Before I start this blog, I need to remind myself to avoid the temptation to anthropomorphize. Dwarf mongooses are not people, no matter how interesting, complex and outright cute they are. Now, back to the topic at hand.
Small, tasty mammals like dwarf mongooses have one main goal in mind throughout their entire lives:
Try to not get eaten!
To combat this, they work together as a tightly-knit family group (a band or business of mongooses), trusting each other with their lives. However, due to their complex social and breeding structure, new members are constantly joining the family. This got me thinking – are there any inherent trust issues?
Firstly, and briefly, dwarf mongooses have a typical cooperative breeding society, very similar in fact to that of African Wild Dog. There is a dominant breeding pair, and they’re the only group members guaranteed to have offspring. Every other member of the family has an important part to play and will fulfil various duties such as grooming, cleaning, keeping a lookout, and helping rear the young. Although dwarf mongooses are selfless in their approach to raising young, each member ultimately aims to pass on their own genes.
Following on from the alpha pair, there is a linear dominance hierarchy for each sex, meaning that individuals who rank lower in the hierarchy of the group, have a long ladder to climb to reach that breeding position.
This means that realistically for some members of the group, the best option is to actually leave the group and join a newer band where there are fewer same-sex individuals. Because they are new arrivals and possess new genetic material they effectively join a group higher up the queue.
When a new mongoose joins a group, that means there are now more mongooses to act as a lookout against predators. Right? In reality, it’s more complicated.
Biologists at the University of Bristol in the United Kingdom studied exactly this process, and what they found was rather interesting. They found that new immigrants rarely served as sentinels. It wasn’t until they’d been in their new groups for five months, on average, that they spent as much time working as a lookout as the other mongooses did.
This means that Mongooses essentially go through a transition phase before they’re fully integrated into the new group. In part, that’s because newcomers arrive exhausted and underweight. They need time to recover before becoming fully contributing members of mongoose society. But the existing group also takes a while before they trust newcomers.
Typically a mongoose on sentinel duty will indicate the all clear with a call once they have surveyed the surrounding area that the band is foraging in. The others respond back. By replaying a recording of a subordinate member’s surveillance calls in the study, the researchers found that mongooses responded far less to the sentinel calls of recent immigrants than to those from others they already knew and trusted.
The more they trusted the sentinel, the more they would keep their head down and forage. The less trust they had, the more they would lift their heads to scan for danger themselves. This shows that mongooses don’t just take a sentinel’s call at face value. They know who is making the surveillance signal and they consider the source. A dominant group member on duty makes them more relaxed. A new immigrant on duty is not as reassuring.
Ultimately though, increased group size really is beneficial to all members of a group—new immigrants just need a chance to get settled. Does this settling-in process mean that dwarf mongooses have trust issues? Well, I for one am not convinced, but it certainly does give me a new appreciation for the intricacies and daily struggles they go through. And I definitely will be keeping an eye out to see if I can spot a newcomer to the group next time I stop at dwarf mongoose!