Macropus giganteus  (Eastern Grey Kangaroo)

Classification

Phylum:	Chordata
Class:	Mammalia
Order:	Marsupialia
Family:	Macropodidae

Geographic Range

The Eastern Grey Kangaroo, Macropus giganteus, is found in Eastern Australia, especially Queensland, New South Wales, and Victoria, and Tasmania.

Physical Characteristics

Length:	average: 1 meter tall with a 90cm tail
Mass:	average: 50kg

The Macropus giganteus looks similar to the red kangaroo, but is slightly smaller and heavier. It has a small head with large ears. Its fur is steel grey on top and the underside of its belly and tail is lighter. Their nostrils are separated by a strip of light colored fur down its muzzle. The Eastern Grey Kangaroo's tail can reach up to 4 feet long and is used for balance and a prop while standing. Their front forelimbs are smaller than their hind legs with 5 digits for grasping objects. There is not much difference between the physical appearance of a male and a female only that the male usually weighs more than the female. The Eastern Grey Kangaroo has coarser and curlier fur than the Western Grey. The Eastern Grey kangaroos found in Tasmania have fur that is longer, shaggier and browner. The inland kangaroos have darker fur than the coastal kangaroos.

Natural History

Food Habits

Eastern Grey Kangaroos are herbivores. They usually eat shrubs, leaves, grass and herbs. They eat at night, cool mornings and evenings, and sleep during the daytime in shade or in self-dug holes.

Reproduction

The normal sexual mating between the male and female kangaroo takes place during a breeding season of spring to early summer when they reach sexual maturity at the age of 1.5 to 2 years. Then, the females give birth after a gestation period of about 35 days. The young kangaroo is less than an inch long, about the size of a lima bean. The first act of the young kangaroo is to crawl up its mother's belly into the pouch. It then latches onto a teat and nurses. Newborns do not have the ability to suck, so the muscular action from the teat squirts milk into the babies mouth. The newborn remains inside the pouch for about 300days (7-8 months). After that time the baby kangaroo, or Joey, leaves the pouch, but nurses for about 18 months after. The mother kangaroo can produce two types of milk, one for an active joey and one for a developing joey in her pouch. The females have delayed implantation, which is a reproductive adaptation that allows the fertilized egg to cease development and wait depending on the growth of the joey in pouch and on the weather that season. When the mother is ready, the fertilized egg begins to develop. Twins have occurred before, but they are not common.

Behavior

Eastern Grey Kangaroos have an excellent sense of smell, sight, and hearing. They can swivel their ears around to focus on a specific direction. They live in small social groups called "mobs," which are led by a mature male and consists of younger males and females with their young. The oldest male uses force to maintain control. When they sense danger they thump the ground with their hind leg to warn the rest of the mob. Eastern Grey Kangaroos are known for being aggressive and attacking. The females and joeys communicate with a series of clucks and squeaks. The males communicate with coughs and grunts emitted while fighting.

Habitat

Eastern Grey Kangaroos are found usually on grasslands or open woodlands.

Conservation/Biodiversity

They have a population of about 2 million and are closely related to the Western Grey Kangaroo. Since they are herbivores they have many carnivorous predators. Their predators are mainly the dingo, the python, the goanna, and some larger carnivorous birds. Also, farmers shoot them since they jump fences and eat on sheep land and grazing land.

Economic Benefits for Humans

Positive

Kangaroos are primarily endemic to Australia. There was no information regarding the positive consequences for humans, except for their use as a possible food source.

Negative

They can cause some problems for the farmers productivity due to their ability to invade grazing lands.

Comments

The Eastern Grey Kangaroo is a very powerful jumper. They can reach heights of over 9m in one bound. They have a lifespan of about 18 years and can reach a top speed of around 60KPH. The word "macropod" literally translates into "big-footed," which is where the kangaroo got its name. The Eastern Grey Kangaroo is known for "walking on all fives." This means that the front legs and the tail support the body, while the hind feet move forward. Females are usually called "Flyers," Males, "Boomers," and young are called "Joeys."

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Entry Author:

Kalyn Quintin

Union College

2003