In doing so, they act much like street gangs, gathering together to protect their turf from interlopers, says a leading lion expert.
The bigger the gang, the more successful the lions are, information that could help conserve wild lions.
The discovery helps explain why lions, uniquely among the cat species, live together in social groups.
Lions stand out amongst all the cat species for their gregarious nature.
Across Africa and Asia, lions form prides of varying sizes comprising one or more males and often numerous females and cubs.
The bigger the gang, the more successful it is at controlling the best areas.
Lion expert Craig Packer
But why they do so has remained a mystery. A long-standing idea is that female lions socialize in order to hunt cooperatively. But despite the common sight of multiple females working together to outflank and bring down large prey, there is no clear link between how many lions hunt together and their hunting success.
Another is that lions gather to protect territory. Indeed, a range of animals from social insects to primates form social groups that defend territories against competitors.
But while there has been anecdotal evidence that bigger groups have a competitive advantage, the idea has never been rigorously tested over long periods of time.
That has now changed with a study analyzing the behavior of 46 lion prides living in the Serengeti National Park, Tanzania.'Street Gangs'
Larger prides with more adult females not only produced more cubs, as might be expected, but the females within these prides were less likely to be wounded or killed by other lions.
Prides with more females were also more likely to gain control of areas disputed with neighboring prides, and those prides that recruited lone females improved the quality of their territory.
"The most important way to think about this is that lion prides are like street gangs," says Packer.
"They compete for turf. The bigger the gang, the more successful it is at controlling the best areas. The main difference from humans is that these are gangs of female lions."
Large coalitions of female lions are so successful at dominating small neighboring prides that male lions step in to try to alter the balance of power. Males will often attack and attempt to kill female lions in neighboring prides to tip the odds in favour of their own pride.