Researchers have discovered that dwarf mongooses are more willing to help in a mob attack if they’re friendly with the individual who sounded the alarm. Dwarf mongooses form “friendships” and help each other out in a pinch. The details are in a paper that was just published in the journal Biology Letters.
Dwarf mongooses (Helogale parvula) are small carnivores found throughout east and southern central Africa. They live in empty termite mounds and have strict social hierarchies. Normally, only the top female gives birth to offspring and the subordinates help raise the babies. Mongooses are cooperative with each other as well as with their hornbill partners—birds that forage nearby. Mongooses will sound the alarm if they see something dangerous and the hornbills will do the same as part of a mutualistic relationship. If a predator approaches their home, mongooses will often engage in “mobbing” behavior to drive the animal away. The mongoose that spots the predator will sound an alarm to alert others—but not all calls are taken seriously. The research team speculated that factors such as hierarchy and friendship might affect these mobbing calls.
Scientists from the University of Bristol studied a group of dwarf mongooses in South Africa. The animals were already used to the presence of humans, ensuring that the mere presence of researchers wouldn’t be enough to affect the animals’ behavior. They first determined the closeness of different mongoose pairs based on grooming frequency and time spent together when foraging. The team then recorded alert calls and played them back to see how the mongooses responded.
The researchers found that mongooses were much quicker to help when they heard a mob alert from a mongoose they were already friendly with. The closer the bond with the groupmate, the more likely a mongoose was to react to the call. This shows that the “friendships” seemed to encourage action from groupmates, potentially helping these individuals in the future when the roles are reversed.
The findings show the importance of friendships in social animal groups. Mobbing is a risky behavior but not taking action can be even riskier for the mongoose sounding the alarm. Having some good friends ensures that an individual will always have “back-up” and those same friends can later rely on their buddy.
Julie M. Kern & Andrew N. Radford. Social-bond strength influences vocally mediated recruitment to mobbing. Biology Letters (2016).