Why Are Kangaroos So Buff? A Zoologist’s Explanation.

The kangaroo is a large marsupial that is endemic to Australia. They are known for their iconic jumping mode of locomotion and possession of a pouch in which their offspring develop and live. 

There are 4 species of kangaroo; the Red Kangaroo, Eastern Gray Kangaroo, Western Gray Kangaroo, and Antilopine Kangaroo. The height, weight, and average strength vary between the species and sexes, with the male red kangaroos coming out on top for all categories. 

Kangaroos are labelled as one of the buffest animals in the world. The internet is filled with images of kangaroos showing off their buff chests and muscular frame. But why are these marsupials so physically powerful?

Kangaroo standing on the ground
Kangaroo standing on the ground 
Credit: Mark Wagner by CC: 3.0

Scientific Name: Macropodidae spp.

Male Vs Female Kangaroos Muscle Mass

Male and female kangaroos show a significant difference in terms of muscle mass, with males showing a much higher percentage. It is thought the ‘bulging biceps’ of male kangaroos is a sexually selected trait that helps them attract a mate. 

One study found that forelimb muscle mass in males was much heavier in males than it was in females. This suggests a different use for the same limb between sexes, with the main usage for males being mate attraction. Additionally, male kangaroos use their strong muscles to wrestle male love rivals. 

Pure muscle mass can make up around 50% of a kangaroo’s total body weight. On average, kangaroo species weigh between 35 and 90kg. However, males are significantly heavier than females, often up to twice as heavy. 

Although kangaroos are morphologically predisposed to be muscular and strong, it is a sexually selected trait that influences the difference in muscle mass. Specifically, the forelimb muscle mass in males is heavier to aid male-male combat and attract females. 

Why Some Kangaroos Get So Buff

There are a number of reasons why kangaroos are so naturally buff. They have the strongest and most muscular legs out of all the ‘hopping’ animals. these marsupials have an array of factors that work in their favour to make them incredibly muscular.

Gifted Genetics

The largest species in the Macropodidae family is the red kangaroo. It also boasts the title of the largest marsupial in the world. Due to their strong and muscular forelimbs, hindlimbs, and tail, kangaroos are powerful jumpers and are easily able to stand upright.

Their thick tail acts almost as a third leg, helping to keep them stable when they stand upright on their hind limbs. In fact, their tail is so powerful that it equals the strength of both their hind legs combined!

In order to possess and maintain their muscular physiques, kangaroos have large hearts and high levels of muscular mitochondria. As such, they have a high rate of aerobic respiration to generate enough ATP for muscle contractions. Their muscles also have a high rate of oxygen uptake, which is a pattern among all athletic animals. 

The red kangaroo has a muscle mass that accounts for half its total body weight. The majority of the muscle mass is concentrated around the hind legs and pelvis highlighting the powerful jumping ability kangaroos possess.  

Fighting for Dominance

Over time, kangaroos have evolved incredibly muscular bodies to aid their fighting ability. Males often engage in physical combat, and having big, strong, and powerful muscles is advantageous. Males mainly fight for supremacy and for access to females, in the same way, big cats and primates do. 

Kangaroos are very social animals, and they live in groups called “mobs”. In these mobs, there is one dominant male. The alpha will get to choose which females in the mob he wants to mate with. Young, subordinate males in the mob may try and fight the alpha for dominance or leave the mob to take over another one. 

Dominant males in a mob usually only maintain the alpha role for around a year. This is because they struggle to maintain the physical strength and endurance required to continuously fight off rival males. 

Posturing and Mating Rights

Different animal species implement different mating strategies. In order to attract females, male kangaroos box with other males. During the fight, each party will flex and show off their muscles, in a way that entices females. 

When females are ovulating is when males become most aggressive and intent on pursuing a mate. Fights over males may be short or long and are usually intense. The larger and more muscular males predominately win fights.

Male kangaroos never stop growing. This allows them to maintain their physique and so mating supremacy, even as they grow older. This trait is driven by females’ preference for the most muscly males. 

Pair of Red Kangaroos
Pair of Red Kangaroos standing on their large, hind feet using their tails for balance 
Credit: Donald Hobern by CC: 2.0

Scientific Name: Macropus rufus 

Speed of Movement – Hopping

Kangaroos are most well-known for their unique bipedal hopping locomotion. This varies for the majority of other mammals, that use a quadrupedal form of locomotion. Kangaroos are also the largest, hopping mammal in the world. 

The legs of a kangaroo have very flexible tendons, that are adapted for storing energy for jumping. As a kangaroo descends from the air and its feet hit the ground, the tendons in the legs squeeze together and accumulate the energy required to jump back into the air. Virtually no energy is spent on breathing. Instead, it is mainly focused on jumping locomotion. 

The tail of a kangaroo acts as a fundamental balancing tool during jumping. Combined with their large feet and plenitude of muscles, kangaroos are capable of jumping 25 feet in distance, 6 feet in height, and can travel around 43mph. 


Red kangaroos are the most buff of all the species. They have incredibly prominent chest, abdomen, leg, and arm muscles. Kangaroos are known for their aggressive temperament and fighting behaviour.

Fights between males are called “boxing matches”, due to their resemblance to human boxing matches. Both parties use their strong arms to throw punches and also use their sharp claws, often drawing blood on the opponent. 

The “kickbox” is another iconic kangaroo movement, in which they kick their opponent with their hind legs while maintaining balance on their tail. The strongest and most muscular males tend to win fights.  

Kangaroo Strength and Power

“Strength” and “power” are certainly two words people associate with kangaroos. These boxing beasts are certainly one animal you don’t want to mess with! They are known to show aggression toward people and other animals, and there have even been reports of kangaroos killing dogs. Although they may seem cute and cuddly, they can be dangerous. 

Kangaroos are herbivores, meaning they do not need to be buff to hunt and kill their prey. These marsupials also have very few natural predators, meaning they seldom need to fight off animals trying to eat them. 

Instead, the strength of kangaroos is thought to be the result of their anatomy, morphology, and adaptation to their environment and behaviour. 

Kangaroos inhabit the harsh and arid regions of Australia. Their thick, muscular limbs allow them to quickly and easily cover great distances. This is imperative in such an environment because essential resources such as food and water are scares and spread out. 

The strength of a male kangaroo also plays a key role in its reproductive success. The buffest kangaroo is likely to establish dominance within a mob, and therefore have the best chances of mating with the females within the mob. 

Are Kangaroos Stronger Than Humans?

On average, kangaroos are between 6 and 8 times stronger than a human. They have a bite that exceeds 900 pounds per square inch. This equals the bite power of many apex predators. In comparison, humans have a bite force of only 162 psi. 

Additionally, a male kangaroo is capable of throwing punches with a force of roughly 275 pounds. Some of the strongest male humans can rarely punch with a force of more than 45 pounds, which is around 6 times less than a kangaroo. 

Regarding their body weight, kangaroos certainly pack a punch, although their kick is much more powerful. The actual strength of an individual is determined by the species, sex, and size. 

If you are a highly trained martial artist or bodybuilder, you will likely have greater accuracy and force than a kangaroo. Generally, kangaroos are stronger than people in every aspect, apart from their punches. 

How Powerful is A Kangaroo Kick?

The kick of a kangaroo is its most dangerous weapon. These marsupials have very strong and muscular hind legs. Usually, they are used for their jumping locomotion, but they become deadly assets when used in a fight. 

The red kangaroo can deliver a kick with a speed of more than 40 miles per hour. They also kick with a force of around 759 pounds of force. One kick from a kangaroo could easily shatter your bones or even kill you. 

Two male Red Kangaroos
Two male Red Kangaroos fighting and exhibiting kickboxing
Credit: Dellex by CC: 2.0

Why Kangaroos Have Huge Biceps

You will likely have come across a photograph online of a male kangaroo flexing his huge biceps. Although their legs are much more powerful than their arms, the forelimbs are still important. 

There are two main reasons kangaroos have big biceps: for attracting females and winning fights against other males. 

Females are most attracted to males with big biceps, as they imply he is powerful and will make for an excellent father due to having good genes. During fights, males flex their biceps to try and entice females. 

Male-male kangaroos fights occur most often during the breeding season. Males with larger muscles are most likely to win a fight. Males throw punches during combat, hence evolution has selected huge biceps, in order to throw powerful punches. 

Verdict: Why Are Kangaroos So Buff?

Kangaroos can certainly claim the title of one of the buffest marsupials, if not animals in the world. Out of all the kangaroo species, the red kangaroo is the largest and most powerful. 

The morphology and muscular bodies of kangaroos are specially adapted to aid their iconic hopping mode of transportation. They have incredibly powerful leg muscles that enable them to jump large distances, which is imperative in the Harsh Australian environment. 

Additionally, sexual selection plays a huge role in the toughness of kangaroos. Female kangaroos are most attracted to males that have large and prominent muscles. This is because it indicated they have good genes that will be passed on to their offspring. 

Male kangaroos are known for engaging in dangerous fights. Usually, these fights are over females, during which they will show off their big muscles. If a male looks buff, it is because he has a lot of muscle, which exercises his strength. 

If a male kangaroo is stronger than his opponent, he has a very good chance of winning the fight. Winning males are likely to become the alpha of a mob, which means they have the pick of all the females. 

As such, a number of interlinking factors contribute to the buff physique of kangaroos. 

A male kangaroo
A male kangaroo flexing his muscles to attract a female
Credit: Tracey & Doug by CC: 2.0

FAQ: Jacked Kangaroos