Opossums, the only marsupial native to North America, are common residents across Michigan. These adaptable creatures navigate diverse environments from woodlands to suburban areas. Their nocturnal habits and generally solitary nature mean their presence often goes unnoticed.
Breeding Season and Birth in Michigan
In Michigan, opossums begin their breeding season in late winter to early spring, from January or February through June. Females typically produce one to two litters per year. Their reproductive cycle has an exceptionally short gestation period, lasting only about 11 to 13 days.
Following this brief gestation, opossums give birth to a large number of underdeveloped young, often ranging from 6 to 9. At birth, these newborns, called joeys, are remarkably tiny, comparable in size to a honeybee, blind, and hairless. Their underdeveloped state requires further growth within the mother’s specialized pouch.
Development of Young Opossums
Immediately after birth, joeys instinctively crawl from the birth canal into their mother’s abdominal pouch, known as the marsupium. Inside, they locate and attach to a teat, which swells to secure their hold. They nurse continuously and develop within this protected environment.
Joeys remain within the pouch for about two to two and a half months, when their eyes open and fur develops. As they grow too large, around 75 to 85 days old, they emerge and often ride on their mother’s back. This “backpacking” phase allows them to learn survival skills like foraging and predator avoidance.
Weaning occurs around three months of age, though joeys may continue to ride on their mother’s back for several more weeks. By four and a half to five months old, reaching about 7 to 9 inches from nose to rump, young opossums are ready to become independent.
Encountering Young Opossums: What to Do
If a small opossum is found alone, assess the situation before intervening. Mother opossums do not return for joeys that have fallen off their backs. If a young opossum appears orphaned, injured, or is smaller than 7 inches from nose to the base of its tail, it likely requires assistance.
Contact a local wildlife rehabilitation center or animal control for guidance. While waiting for professional help, place the opossum in a warm, dark, quiet container, such as a shoebox with air holes. Do not offer food or water. Handle the animal with gloves for safety.