Once the young are big enough to come out of the pouch, they will climb onto his or her mother’s back and cling to her fur as they move from place to place. On occasion, a baby will fall off. Because the mother usually has many babies on her back, she may not notice that one had fallen off and will just keep moving on her way.
If the mother opossum is nowhere to be seen, it is unlikely that she will return for the lost baby, and reuniting will not work.
A young opossum is able to be on his own once he reaches 7” in body length from the tip of the nose to the base of the tail. If the young opossum is of this size, it is best just left alone unless he is injured.
Mother opossums are often hit on roadways, especially during baby season as they are burdened with the extra weight of their young preventing them from moving very quickly. Because the babies are so well protected in the mother’s pouch, it is not uncommon for the babies to survive, even if the mother did not. If it safe for you to do so, you may check the pouches of opossums killed on the roadways to see if she has any surviving offspring. Young babies will still be in the pouch, and older babies may be found in the area around or still clinging to the deceased mother. These babies can be collected and taken to your local wildlife rehabilitator.