The term “mob” is a collective noun used to describe a group of animals, much like a “pride” of lions or a “flock” of birds. This term is most prominently associated with a large, iconic marsupial of Australia. This article explores the nature of this animal group, detailing its composition, the reasons for its formation, and the specific actions members take for survival.
Which Animal Forms Mobs and Why
The animal whose group is called a mob is the kangaroo, a marsupial indigenous to Australia. These groupings are fluid, exhibiting a fission-fusion social structure where they split into smaller foraging units and then re-form into larger aggregations. Although some mobs can swell to over 50 individuals in favorable conditions, they are frequently encountered as smaller units, often ranging between five and ten members.
A typical mob is composed of several adult females (does or jills), their young (joeys), and a few males (bucks or boomers). The social environment is complex, featuring a dominance hierarchy among males that determines breeding rights. The largest male will assert his authority and tend to the females who are near estrus.
The primary reason for forming a mob is safety, acting as a defense mechanism against predators like dingoes. Shared vigilance significantly increases the likelihood of detecting danger before it poses a threat. Furthermore, the mob provides a setting for social learning, where younger kangaroos acquire survival skills by observing older members. Social cohesion is reinforced through behaviors such as nose-touching and sniffing, which serve as a non-aggressive form of greeting and recognition.
Collective Actions and Group Defense
The mob’s collective actions are centered on shared activities such as feeding and coordinated defense. While grazing on grasses, multiple individuals maintain a watch, allowing others to forage with their heads down, effectively sharing the burden of remaining alert. This collective awareness is an advantage of the group structure, optimizing both feeding time and safety.
When a threat is perceived, the mob utilizes distinct alarm signals to alert all members. The primary warning is a loud, percussive foot thumping, where one kangaroo forcefully strikes the ground with its hind foot. This vibration travels through the earth, instantly communicating danger to the rest of the group.
Upon receiving the alarm, the mob often scatters into a high-speed, bounding retreat, a coordinated confusion that makes it difficult for a predator to focus on a single target. During this retreat, the group structure protects the most vulnerable members, particularly the joeys and juveniles. Adult kangaroos, especially the females, position themselves to shield their young.