timeline for Separation
The entire duration of dependency, from birth to full independence, spans about 90 to 120 days. The weaning process begins when the young are approximately 85 days old, as they start to sample solid foods. Full weaning typically occurs around the three-month mark, or 93 to 105 days after birth.
This process of separation is a gradual one, not a sudden event where the mother simply abandons the litter. While the young are riding on her back, they are actively learning survival skills, such as identifying food sources and recognizing predators. The mother will initiate the final separation by simply moving away from the young when they are ready to forage on their own.
By the time they are four to five months old, the young opossums have reached a size and developmental stage that requires independence. They possess the necessary strength, motor skills, and knowledge to survive independently. At this point, the mother’s reproductive hormones shift, and she ceases to provide care, compelling the opossums to disperse and begin their solitary lives.
Establishing Independent Territory
Following separation, the newly independent juveniles enter a phase of dispersal and solitary activity. Opossums are naturally solitary and do not typically seek out others except for mating. They are highly mobile and nocturnal, spending their days sleeping in temporary dens and their nights searching for food.
The young opossums move away from the immediate area of their birth den to establish their own home range. While they are not strictly territorial, they wander in search of resources, often traveling up to a mile from their natal site. This dispersal reduces competition for food and helps prevent inbreeding within the local population.
During this time, the skills learned while riding on the mother’s back are put into practice, refining their foraging techniques. They are generalist omnivores, capable of finding a diverse diet of insects, small vertebrates, fruits, and carrion. Successfully locating suitable shelter, such as hollow logs or abandoned burrows, and avoiding predators are the immediate challenges of their early young adult life.
Assessing Age and Need for Intervention
For a person who finds a young opossum alone, accurately assessing its independence level is the first step before intervening. Juvenile opossums that are independent will appear fully furred and look like miniature versions of the adults. The simplest and most reliable metric for the public is a measurement of the animal’s body size.
An opossum is independent and capable of surviving alone if it measures at least seven to eight inches long, measured from the tip of the nose to the base of the tail. This measurement deliberately excludes the tail. A self-sufficient juvenile typically weighs over 200 grams, or about 7.25 ounces.
If a young opossum is found that is smaller than this seven-to-eight-inch guideline, it is likely still dependent and requires intervention. In such cases, the best course of action is to immediately contact a licensed wildlife rehabilitator, rather than attempting to provide care. Improper feeding or housing can cause serious harm to a young marsupial, and licensed professionals possess the specialized knowledge to successfully raise them for eventual release.