The largest marsupials are the kangaroos, which belong to the family Macropodidae. These iconic Australian animals display a remarkable range of sizes, from small wallabies to the massive creatures that dominate the grasslands. The question of which species holds the title for the biggest often comes down to a comparison of height versus overall body mass. The answer lies in the specific metrics of weight and standing height among the largest species.
The Reigning Champion: Size and Statistics
The largest living species of kangaroo, and the largest extant marsupial, is the Red Kangaroo (Osphranter rufus). This creature holds the size record due to the sheer body mass achieved by the adult males, often referred to as “boomers” or “big reds.”
The size difference between the sexes, known as sexual dimorphism, is highly pronounced in this species. While females typically weigh between 18 and 40 kilograms (40 to 88 pounds), males can weigh approximately twice as much, ranging from 55 to 90 kilograms (121 to 198 pounds). The most massive recorded males can exceed 90 kilograms (200 pounds), solidifying their status as the heaviest of the macropods.
When standing upright, a large mature male Red Kangaroo can reach a height of over 1.8 meters (5 feet 11 inches). Exceptional individuals have been reliably measured at up to 2.1 meters (6 feet 11 inches) tall. This combination of towering height and immense muscle mass, particularly in the hindquarters and tail, makes the Red Kangaroo the heavyweight champion of the family.
Ecology and Range of the Largest Kangaroo
The Red Kangaroo’s immense size is an adaptation to the vast, often harsh, interior of the Australian continent. This species is predominantly found across the central and western arid and semi-arid regions of mainland Australia. Its distribution covers a huge expanse, avoiding only the more fertile eastern and southern coastal areas and the northern rainforests.
The preferred habitat of the Red Kangaroo includes open plains, grasslands, and shrublands, where it grazes primarily on grasses and forbs. Their nomadic behavior is driven by the erratic availability of food and water sources in this dry environment. This necessitates efficient movement, and the Red Kangaroo’s powerful legs allow it to travel huge distances, reaching speeds up to about 60 kilometers per hour (37 mph) in short bursts.
The Red Kangaroo is also known for its behavioral adaptations to the heat. They maintain a stable internal temperature by seeking shade, panting, and licking their forelimbs to promote evaporative cooling. While they live in flexible social groups called “mobs,” males often engage in ritualized fighting, or “boxing,” to establish dominance and gain access to females, a behavior that is facilitated by their massive size and robust upper body strength.
Comparing Size: The Next Largest Species
The Red Kangaroo’s title is often challenged by the second largest species, the Eastern Grey Kangaroo (Macropus giganteus). The Eastern Grey is a very large animal, frequently encountered in the fertile, eastern part of the country.
The Eastern Grey Kangaroo exhibits a different body composition when compared to its red counterpart. While a large male Eastern Grey can stand taller than a grown man, reaching heights up to 1.8 meters (5 feet 11 inches), it is lighter in body mass than the Red Kangaroo. Adult male Eastern Greys typically weigh up to 66 kilograms (145 pounds), though some can reach around 78 kilograms, placing their maximum weight below that of the heaviest Red Kangaroos.
Following closely in size is the Western Grey Kangaroo (Macropus fuliginosus), found across southern Australia. A large male Western Grey typically weighs up to about 54 kilograms (119 pounds). While the Eastern Grey is often the tallest of the three major species, the Red Kangaroo retains the title of the biggest due to its superior weight and overall bulk.