Animal Bytes: Kangaroo and Wallaby

Range: Australia and New Guinea Habitat: found in every habitat in Australia, and in wet forests in New Guinea

By any other name would smell as sweet

The word "kangaroo" often brings to mind a picture of a big, bounding critter with long ears and a baby, or joey, peeking out of its mother's pouch. Maybe you envision Kanga and Roo from A. A. Milne's Winnie the Pooh books, or H. A. Rey's Katy No-Pocket from the story of the same name? Either way, kangaroos are perhaps Australia's best-known animal and are found in stories, movies, and even as sports team mascots the world over!

Macro-what?!

The kangaroo's family name, Macropodidae, means "big feet," a great description for kangaroos and their relatives! Kangaroos, wallabies, wallaroos, quokkas, pademelons, potoroos, rat-kangaroos, honey possums, and tree kangaroos are all macropods. Confused about the difference between kangaroos, wallaroos, and wallabies? That's understandable! There are more than 50 species of these marsupials, and they vary in size from critters you could hold in your hands to the giant red kangaroos Macropus rufus that stand as tall as an adult person.

The main difference between a kangaroo and all the others is size-the six largest species are referred to as kangaroos-but otherwise, they are quite similar. In most species, the hind legs and feet are much larger and more powerful than the forelimbs. Their tails are long, muscular, and thick at the base, helping the animal balance and turn during hopping and providing support when it rests.

Home, sweet pouch

Female kangaroos, called does, and their relatives give birth to tiny, underdeveloped young that are then carried in a special pouch, called a marsupium, on the doe's body. Inside the pouch, the joey attaches to a nipple and nurses for several months before venturing out into the world. Joeys often peek their heads out of the pouch to have a look around weeks before they head out on their own.

Do the joeys eliminate (pee and poop) in the pouch? Yes, indeed! When they are very small they don't produce much, and when they get bigger, some is absorbed through the pouch lining. It can get kind of smelly, though, so the mothers clean out their pouches from time to time.

Have to have a habitat

Red kangaroos and gray kangaroos Macropus giganteus and Macropus fuliginosus are found in savannas and open woodlands. Tiny short-nosed rat-kangaroos Bettongia sp., or bettongs, live in burrows in arid scrubland. Rock wallabies Petrogale sp. live on almost vertical rock walls in the southern desert. Tree kangaroos Dendrolagus sp., as you might guess, are found high in the rain forest canopy, while musky rat-kangaroos Hypsiprymnodon moschatus scamper through the dense, wet understory below. Red-necked wallabies Macropus rufogriseus live in many habitats, including the icy peaks of Tasmania's mountains, and the quokka Setonix brachyurus is found only on two windblown islands off the southwestern Australia coast. The three largest species of kangaroos are so adaptable that they are often found living in public parks, suburban gardens, and even on golf courses!

Mob scene

A group of kangaroos is called a mob, a troop, or a herd. They are very social animals. Think of a kangaroo's famous jabbing and boxing as macropod sign language. Behaviorists who study kangaroos say the jab is just one part of a whole vocabulary of glances, hisses, avoidance hops, kicks, punches, gentle touches, and grooming. Recently, behaviorists have discovered that the steps kangaroos take to get to know one another mirror the development of friendship in baboons!

When a kangaroo senses danger, it alerts its fellows by thumping its feet loudly on the ground! They can also communicate with each other by grunting, coughing, or hissing. A doe may make a clicking or clucking sound to call her young.

Greens are good

Kangaroos are herbivores, eating a wide range of plants. In fact, large kangaroos are the Australian equivalent of bison, deer, and cattle. All macropods have a chambered stomach that works much like those belonging to ruminants like goats and sheep. They can bring the vegetation they've recently swallowed back up from one chamber, chew it as cud, and then swallow it again for final digestion. Larger kangaroos tend to feed in mobs, though the group size depends on the amount and quality of food that is available.

At the San Diego Zoo and the San Diego Zoo Safari Park, the tree kangaroos and wallabies are fed herbivore pellets and leaf eater biscuits, leafy greens such as romaine lettuce, spinach, or kale, browse material such as ficus, hibiscus, or eugenia, and a half of a banana. Carrots, yams, papayas, and mangoes are used as treats or for training purposes.

Mysterious mammal movement

The kangaroo's muscular design lets it move in a way that is unique to macropods, called saltation. This means that they hop, both feet pushing off the ground at the same time. The larger kangaroos can cover over 15 feet (7 meters) per hop when cruising at top speed and have been clocked at more than 30 miles per hour (48 kilometers per hour) in short bursts!

Like a perpetual motion machine, a hopping kangaroo is able to keep moving without expending much energy. In fact, kangaroos actually burn less energy the faster they hop-at least up to their cruising speed of 20 miles per hour (32 kilometers per hour)! In addition to powerful leg muscles, kangaroos have a huge set of tendons in their tails that attach to their hipbones. The combination of these muscles and tendons working together helps the kangaroo move efficiently. Wallabies, while smaller in stature, are built and hop in a similar manner.

The big guys

The best-known macropods are the three widespread and common species of large kangaroos. The largest is the red kangaroo, which is found most often on the open plains of inland Australia and can live on very little water. Maroon with white faces and bellies, males are often referred to as red flyers. This species can be over 6 feet (1.8 meters) tall and weigh up to 200 pounds (90 kilograms)! Females, sometimes called blue flyers, are bluish gray and are smaller and faster than the males, reaching speeds of up to 30 miles per hour (48 kilometers per hour). Red kangaroos can, in an emergency, leap across the outback in 10-foot-high (3-meter-high) and 39-foot-long (12-meter-long) bounds-talk about a spring in your step!

The slightly smaller gray kangaroos, which need more drinking water than reds, usually inhabit woodlands, though they graze in grassy meadows at night. Those living in the eastern coastal regions have long, silver gray hair while those found inland have short, dark gray hair.

Smaller 'roos

All three of the large kangaroo species are closely related to the smaller wallabies and wallaroos that thrive in habitats ranging from wet forests to arid grasslands. There are brush, scrub, swamp, forest, and rock wallabies, which should give some clue as to the vastly different habitats these creatures call their own. Their smaller size lets them fill smaller, more varied niches than their larger cousins, but all are herbivores.

Up a tree

The typical kangaroo design of large, muscular hind legs and smaller forelimbs is nearly reversed in tree kangaroos, since they are climbers rather than hoppers and they have long, flexible tails that help with balance. Most tree kangaroos are found in the rain forest canopies of New Guinea, while two species are native to Australia. Like their ground-dwelling relatives, tree 'roos are herbivores and will leave their trees at night to eat vegetation and grubs. The major threats to endangered tree kangaroos are loss of habitat, being struck by cars, and being killed by dogs and/or dingoes.

Lost and found

In 1965, workers on Kawau Island (near Auckland, New Zealand) were attempting to reduce a population of tammar wallabies Macropus eugenii that had been introduced to the island years earlier and were now overrunning the place. They were astonished to discover that some of them were not tammar wallabies at all but a miraculously surviving population of parma wallabies Macropus parma, a species thought extinct since before the turn of the 20th century! The tammar wallaby reduction effort was halted while the parma wallabies were caught and sent to managed breeding facilities in Australia and around the world in the hope that they would reproduce and could eventually be reintroduced to their native habitat.

The renewed interest in the parma wallaby produced another surprise: a few years later, a small population was discovered in the forests of New South Wales in Australia! Further research proved that the parma wallaby was alive and well, and though not common, they could be found in forests areas there.