Last updated December 7, 2017 at 5:01 pm
Mongooses have a pretty hard life chasing after scarce resources and dodging predators. And if they set out across the desert in search of a better life, they don’t exactly get welcomed with open arms. According to new research, recent immigrants to mongoose colonies are viewed with suspicion and not trusted. It takes up to five months for them to become fully integrated and the rest of their new community to begin to treat them as equals.
Dwarf mongooses within a group are remarkable team players. When members of the group are foraging for food, others will stand guard and keep watch for predators. If one is spotted, they will call to warn the rest of the group. The guards also call to announce to the rest of the group that they’re watching, letting them know someone is keeping an eye out and that they’re free to keep foraging.
The researchers found that initially, recent immigrants will rarely take this lookout role, and when they do try to take part and cooperate with the other members, their new groupmates ignore them. It takes 5 months before things settle down and the new arrivals become fully integrated and valued members within mongoose society.
This initial reluctance to act as lookout doesn’t seem to be due to selfishness or bludging off the other members, according to the research leader Julie Kern from the University of Bristol. “Recent immigrants are typically exhausted and run down, as evidenced by a loss of weight. Even if they tried, they couldn’t contribute fully at first because other members don’t yet know them.”
Dwarf mongoose societies are headed by a dominant male and female, with a hierarchy of smaller mongooses essentially waiting in line for their turn to become head honcho. However, as a mongoose if you were a little lower down the line, you could potentially move to a different colony with predominantly smaller mongooses and jump further up the queue. This queue jumping isn’t without its challenges – moving from one mongoose colony to another is a physically demanding and lonely task, with stress and difficulty of being self-sufficient and having to forage for food while staying vigilant to outside threats without having other’s support often meaning the new mongoose arrives at the new colony undernourished. It is therefore not surprising there might then be a period of them recovering back to full strength once they have joined the new group, and an adjustment period for both immigrant and the community itself.
Using a series of experiments in which they played previously recorded mongoose calls, the researchers showed that foragers responded significantly less to the surveillance calls of recent immigrants compared to those from resident group members. When they heard the call of a new immigrant, they continued to spend more time looking around for predators themselves. But, those differences in response to new members also disappeared after a few months once they had learned they could trust the new member.
This addition to the colony size can be an advantage, providing more support in protection from predators and finding food, while also potentially adding a larger, fitter, breeding partner into the mix.
There is a real temptation to draw parallels between this story and human society. However like most animal research, we need to at least try to avoid anthropomorphising the results and their meaning. These are mongooses, not humans.
“Given a chance, immigrants can become valued members of mongoose society,” said researcher Andrew Radford. “The increased group size that results is beneficial to all.”
The research was published in Current Biology
Videos courtesy of Julie Kern, Unviersity of Bristol
Top image courtesy of Shannon Benson