Opossum young are born underdeveloped and are known as joeys. These tiny young must complete their development inside a maternal pouch, where they attach to a nipple for constant nourishment. If a joey is found orphaned, understanding its developmental stage is paramount, as its feeding schedule is governed entirely by its size and maturity. Proper care requires immediate contact with a licensed wildlife rehabilitator, as improper feeding can lead to severe health issues.
Feeding Frequency by Developmental Stage
A joey’s weight is the most reliable measure for determining its feeding requirements, as this directly reflects its stage of development. Joeys attached to the mother’s nipple inside the pouch are receiving continuous nourishment for the first 50 to 70 days of their lives. Once orphaned, feeding frequency is intense and highly dependent on their size.
The smallest orphans, those weighing less than 50 grams, are extremely fragile and require feeding every 1.5 to 2 hours, day and night. This commitment is necessary because their tiny digestive systems process only small volumes of milk at a time. As the joey gains weight and stabilizes, reaching approximately 50 to 100 grams, the feeding intervals can be extended to every three hours. This reduction in frequency reflects a developing digestive tract that is starting to handle larger volumes.
Once the joey surpasses 100 grams, it enters the initial weaning stage, and the feeding frequency drops significantly. At this point, the joey is typically offered milk four to five times per day as it transitions to a more solid diet. These strict schedules are guidelines used by trained rehabilitators. The general public must never attempt to hand-feed an orphaned joey without professional guidance, due to the extreme risk of aspiration pneumonia from milk entering the lungs, which is often fatal.
Essential Diet and Nutritional Requirements
Opossum joeys have specific dietary needs that cannot be met by generic pet store formulas or household milk products. Mother’s milk is high in protein and fat, and low in lactose, which supports the joey’s growth. Feeding cow’s milk or kitten formula, for instance, is detrimental because it lacks the necessary nutritional balance and contains a different type of carbohydrate that can cause severe digestive distress.
Specialized milk replacers, such as Fox Valley Opossum Formula or Wombaroo Marsupial Milk Replacer, are formulated to mimic the natural milk composition. These species-specific products are high in fat and protein to support the rapid growth phase of the joey. Once the joey begins the transition phase, typically around 6 to 8 weeks old, a solid food diet is gradually introduced. This transition diet consists of a blended mixture of low-fat omnivore chow, mixed vegetables, and low-sugar fruits.
A major concern in opossum nutrition is the calcium-to-phosphorus ratio, which must be maintained at an ideal 1.5:1 balance. Without proper calcium supplementation in the diet, young opossums are highly susceptible to Metabolic Bone Disease. This condition causes bone deformities and fractures, and it is a common outcome when unauthorized individuals attempt improper feeding.
Criteria for Weaning and Self-Sufficiency
The transition from formula to a fully solid diet and eventual independence is a gradual process guided by the joey’s physical development. Weaning markers include the joey reaching a weight of 100 to 200 grams, at which point it should demonstrate the ability to lap milk from a shallow dish instead of being syringe-fed. The process is typically considered complete when the joey consistently eats solid food and reaches a weight between 300 and 400 grams, usually around 90 days of age.
After weaning, the focus shifts to preparing the young opossum for release into the wild. Rehabilitators monitor criteria to ensure the animal is self-sufficient and capable of survival. This includes reaching a minimum release weight, often over 400 to 500 grams, and measuring approximately 7 to 9 inches long from the nose to the base of the tail.
Release criteria center on the demonstration of natural behaviors, including climbing, foraging, and exhibiting a healthy fear of humans. The opossum must also be in peak physical condition, with strong muscle tone and a thick coat. Only when all markers of independence are met is the young opossum released into an appropriate natural habitat.