A baby possum, known as a joey, is born after a remarkably short gestation period, lasting only 11 to 13 days. Immediately after birth, the tiny joey must crawl into its mother’s pouch where it latches onto a nipple to complete its development. Determining the joey’s age is necessary because its survival hinges on whether it is still dependent on the mother or old enough to survive independently. Accurately estimating the age provides the context needed to decide if human intervention is required for the young marsupial’s well-being.
Visual Aging Indicators: Length and Weight
The age of a joey can be approximated using physical measurements, specifically its weight and body length (excluding the tail). A newborn joey is minuscule, weighing less than one gram and being roughly the size of a honeybee. By approximately two months old, the joey will have reached a weight range of 50 to 100 grams.
This two-month-old stage often corresponds to a body length of about three to four inches from the nose to the base of the tail. When joeys reach this size, they are typically becoming too large for the pouch and begin to emerge. Weight and length are quantifiable markers that wildlife rehabilitators use to determine the animal’s physical maturity and appropriate care category.
Developmental Milestones: Fur and Sensory Organs
For the first five to six weeks of life, a joey is essentially a “pinkie,” characterized by its pink skin and complete lack of fur. Around six weeks, a sparse, fuzzy layer of fur begins to emerge.
The development of the eyes is another milestone, as they remain sealed shut for the initial period of pouch life. A joey’s eyes will open between 55 and 70 days of age, or roughly eight to ten weeks. Once the eyes are open and the joey has a full, dark coat of fur, it is nearing the stage where it will leave the pouch permanently, marking a major shift in its dependency level.
Determining Independence and Weaning Age
Independence begins when the joey starts riding on its mother’s back rather than remaining fully enclosed in the pouch. This back-riding behavior usually starts around two months of age and continues for several weeks as the young possum is weaned. Weaning, the shift from mother’s milk to solid foods, typically occurs around three months of age.
A possum is considered fully independent and capable of surviving on its own in the wild when it meets specific size and weight criteria. This point is reached at around four to four and a half months old. The minimum safe size for independence is a body length of at least eight inches, measured from the tip of the nose to the base of the tail, and a minimum weight of 200 grams.
Immediate Action Steps Based on Estimated Age
If a joey is found hairless and with its eyes closed, it is a “pinkie” that requires immediate, specialized care from a licensed wildlife rehabilitator. Such young animals cannot regulate their own body temperature and have a very low survival rate outside of professional care.
If the possum has fur and its eyes are open but does not meet the 8-inch/200-gram threshold for independence, it is still a dependent juvenile. In this case, the animal should be contained safely in a dark, quiet, warm space, and a local wildlife rescue organization must be contacted immediately. A possum that meets or exceeds the eight-inch length and 200-gram weight requirement is considered independent and should be left alone, unless it is visibly injured or ill.