Eastern grey kangaroo with joey. ©Getty Images

Eastern grey kangaroo with joey. ©Getty Images

The name 'kangaroo'

While he was mapping the east coast of Australia,  Captain James Cook's ship, the Endeavour, ran aground near what is now Cooktown.  When exploring the area,  he saw grey kangaroos, which in the language of the Aboriginal peoples of that area is 'gangurru'.  He interpreted that as 'kangaroo'.  

What are kangaroos?

Kangaroos belong to a group of marsupials called macropods, which means 'great footed animals'.  Marsupials are born after a very short pregnancy and are very tiny and undeveloped when they are born, so they complete their development inside a pouch on the outside of their mother's belly.  

Red kangaroo bounding along in Australia's 'red centre'.

Red kangaroo bounding along in Australia's 'red centre'.

Macropods have strong back legs with long feet. They hop on their back legs when travelling, using the muscular tail as a balance. Hopping in this way is an energy-efficient way of travelling long distances.  Their front legs move together, rather than independently of each other. Their front legs are small.  When moving slowly, usually as they graze or to change position, the tail and front legs prop up the animal, and the back legs move forward.. this is called 'crawl walking'.  The tail works rather like another leg when the animal is moving slowly in this way.

There are over 60 different species (kinds) of  macropods. The family includes kangaroos, wallabies, wallaroos, pademelons, and tree kangaroos. Close relations are the potoroo, bettong and rat-kangaroo.

Fun facts

  • Kangaroos are not able to move backwards very easily, which is why it is part of the Australian crest, or national emblem, along with the emu which has similar difficulty. Together they represent a country that is moving forward.
  • A male kangaroo is called a boomer or buck, a female is called a flyer or jill, and a young kangaroo is called a joey. 
  • Australian animals were completely strange to the Europeans who first came. When early explorers saw kangaroos, they described them as having heads like deer but without antlers, that could stand up as tall as men but that hopped like frogs. Female kangaroos with a joey's head peeping out of the pouch confused them, as they thought they were two-headed animals!

Different kinds of kangaroos

The red kangaroo is the biggest of all the marsupials.  A male can be 1.5 metres long with a 1 metre long tail. It can weigh 85 kilograms. Females are smaller. They  can travel as much as 9 metres in a single bound when at full speed.  Males are a reddish colour, but the females are a grey colour. Red kangaroos are found mostly in the centre of Australia, where it is hot and there is little rainfall. It is flat, open country with scattered trees.

The grey kangaroo is found along most of the eastern half of Australia. Grey kangaroos are almost as big as red kangaroos, but are a greyish - brown colour.  There are Eastern Grey and Western Grey kangaroos.

Habitat and Distribution (where they are found)

Different types of kangaroo live throughout Australia, including the island state of Tasmania and offshore islands, in a variety of habitats from tropical rainforests, beaches, deserts and cold areas.

Behaviours and Social Organisation

A mob of grey kangaroos. ©Getty Images

A mob of grey kangaroos. ©Getty Images

Kangaroos are good swimmers, and will sometimes escape a threat by going into water if it is nearby. They feed in the late afternoon and early morning,  spending  the day resting in shade.  In hot weather they scrape the ground with their front paws and lie on the cooler earth they have exposed.  Kangaroos do not sweat, so in the heat they lick their front paws and rub the moisture onto their chests so the breeze will cool them down. 

Kangaroos live in groups of ten or more called mobs.  Mobs can number over 50.  Living in a group means there is protection for the weaker members. There are always some of the mob looking up so danger can be spotted quickly. The kangaroo has few natural predators. The thylacine was its main predator, but is now extinct.  Dingoes are a threat, as are introduced species such as foxes and feral dogs or cats.  A kangaroo's first defence is its speed, reaching about 50kph.  However, if cornered, unable to flee,  its back legs can deliver  powerful and dangerous kicks, while its front paws can tear at an opponent's chest and stomach in a sort of boxing movement.  Kangaroos rarely attack unprovoked, but all animals have instinctive defence actions if they are threatened.

Diet

Kangaroos feed from late afternoon into the night and again early morning, on grass and other low growing plants. They  drink water when they find it, but can go for long periods of time without drinking because they get moisture from their food.

Life Cycle

A female kangaroo preparing to give birth. In that position, the tiny joey is born onto the tail.

A female kangaroo preparing to give birth. In that position, the tiny joey is born onto the tail.

Kangaroos weigh less than 2 grams when they are born. To give birth, the female kangaroo sits against a tree or stump, with her tail in front of her. The tiny baby, called a joey,  lands on the tail when it is born, and then climbs up its mother's belly and into her pouch.  If it falls onto the ground, it would not survive  -  the mother can't touch it because it is so tiny, the size of a small jelly bean, that she would kill it by trying to move it. She licks a path in her fur for it to travel along up to the opening of the pouch.

A kangaroo inside the pouch 12 weeks after birth. ©Getty Images

A kangaroo inside the pouch 12 weeks after birth. ©Getty Images

Feeeding the joey

There are four teats inside the pouch, and the joey grabs onto one of them and remains attached to it for about nine months, not letting go. Milk is automatically fed to the joey at regular periods of time, and the milk changes according to the joey's needs as it grows until it no longer needs milk. As it grows bigger, a joey's head and back feet stick out of the pouch opening, and when its mother grazes, the joey is able to nibble at the grass also, learning to eat. At nine months of age the joey will start to leave the pouch for increasing periods of time, returning always to the same teat for a feed until it no longer drinks milk and switches entirely to plants. 

A joey returning for a feed although now too big to go into the pouch.

A joey returning for a feed although now too big to go into the pouch.

A female kangaroo generally has another baby in her womb 'in suspense', which means it has developed just a little bit and then has stopped and waited. When a joey leaves the pouch, the mother starts the development of the one in her womb again, and it is born a few weeks later. Then she will have one tiny helpless joey in her pouch, drinking the kind of milk it needs to develop, and she will have another joey that is out of the pouch but which returns to feed on milk from its own teat in her pouch. That milk will be different from what the tiny joey is drinking,  because the older joey needs milk that will help it get strong as it hops around.  If conditions are bad, such as times of drought when there is not much food around, the female kangaroo may wait until things improve before letting the second baby develop. This means that there are fewer kangaroos born during a drought, which ensures that there is food for the existing kangaroos. The babies are born when the mothers are feeding well and producing good milk, and so that when the young start to feed on solid food, there is plenty for them too. 

Conservation and Threats

©Getty Images

©Getty Images

In a drought, large mobs move into farmlands and parks, even golf courses to find food. This often puts them into conflict with humans, who decide they are pests and sometimes results in them being 'culled', which means many are killed to reduce the numbers.

Kangaroos were for centuries an important animal hunted by Aboriginal peoples of the continent, not only for food but for skin, intestines, and other parts of the body. Traditionally, Aboriginal people hunted only what they needed, so they were not a threat to kangaroos' survival. When European settlers came, they replaced the native grasslands with European grasses for their imported cattle. While this had a bad impact on many Australian animals, such as the bilby, kangaroo numbers increased because they adapted easily to the new grasses and crops, and fences presented no barrier. Today there are four species of kangaroo that are very abundant, and not threatened. Careful harvesting from these four species is permitted, and there is heavy regulation regarding numbers, so that the populations do not become so big that they become a problem, nor are they in danger of getting too small. Harvesting is by licensed, trained kangaroo hunters.


Goodfellow's tree kangaroo with young. ©Getty Images

Goodfellow's tree kangaroo with young. ©Getty Images

Tree kangaroos

In tropical areas of Australia and Papua New Guinea there are kangaroos that live in trees. They are clumsy on the ground and easy prey, so they stay in trees most of the time. There are about ten different kinds of tree kangaroo.

©Getty Images

©Getty Images

Their tails help them balance as they move about from branch to branch by hopping or walking, and can jump from one tree to another. The tails are floppy rather than stiff, and hang down. Their back legs have short, broad feet for better grip. They have strong claws on all four legs. They are the only kangaroos that have front paws that can be raised above their heads, which helps them move about in trees. Their front paws are more flexible than those of ground-living kangaroos, and they can hold food to their mouths with them.

Being tree dwellers, leaves, fruits, flowers and bark form the major part of their diet. Unlike their kangaroo relatives, they are solitary animals, which means they are alone except for females with young.

Not a lot is known about tree kangaroos because of their life in the treetops in thick tropical forests.

Conservation Status and Threats

Tree kangaroos are generally classified as 'Near Threatened'. Numbers of some species of tree kangaroo are not fully known. Goodfellow's tree kangaroo is classified as Endangered.

Threats include habitat loss due to deforestation, and in Papua New Guinea, through hunting.

Read more about tree kangaroos here:

Watch a video of how a kangaroo moves.

http://thekidshouldseethis.com/post/sciencetake-for-kangaroos-tail-becomes-a-fifth-leg

Read the kidcyber page about wallabies