Photograph by Uri Golman, Nature Picture Library
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An Asiatic lioness rests with her two cubs in Gir Forest National Park.

Photograph by Uri Golman, Nature Picture Library

How Asiatic lionesses shield their cubs from killer males

Infanticide is common among India's lions, but females have developed a clever strategy to keep their cubs safe.

The lioness known as FLG10 is a good mother and fierce hunter, providing for her cubs in the last stronghold of Asiatic lions in Gujarat, India.

But until recently, no one knew just how extraordinary of a parent she really is.

Like most young females of this endangered lion subspecies, FLG10 reached sexual maturity and mated with members of her primary coalition, the group of males that most frequently patrolled her pride’s territory in Gir National Park.

Then, around 2015, she did something never before observed in lions: She mated with males from a nearby coalition. And then with males from another. (Read more about Asiatic lions and why they’re thriving.)

To the scientists tracking her, FLG10 appeared to be mating with a strategy in mind. As it turns out, she was.

By mating with males from every coalition that entered her territory, the now 10-year-old lioness was likely protecting her cubs from infanticide by deliberately obscuring the identity of their father.

It worked—none of her cubs were killed, the researchers claim in a new study in Behavioral Ecology.

“If an adult lion comes across a cub that he feels was not sired by him, he’ll kill that cub,” which then leads the female to breed again, says study co-author Stotra Chakrabarti, a biologist at the Wildlife Institute of India. (Read why animals sometimes kill their babies.)

“Females mate with multiple males and confuse paternity among the males so they’ll consider all the cubs their own.”

A successful strategy

In addition to observing radio-collared lions, Chakrabarti and his team pieced together FLG10’s family tree using observational data collected by researchers in the decades since his mentor, Yadvendradev Jhala, began the long-term monitoring project in 1996.

Next, to see if other females were using the same strategy, the team spent four years monitoring nine female prides—including FLG10’s—and 11 male coalitions. The results showed they were, frequently and quite effectively.

Ultimately, every lioness that gave birth at least twice during the course of the study was witnessed mating with multiple males. Amazingly, no lioness lost cubs to a coalition whose members she had mated with. (See a map of the lion's decline worldwide.)

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However, there are some unknowns in the multi-male mating hypothesis, notes Craig Packer, director of the Lion Research Center at the University of Minnesota.

For instance, it’s assumed that males from different coalitions aren’t brothers or cousins. If they are, they have other reasons for not committing infanticide, says Packer, who is also a National Geographic explorer.

From Asia to Africa

Mating with multiple males is not observed in African lions, likely because of the difference in prey availability between the two groups, says Meredith Palmer, a postdoctoral researcher at Princeton.

Abundant deer in and around Gir have led Asiatic lions to develop a social system composed of female prides with two to four lionesses and male coalitions typically with two members. Lions share their kills, so the smaller prey in Gir more easily supports smaller groups. The prides hold small territories, and the coalitions patrol larger tracts that contain multiple prides. The trouble for cubs is coalition territories overlap, meaning the cubs are likely to run across unrelated males.

This isn’t a problem for African lions. Large, migratory prey support large prides that are exclusive (for a few years) to a single coalition. Females are faithful to their breeding partners, and fathers and uncles keep potentially infanticidal males away until they’re displaced by a new coalition.

This study adds to a growing body of research that allows comparisons of the Asiatic and African species and their societies.

“Lions are a lot more behaviorally plastic than we thought,” Palmer says. “Maybe they’re adapting genetically, but they’re definitely adapting behaviorally to these different circumstances.”

Marauding males

The genius of the multi-male mating strategy is that it raises the stakes for males, Chakrabarti says.

“The cost to males for killing their own cubs is so high that they don’t kill cubs at all if they’re familiar to the females,” he says.

But the strategy also has its limitations—it can’t protect against new coalitions of males that the females didn’t have a chance to mate with.

Tragedy struck FLG10’s pride in 2017 when a new coalition of males swept through, killing her female and male cubs along with the rest of the pride’s young. After fighting off the primary mating coalition, the new males established themselves as the leaders. (See National Geographic's most stunning pictures of big cats.)

“They want their own offspring to be born and thrive. So if those females already have babies, these males don’t want to hang around and wait for these babies to grow up,” Palmer says.

Though no mother wants to lose her cubs, the invading males might actually benefit the species in the long run by injecting new genetic diversity into their pride.

And, with only about 600 animals left in the wild, Asia’s last lions need all the help they can get.