Banded mongooses live in extended-family groups, with as many as ten females breeding at the same time. When they're about a month old, pups leave the communal den to forage with the adults. That's when a pup usually begins to associate exclusively with one particular adult — not necessarily a parent — that provides nourishment and protection. One might assume that the adult chooses the pup it wishes to assist.

Not so, says Jason S. Gilchrist of Napier University in Edinburgh, Scotland, who has long studied banded mongooses in Uganda.

His latest research demonstrates that the pups do the picking, then establish and jealously defend a territorial zone of about a yard radius around their adult "escort." Other pups that venture too close are chased away.

In field experiments, Gilchrist separated pups from their escorts and held them captive for two days. During that time, the adults interacted freely with other pups. When Gilchrist returned the detained pups to the group, however, they quickly reasserted exclusive rights to their escorts. The adults, it seems, are the passive partners in the relationship.

Generally, when pups reach three months of age, they no longer require their escorts' services and begin to fend for themselves. Gilchrist concludes that even in cooperatively breeding societies, "conflict can be as rife as cooperation."

The findings were detailed in the Proceedings of the Royal Society B.