The journey of a baby kangaroo, known as a joey, from birth to independence involves a specialized diet. As marsupials, kangaroos give birth to underdeveloped young that must complete early growth inside the mother’s pouch. This unique biological process creates complex nutritional requirements, as the mother’s body adapts to provide precise sustenance for different developmental stages. The joey’s diet shifts dramatically through three distinct phases: exclusive milk, dual-diet weaning, and adult grazing.
The Initial Milk Diet in the Pouch
A newborn joey is tiny, blind, and hairless, about the size of a jellybean. After a gestation of only about a month, it crawls unaided into the mother’s pouch. Upon arrival, the joey permanently attaches itself to one of the four teats, which then swells to hold the young in place for several months. For this initial phase, the joey is entirely dependent on this single source of nutrition for survival and growth.
The mother does not actively nurse the joey; instead, she uses specialized muscles to pump milk directly into the joey’s mouth. This early milk is watery and rich in simple carbohydrates for quick energy, along with high levels of protein to fuel rapid development. For large species like the Red Kangaroo, the joey remains exclusively attached to the teat for around eight months.
The Phenomenon of Sequential Lactation
The most extraordinary aspect of the kangaroo diet is sequential lactation. This occurs when the mother has a newborn attached to one teat and an older, pouch-emerged joey suckling from another. The mother possesses the biological ability to produce two entirely different types of milk simultaneously from two separate mammary glands to match the specific needs of each young.
The milk composition is carefully regulated by the mother’s body, changing constantly in response to the age and developmental stage of the joey attached to that specific nipple. The milk for the older joey transitions to a higher concentration of solids, increasing in fat and protein content to support its size and independence. Meanwhile, the milk produced for the newborn remains watery and carbohydrate-rich, ensuring both young thrive through precise nutritional specialization.
Transitioning to Solid Foods
The transition to solid food begins when the joey is well-furred and starts to poke its head out of the pouch, typically around six to nine months, depending on the species. The joey’s first solid food is often nibbling on grass and other vegetation the mother is eating while she grazes. This tentative exploration marks the beginning of the weaning phase, though milk remains a substantial part of the diet.
A significant event in this transition is the ingestion of a specialized form of the mother’s feces, sometimes called “pap.” This is not for nutrition but serves as a biological inoculation to establish essential gut flora. Kangaroos are herbivores and require a specific community of microbes to break down the tough cellulose in grasses. By consuming the mother’s intestinal matter, the joey acquires the necessary bacteria to begin digesting plant material, preparing its gut for grazing.
The joey continues to use the pouch and suckle until it is fully weaned, a period that can last up to 18 months for species like the Eastern Grey Kangaroo. During this dual-diet phase, the mother’s specialized milk provides sustained energy and protein, bridging the gap until the joey’s digestive system can fully process adult food.
The Adult Kangaroo Diet
Once fully weaned, the kangaroo becomes an independent herbivore, relying solely on plant matter for sustenance. Kangaroos are primarily grazers, meaning their diet is dominated by native grasses. They possess a chambered stomach, similar to ruminants, which allows them to effectively break down and absorb nutrients from fibrous plant material.
The specific diet varies between species and is influenced by the local environment and seasonal availability. While grasses are the main food source, kangaroos also consume leafy branches, shrubs, and sometimes fungi. Their flexible feeding habits allow them to adapt their diet to survive in the often-harsh Australian landscape.