The red kangaroo ( Osphranter rufus ) stands as the largest of all kangaroos, the biggest terrestrial mammal native to Australia, and the largest extant marsupial. The common name for this animal comes from the word "gangurru," which was used by the Guuga Yimithirr people of Far North Queensland. Red kangaroos are so-named due to the color of their fur. This iconic species plays a vital role in the Australian ecosystem, and understanding its dietary habits is crucial to comprehending its survival and impact on its environment.
Physical Characteristics and Adaptations
Red kangaroos are easily identifiable by their distinct features. Males have short, red-brown fur, fading to pale buff below and on the limbs. Females are smaller than males and are blue-grey with a brown tinge, and pale grey below, although arid zone females are colored more like males. Red kangaroos have long, pointed ears and a square-shaped muzzle. Males grow up to a head-and-body length of 1.3-1.6 m (4 ft 3 in - 5 ft 3 in) with a tail that adds a further 1.2 m (3 ft 11 in) to the total length.
Kangaroos are the only big animals to hop as their main method of locomotion. They have two forelimbs with small claws, two muscular hind limbs, which are used for jumping, and a strong tail which is often used to create a tripod when standing upright. On land kangaroos always move their back legs together, but in water, they will kick each leg independently when swimming. Their large tails are used for balance when moving and their Z-shaped hind legs are used for their powerful hops. Red kangaroos have powerful hind legs and large hind feet that enable them to move quickly and use less energy, reaching speeds of up to 39 miles per hour. They can leap over 20 feet and as high as eight feet! They hop over long distances in search of food and water and are also excellent swimmers. The back feet have four toes, but the inner two are fused up to the claws. The double claw at the end is used for grooming and defense. While their front legs are much smaller than their back legs, they still help with movement and grasping food. Their long, muscular tails help them balance when hopping and act like a "kickstand" when standing still or moving slowly.
Red kangaroos maintain their internal temperature at a point of homeostasis of about 36 °C (97 °F) using a variety of physical, physiological, and behavioral adaptations. These include having an insulating layer of fur, being less active and staying in the shade when temperatures are high, panting, sweating, and licking its forelimbs. They have an exceptional ability to survive in extreme temperatures using a cooling mechanism where they can increase their panting and sweating rates in high temperatures to cool their bodies. To survive in harsh conditions and conserve energy, red kangaroos can enter a state of torpor. Red kangaroos also have a high tolerance for consuming plants high in salt content and can survive for long periods without water by reabsorbing water from their urine in the kidneys, minimizing water loss.
Habitat and Distribution
The red kangaroo ranges throughout western and central Australia. Its range encompasses scrubland, grassland, and desert habitats. Red kangaroos inhabit the arid regions of Australia's mainland, except the extreme north and extreme southwest of the country, and the east coast. They can be found in scrubland, grassland, and desert habitats. It typically inhabits open habitats with some trees for shade. Red kangaroos are capable of conserving enough water and selecting enough fresh vegetation to survive in an arid environment.
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Dietary Preferences: What Red Kangaroos Eat
Red kangaroos mostly eat plants and are known as browsers. Red kangaroos are herbivores (folivores) and eat only plants, preferring green herbage, such as flowering plants, forbs, and grasses. They have a varied diet, but they primarily feed on different types of grasses. As grazers, these kangaroos eat a variety of green herbage, grasses and shrubs. One study of kangaroos in Central Australia found that green grass makes up 75-95% of the diet, with Eragrostis setifolia dominating at 54%.
Kangaroos get most of the water they need from the food they eat but will travel great distances in search of water. Red kangaroos are capable of conserving enough water and selecting enough fresh vegetation to survive in an arid environment.
Feeding Behavior and Social Dynamics
Red kangaroos are sociable animals and are often found in small groups of 2-10 individuals, called “mobs.” Red kangaroos occur in small groups, averaging 10, called "mobs." A typical mob has one dominant male, several females with their offspring, and a few young males. Groups are typically made of up a dominant male, several females and their offspring. Males in the group engage in boxing matches to establish dominance. The dominant male leads the mob and gets to mate with the females.
They are mostly active at twilight and during the night, resting during the day in the shade - but they sometimes move around during the day. To keep out of the heat, they are mostly nocturnal and spend most of their day resting in the shade. Kangaroos are most active in the early morning or evening when it is cooler outside. Grazing takes up most of their daily activities. When grazing in a group they are always looking out for danger and they warn others by stamping their feet. When in danger, kangaroos will beat on the ground with their hind feet. This alarm signal is loud and carries over a long distance.
At times, red kangaroos congregate in large numbers; in areas with much forage, these groups can number as much as 1,500 individuals. Occasionally, large numbers of kangaroos come together at dusk to eat when there is plenty of food available.
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Reproduction and Development
Red kangaroos can breed year-round when the habitat offers enough food and water. The breeding season is year-round if conditions are favorable. Females give birth usually to a single young, following a gestation period of about 32 to 34 days. Like all marsupials, kangaroos give birth after a short gestation of about 30 days. Like other newborn marsupials, when a red kangaroo is born, it is incredibly tiny - about the size and weight of a nickel. The baby kangaroo, called a joey, is small and hairless-about the size of a peanut.
Blind and only partially formed, the baby must crawl into the mother’s pouch with no assistance at all. After it is born, the joey climbs into the pouch on its mother’s belly all by itself, using its tiny arms. There is spends another six or seven months drinking milk, and growing larger and stronger until it is ready to come out into the world. Inside the pouch, it attaches to one of the four nipples and stays there to nurse and grow for more than four months.
Around six months old, the joey’s eyes start to open. In the next month, it grows quickly, and its limbs begin to stick out of the pouch. The joey will start to peek out, smelling and exploring its surroundings. When the mother kangaroo bends down to eat, the joey can lean out to nibble on grass and other plants. By about nine months, the joey will start to spend time outside the pouch but can climb back in. The joey will slowly venture further away from its mother but return to be groomed or to nurse. It will not permanently leave the pouch until around 12 months old, and it will continue to nurse for another nine months or so by sticking its head back into the pouch.
One interesting fact about kangaroo milk is that its nutrition changes based on what the joey needs. This means that the milk produced when the joey is inside the pouch is different from the milk made when it spends time outside.
Conservation Status and Threats
The Red kangaroo is faced with no major threats, and it continues to be an abundant and widely distributed species. Red kangaroos are listed as least concern by the IUCN. Currently, there are no significant threats to this species. Intensive agriculture would affect this species, but, as yet, not much of its habitat has been affected. Some argue, however, that competition with introduced rabbits and livestock, particularly during periods of drought, could be a threat.
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According to the Australian Government Department of the Environment, the total number of Red kangaroos is 11,514,298 individuals.
Interactions with Humans
In Australia, kangaroos are actually considered nuisances because of their competition with livestock for resources, fence damage and being a hazard to drivers. Kangaroos dazzled by headlights or startled by engine noise often leap in front of vehicles, severely damaging or destroying smaller or unprotected vehicles. The risk of harm to vehicle occupants is greatly increased if the windscreen is the point of impact.
Like all Australian wildlife, the red kangaroo is protected by legislation, but it is so numerous that there is regulated harvest of its hide and meat. Hunting permits and commercial harvesting are controlled under nationally approved management plans, which aim to maintain red kangaroo populations and manage them as a renewable resource. The kangaroos provide meat for both humans and pet food. Kangaroo meat is very lean with only about 2% fat.