The Virginia opossum (Didelphis virginiana) is North America’s only native marsupial. Its reproductive strategy differs greatly from placental mammals, focusing on a brief internal development period followed by an extended infancy in a specialized pouch. Understanding when opossums reproduce and how their young develop provides insight into their life cycle.
The Opossum Breeding Calendar
The timing for opossum reproduction is linked to geographic location, but the breeding season generally spans from late winter through summer. In southern regions, mating can begin in January and continue until September. Northern populations have a slightly shorter season, typically running from February to September.
This extended period allows females to produce multiple litters annually. Most females successfully raise two litters, though three may occur in favorable conditions. The most intensive period for births occurs between February and June.
The male opossum initiates mating using distinct clicking sounds to attract a female. Females are receptive for only a short window; their estrus cycle lasts approximately 28 days, but they are only in heat for about 36 hours.
From Gestation to the Pouch
The opossum reproductive process features a short gestation period, a hallmark of marsupials. Following conception, the young are born just 11 to 13 days later. At this point, the newborns are in an embryonic state, hairless, blind, and about the size of a honeybee.
While the average litter size is between six and nine, a female can give birth to over 20 infants. The undeveloped young must undertake an instinctive journey from the birth canal up the mother’s fur and into her pouch, known as the marsupium.
Inside the pouch, the surviving young must immediately locate and latch onto one of the mother’s teats. The female possesses a limited number of teats, usually around 13, which creates intense competition. Any infant that fails to secure a teat will not survive.
Development and Independence
The young opossums remain attached to the teat within the pouch for the first two months. The teat swells inside the infant’s mouth, securing the attachment and providing nourishment. Around 50 to 70 days after birth, their eyes open, and they become too large for the pouch.
The young begin to venture out, often clinging tightly to the mother’s back. For the next month, the mother carries the litter as she forages, providing protection and teaching survival skills. They continue to return to the pouch to nurse until they are approximately three months old, when they are fully weaned.
By the age of about four months, the young have reached a sufficient size to survive on their own. They are considered fully independent when they measure between seven and ten inches long from the nose to the base of the tail. They then disperse to establish their own territories.
Encountering Orphaned or Injured Young
People frequently encounter juvenile opossums during the summer and fall when they begin traveling independently. A mother opossum does not return for a young one that has fallen off her back. Intervention is necessary only if an opossum is truly orphaned or injured.
A guideline for intervention is size: any opossum found alone that is less than seven inches in length (measured from the nose to the base of the tail) is too young to be independent and should be considered an orphan. Intervention is also necessary if an opossum of any age is visibly injured, bleeding, or has been caught by a domestic animal.
If an opossum meets the criteria for intervention, keep it warm and secure in a dark, quiet container. Providing food or water is strongly discouraged, as improper feeding can cause harm. Contact a licensed local wildlife rehabilitator, who is trained to provide the specialized care these marsupials require.