The red kangaroo is most active from late afternoon to early morning, resting in the shade during the heat of the day (2) (4), and sometimes licking the forearms to cool the body through evaporation (7). The powerful, enlarged hindquarters enable the familiar leaping mode of locomotion, and the red kangaroo may be able to reach top speeds of up to 64 kilometres per hour (4), covering up to 9 metres with each leap (2). The diet consists of grasses, herbs and shrubs, with a preference for green feed, such as newly sprouted grasses (1) (4) (5), and the red kangaroo may travel long distances in response to food availability (1) (2) (5). This species usually lives alone or in small groups of up to ten, comprising mainly females with young, plus one or more males. However, larger, loose groups, or ‘mobs’, may gather to feed or drink (2) (4) (5).
The red kangaroo is an opportunistic breeder, able to breed year-round when conditions are favourable, but often ceasing reproduction during drought (2) (5) (8). The males engage in ritualised ‘boxing’ in order to gain temporary control of females in oestrus, wrestling with the forelimbs around the opponent’s shoulders and kicking with the powerful hindlimbs (2) (4) (5) (6). The female usually gives birth to a single young, after a gestation period of around 32 to 34 days (2) (9). At birth, the newborn weighs a mere 0.75 grams, and takes about three minutes to make its way, unaided, through the female’s fur and into the pouch, where it attaches to a teat for the next 70 days of development (2) (6) (9). The young, or joey, first protrudes its head from the pouch at 150 days, emerging for short periods at 190 days, and permanently leaving the pouch at 235 to 240 days (2) (9), although still suckling for another 3 to 4 months (4). Sexual maturity is reached at around 15 to 24 months, and lifespan may be up to 27 years (2) (4).
The female red kangaroo is able to become pregnant again within days of giving birth. However, in a process known as embryonic diapause, the new embryo remains dormant until the first young is about 200 days old, or sooner if the first young is lost. The embryo then resumes development and is born around 31 days later, within about a day of the first young permanently leaving the pouch. The female is then able to mate again (2) (4) (5) (6) (9). As a result of this process, when conditions are good the female can simultaneously support a suckling young outside the pouch, a suckling young within the pouch, and a dormant or developing embryo, and any young lost during drought can quickly be replaced when conditions improve (2) (5) (6).