Red Kangaroo

The red kangaroo is the biggest marsupial on Earth and the animal on Australia’s coat of arms. It is a specialist in one of the hardest environments there is — the hot, unpredictable interior of an entire continent — and it gets around by bouncing.

Overview

Red kangaroos live across the dry heart of mainland Australia, in country that might get 200 mm of rain in a good year and almost none in a bad one. They are grazers of open grassland and shrubland, most active at dawn, dusk, and night, and they rest in the shade through the worst of the day.

Physical characteristics

A large male stands up to 1.8 m, weighs 90 kg, and is powerfully muscled across the chest and forearms; females are much smaller and, despite the species’ name, often blue-grey rather than red (hence the nickname “blue flyer”). The body plan is unmistakable: small forelimbs, enormous hind legs, and a thick, muscular tail up to a metre long.

That tail is not just for balance. When a kangaroo walks slowly it plants the tail like a third leg and swings both hind feet forward together, and in a fast chase it acts as a counterweight and rudder.

Hopping

Kangaroos are the only large animals that hop as their main gait, and it is a genuinely superior way to travel fast in the outback. Long, springy tendons in the ankles and feet store energy on landing and release it on take-off, like a pogo stick. The result is that a kangaroo’s energy cost stays flat or even falls as it speeds up between about 15 and 40 km/h, letting it cover huge distances between scattered food and water at little cost. Breathing is also linked to the bounce — the guts act as a piston that helps pump air in and out — so hopping is almost free.

Coping with drought

Red kangaroos are built to ride out dry years. They can go long periods without drinking, getting moisture from plants; they lick their forearms, where a network of blood vessels sits near the surface, to cool down by evaporation; and their reproduction is tied tightly to rainfall. In a severe drought females simply stop breeding, and existing pregnancies and pouch young may be lost, so the population contracts. When rain returns, the paused embryos develop and numbers rebound within a few years.

Reproduction and the pouch

A newborn red kangaroo is the size of a jellybean — blind, pink, and barely formed. It crawls unaided through its mother’s fur into the pouch, latches onto a teat, and finishes developing there for about eight months. Even after it starts leaving the pouch, the “joey at foot” keeps returning to nurse for several more months.

Thanks to embryonic diapause and the ability to produce two different kinds of milk from different teats at once, a female can support offspring at three life stages simultaneously — a reproductive strategy tuned to boom-and-bust conditions.

People and kangaroos

Red kangaroos are abundant and secure. They are one of very few large native mammals worldwide whose range and numbers have arguably increased since European settlement, helped by artificial water points and the suppression of dingoes on grazing land. They are managed as a harvested species, with annual quotas set from aerial surveys, and remain a national symbol and a fixture of the outback landscape.