Banded mongooses in Queen Elizabeth National Park, Uganda
Alamy Stock Photo
Female banded mongooses lead their groups into conflicts with rivals so that they can mate with males from neighbouring territories during battle, while males in their own groups are distracted.
Michael Cant at the University of Exeter in the UK, and his colleagues have been studying groups of wild mongooses in Queen Elizabeth National Park in Uganda for the last 25 years.
Banded mongooses are highly territorial and live in groups of about 20 adults, clashing violently with rival groups up to three times a month. The researchers suspected that females were leading their groups into these fights with rival groups in order to search for new mates.
“Banded mongoose groups are so closed,” says Cant. “Hardly anyone ever leaves, so levels of relatedness within the group build up over time.”
Female mongooses in the same group enter into heat synchronously and deliver pups on the same day. While the females are in heat, the males shadow the female group members and guard them from rival mates in the same group.
The team captured video footage of females mating with males in rival groups during conflicts, in moments when they were not guarded by their own males. They found that the likelihood of a fight occurring increased when the females were in heat. They say this suggests that the females initiate and lead their groups into fights rather than the males.
“The probability of getting involved in these fights goes up as the age of the group goes up, and as the level of inbreeding in the group goes up,” says Cant.
The researchers compared the offspring produced by pairings between 499 males and 377 females, finding that engaging in more intergroup conflicts increased the number of pups produced and their rate of survival more steeply for females than it did for males.
The behaviour is an example of exploitative leadership, says Cant, in that the adult females gain a reproductive benefit, while the rest of the group suffers: pups and male adults are killed more than females during battles.
“Organised collective violence extends well beyond humans and beyond the species people typically think about, [such as] chimps,” says Cant.
Journal reference: PNAS, DOI: 10.1073/pnas.2003745117
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