Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"

Today we visit the Land Down Under for a look at a marsupial! And indeed, the largest extant marsupial. (I covered some of the enormous extinct ones such as Diprotodon in previous instalments.) This is the Red Kangaroo, Osphranter rufus. The average male stands about 1.5m/5' tall, but exceptionally they can stand 2.1m/7' tall and weigh 91 kg/200 lbs. The female is much smaller, from 18 to 40 kg. Also they are mostly not red, but more of a bluish or brownish grey. But females in the deserts are more similar to males. Red kangaroos occur over most of the interior of Australia, avoiding densely wooded terrain.

Desert Dwellers

Much of the interior of Australia where the red roos roam, is very dry, subdesert or desert. These regions experience extended drought periods, extreme heat in the summer, and in some of the more southern parts, cold nights. Red kangaroos have several adaptations to these challenging environments. They have very efficient kidneys that reabsorb water from their urine, which therefore is highly concentrated. They can derive almost all of the moisture they need, from vegetation, rarely needing to drink. They're able to consume salty plants or even vegetation that looks brown and dry, and extract moisture from these. They eat mostly grasses and forbs, many kinds of which are adapted to the harsh conditions of the drylands. Their dense fur insulates them against both heat and cold. In high temperatures, they pant, sweat, and lick their slender forelimbs so that the evaporating water can keep them cool. But they also avoid the extreme heat by being inactive, seeking out even low vegetation such as mulga bushes for shade. They reserve their activity for the cooler morning or evening hours, or even the nights. They're able to enter a state of torpor to conserve energy. They'll cover large distances to seek food in times of poor rainfall. When food is abundant, red kangaroos can congregate in groups of up to 1500.

Leaping Locomotion

The outstanding ability of this and other large kangaroos is their leaping! There are some other smaller critters that move in a similar style, such as the jerboas and similar mouse-like leapers, and the somewhat larger Springhare. But kangaroos are best at it, and of them all the red roo reigns supreme. The secret is its Achilles tendon, which is like a rubber band. It stretches as the ankle flexes, storing elastic energy that is then released as the ankle extends, meaning that very little actual exertion is necessary to keep up the leaping motion. But with a bit of exertion a kangaroo can attain some prodigious feats. The record for height is a kangaroo male clearing a woodpile of a tad over 3m/10' tall, and the distance record is a bit over 12 m/40'.

A more leisurely way of moving about, is a kind of walking where the kangaroo uses all four feet as well as its stout tail as a fifth limb. The forefeet move forward together, then the tail is propped against the ground so both hind limbs can move forward, and then the tail itself is moved forward while all four feet are on the ground.

Boxing Kangaroos

In the wild, male kangaroos 'box' and 'wrestle' as a kind of competition for status and access to females; it is more the younger males that do this. They will stand tall, facing each other, grappling with their long forelimbs to get their opponent off balance, or again use the tail as a prop and simultaneously kick at their opponent's belly with both hind legs. Male red kangaroos can develop impressive chest, shoulder and arm muscles.

At present, red kangaroos have no serious enemies except for humans. In addition to their speed, they have keen senses, with wide-set eyes giving them a great range of vision, and their large ears give them acute hearing, so as to always be aware of threats. In times past, they would perhaps have contended with a large, now extinct predator, the marsupial lion Thylacoleo (which I hope to feature here some time). Smaller individuals can still fall prey to dingoes or even wedge-tailed eagles. Kangaroos may flee to water to escape, where, if the predator pursues them, they may try to drown it by wresting it down under the water surface. But in water they may fall prey to the biggest of all Australian predators, the saltwater crocodile.

Roo Reproduction

Perhaps the most amazing thing about the red kangaroo, is the nature of its reproduction. First, adult females reach sexual maturity at about 18 to 30 months, and from then on, they are effectively perpetually pregnant! Of course, it starts with mating with a male. This can take about 25 minutes. Then, the pregnant female carries the unborn joey for only about 33 days. It emerges in very undeveloped condition, with mere stubs for hindlimbs, but strong forelimbs that it uses to crawl into the mother's pouch, where it attaches itself to a nipple and remains like that while the mother effectively pumps milk into it. The female then immediately comes into oestrus again! She will mate, and what happens now is that this new embryo does not develop further for a while – this is called embryonic diapause. The embryo is essentially put into suspended animation in one of the female's two wombs. This lasts until the joey she is carrying in her pouch, is old enough to leave, which is typically about 190 days. The joey will still return to the pouch from time to time to suckle while it learns to feed and to be independent. Now the new embryo starts its development again so that after another 33 days it can be born, attach to a nipple (a different one from that used by the older joey) and at the same time the female will release another egg which may be soon fertilized and then enter stasis again. So, a female red kangaroo can have three generations of children with her at the same time! A joey, out of the pouch; a newborn locked onto a nipple in her pouch; and an embryo in one of her wombs, soon to be born.

Status and Conservation

Red kangaroos benefited from a degree from the presence of humans; first of all from the elimination of the largest native Australian predators, even though those humans brought in dingoes, which also might prey on small kangaroos. But the roos also benefit from agriculture and the building of dams and the use of boreholes to bring water to the surface in ponds or watering holes. On the other hand, they are sometimes considered pests or nuisance animals, and persecuted. They may damage crops, and they're also notorious for damaging vehicles. Kangaroos leaping over roads occasionally land on cars, and a big roo might totally wreck a mid-sized car. They are also hunted for meat and skins, but for this, roo hunters need a special permit. At present, there are likely around 11 million red kangaroos in Australia, and they aren't likely to go extinct any time soon.

Willem

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