In hopes of shedding more light on the complexity of these distinctive marsupials, here are just a few lesser-known facts about kangaroos.
1. Kangaroos Come in Many Shapes and Sizes
Kangaroos belong to the genus Macropus, which means “large foot.” Other members of that genus include several smaller but similar-looking species known as wallabies or wallaroos. That distinction is a bit arbitrary, however, since the animals we call kangaroos are simply the larger species in the Macropus genus. The smallest members of the genus are known as wallabies, while species of intermediate size are called wallaroos.
The term “kangaroo” is sometimes used broadly for any of these animals, although it’s generally reserved for the four largest species: red, eastern gray, western gray, and antilopine kangaroos. It’s also used for tree kangaroos, which belong to a different genus but are members of the wider taxonomic family known as macropods, which includes kangaroos, wallaroos, wallabies, tree kangaroos, pademelons, and quokkas. Outside the macropod family, tiny marsupials called rat kangaroos also bear a resemblance to their much larger relatives.
2. Kangaroos Are the Largest Marsupials on Earth
Kangaroos are the largest marsupials alive today, led by the red kangaroo, which can stand more than 5 feet (1.6 meters) tall — plus a 3-foot (1 m) tail — and weigh 180 pounds (82 kilograms). Eastern gray kangaroos can be even taller, with some adult males reaching nearly 7 feet (2.1 meters), but they’re also leaner, only weighing up to 120 pounds (54 kg).
3. They Can Use Their Tail as a Fifth Leg
When moving around smaller areas at a slower pace, kangaroos often incorporate their tail as a fifth leg. It may look awkward, but research on red kangaroos shows their big, muscular tails can provide as much propulsive force as their front and back legs combined.2
When a kangaroo needs to move more than about 15 feet (5 meters), however, it usually skips the tail and starts hopping.
4. A Group of Kangaroos Is Called a Mob
Kangaroos travel and feed in groups known as mobs, troops, or herds. A kangaroo mob may include a handful or several dozen individuals, often with loose ties that allow shifting membership among mobs. Males may fight over females in mating season by kicking, boxing, or even biting, but the group tends to be dominated by its largest male. Male kangaroos are known as bucks, boomers, or jacks, while females are called does, flyers, or jills.
5. They Eat Grass Like Cows, but Burp Less Methane
All kangaroos are herbivores, grazing mainly on grasses but also some moss, shrubs, and fungi. Similar to cattle and other ruminant animals, kangaroos sometimes regurgitate their food and chew it as cud before digesting it. This isn’t necessary for their digestion, though, and they only do it occasionally — maybe because it seems to cause them disᴛʀᴇss.
Kangaroos’ tube-shaped stomachs are very different from the four-chambered stomachs of ruminants. Cows infamously emit lots of methane — a potent greenhouse gas — as they breathe and burp, but despite similar diets, kangaroos only produce about 27% of the body mass-specific volume of methane that ruminants produce. Food moves more quickly through kangaroo stomachs, and research suggests kangaroos’ gut microbes are in a metabolic state more tuned for growth, or biomass production than for making methane.
6. Joeys Can Go Dormant Until the Pouch Is Vacant
If a joey is still in the pouch of a pregnant kangaroo, the younger sibling can enter a dormant state called embryonic diapause.
The gestation period for kangaroos is about five weeks, after which they usually give birth to a single baby, known as a joey. No larger than a grape, the newborn joey must use its forelimbs to crawl through its mother’s fur to her pouch. The joey will live in the pouch (called a marsupium) for the next several months as it continues to grow and develop.
A female kangaroo can become pregnant again while a joey is still in her pouch, in which case the younger joey enters a dormant state until the pouch is vacant. Once the older sibling leaves her pouch, the mother’s body sends hormonal signals to resume the younger joey’s development.
7. Some Kangaroo May Sacrifice Joeys to Predators
Fighting back against predators may be less realistic for smaller kangaroos, and for other macropods like wallabies, wallaroos, and quokkas. In some cases, a mother macropod who’s being chased by a predator has been known to drop the joey from her pouch and continue to flee.
As one study found, female quokkas caught in wire ᴛʀᴀᴘs tried to escape when they saw a human approaching, and in that commotion, their joey often fell from the pouch.4 That might have happened inadvertently during the mothers’ escape attempts, the researchers wrote, but “considering the muscular control that female quokkas have over the pouch opening … it seems likely that this is a behavioral response rather than accidental.” (The researchers returned these joeys to their mothers’ pouches.)
Other macropods have similar tendencies: Gray kangaroos sometimes expel their joeys when pursued by foxes, for example, and swamp wallabies do the same with dingoes. A predator would likely stop for the easy meal, giving the mother time to escape. This might sound unthinkable to humans, but it could be an adaptive survival strategy for some macropods, the researchers suggest. Kangaroo mothers can reproduce far more quickly than humans can, and when the life of a proven mother is at sᴛᴀᴋᴇ, sacrificing one joey might be ʜᴏʀʀɪʙʟy sensible, at least by her species’ standards.
8. They Sometimes ᴅʀᴏᴡɴ Their Enemies
Kangaroos don’t have a lot of natural predators in Australia, especially now that large carnivores like thylacines and marsupial lions are ᴇxᴛɪɴᴄᴛ. A few animals are known to prey on kangaroos, however, typically targeting joeys or adults from smaller species. These predators include dingoes as well as introduced species such as red foxes, dogs, and feral cats.
When a kangaroo does find itself pursued by a predator, it often flees toward water. This can just be an escape strategy, since kangaroos are surprisingly good swimmers (again, thanks to that massive tail). But in some cases, the prey might be leading its pursuer into a ᴛʀᴀᴘ. Once a kangaroo is chest-deep in the water, it will sometimes turn around and confront the predator, grabbing it with its forelimbs and attempting to ᴅʀᴏᴡɴ it.
9. Most Kangaroos Are Left-Handed
Humans and some other primates exhibit “handedness,” or the tendency to use one hand more naturally than the other. Scientists once thought this was a unique feature of primate evolution, but more recent research suggests handedness is also common in kangaroos.1
Based on research with red kangaroos, eastern grays, and red-necked wallabies, researchers have found the animals are primarily left-handed, using that hand for tasks such as grooming and eating about 95% of the time. Their hands also seem to be specialized for different types of work, with kangaroos typically using their left hand for precision and their right for strength. This challenges the idea that handedness is unique to primates, researchers say, noting it may be an adaptation to bipedalism.
10. Some Kangaroos Can Hop 25 Feet
Hopping is an energy-efficient way for kangaroos to move, helping them cover large distances in arid Australia as they search for food. They usually travel at moderate speeds, but they are capable of sprinting when necessary. A red kangaroo can hop at 35 mph (56 kph), leap about 6 feet (1.8 m) off the ground, and cover 25 feet (8 m) in a single bound.