Opossums are unique marsupials found across North America, known for their distinctive appearance and nocturnal habits. As the continent’s only marsupial, they carry their young in a specialized pouch. This article explores their reproductive behaviors, particularly the number of young they produce and the factors influencing litter sizes.
Average Litter Size
Opossums give birth to a large number of young, though not all survive to maturity. While a female opossum can deliver anywhere from 4 to 25 babies in a single litter, the typical number that successfully make it into the pouch and begin nursing is usually between 6 and 9. A female generally possesses 13 nipples, meaning more young are often born than the mother has teats to support.
If more young are born than there are functional teats available, the excess will not survive. Only those that can attach to a teat in the pouch will continue to develop. The survival rate from birth to independence is relatively low, with only a small fraction of the initial litter reaching reproductive age.
Factors Affecting Litter Size
Several elements influence the number of young an opossum might have in a given litter. Environmental conditions play a role, with factors such as food availability directly impacting a female’s reproductive capacity. In environments where food is abundant, females are healthier and can support larger litters. Climate and habitat quality also contribute, as favorable conditions provide better resources for breeding.
Biological factors, including the mother’s age and overall health, also determine litter size. Younger or older females may have smaller litters compared to those in their prime reproductive years. Geographic location can also influence litter sizes; for example, opossums in some southern regions may have two or even three litters a year due to extended warm periods and consistent resource availability.
From Pouch to Independence
The journey of opossum young begins with their small size at birth. Born after a gestation period of only 11 to 13 days, each newborn is tiny, often no bigger than a honeybee or a grain of rice, weighing approximately 0.13 grams. These underdeveloped young, known as joeys, must immediately crawl from the birth canal into the mother’s pouch, where they instinctively attach to a teat.
The joeys remain securely fastened to a teat within the pouch for about 2 to 2.5 months, continuing their development and receiving nourishment. Their eyes open around 55 to 70 days of age. As they grow too large to fit entirely inside the pouch, they begin to emerge and often ride on the mother’s back, clinging to her fur. This “piggyback” phase is important for learning survival skills, and the young become fully independent around 4 to 5 months of age.