Friday 20 October 2017

Banded mongooses pick on close female relatives when it comes to kicking members out of the group

By Jessica Pitocchi

The savage and sexist behaviour is surprising coming from such social animals.

Banded mongooses pick on close female relatives when it comes to ejecting members from their social group, a new study has shown.

Dominant members of banded mongoose groups select females as the prime target because the dominant one’s pups are less likely to survive if there’s too many females breeding in the group.

These mass evictions are highly violent and often lead to injuries or even death.

Most animals are less aggressive towards family members – which makes this behaviour from the social animals all the more surprising – but the reason is that unrelated mongooses are more likely to fight back which makes it more difficult to evict them.

Lead author Dr Faye Thompson, from the University of Exeter, said: “Targeting close relatives for eviction like this is the opposite of what we would expect social animals to do.

“Our research shows that related females submit more easily because they are more sensitive to the costs they inflict on their relatives by fighting to stay in the group.

“As dominant banded mongooses need to evict rival females to reduce competition for their own offspring, their best strategy is to target close relatives.”

The trend for targeting related females was only seen in evictions of mongooses that were old enough to defend themselves – supporting the conclusion that relatives are preferentially targeted only when they are capable of resisting eviction.

Professor Michael Cant, who leads the long-term study, added: “We’ve long wondered why some individuals are marked out for violent attack and eviction, whereas others are permitted to stay.

“Our new study shows that a crucial determinant is whether victims can put up a fight, and predicts that closer kinship sometimes goes hand in hand with more intense aggression.”

The paper, Explaining negative kin discrimination in a cooperative mammal society, is published in the journal Proceedings of the National Academy of Sciences.

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