Thursday, December 22, 2016

Promiscuity of mother lioness saves cubs in Gir: Study

Promiscuity of mother lioness saves cubs in Gir: Study

Promiscuity helps Indian lionesses protect their cubs from adult males that instinctively kill the offspring of rivals, a three-year study in Gujarat's Gir national park revealed this exceptional Asiatic lion trait.

The behaviour, common among tigresses and many top predators in the wild, is not seen among African lions that live within a tight-knit pride comprising one, or sometimes two, alpha males and about half-a-dozen females who are mothers, daughters and granddaughters.

Infanticide is widespread when a challenger takes over the dominant position in the pride from an alpha male who monopolises reproduction until he is ousted, normally because of old age or injury.

But wild Asiatic lions, found only in Gir now, have adopted a different pride structure and strategy to protect their young, scientists at the Wildlife Institute of India (WWI) found.

"Promiscuity in lions was never known," said Satotra Chakrabarti, a scientist at the Dehradun-based WWI. "African female lions do not show this tendency. Our study brought up this interesting fact that Asiatic lions are promiscuous. They do so to confuse paternity and protect their cubs from infanticide."

Difference between social behaviour of African and Asiatic Lions

African Lions

Asian Lions

Male own prides

Female own prides

1-7 males lives in single coalition

Male owns territories because of which they overlap many prides

Cubs are protected by the males of coalition

Cubs are protected through confused paternity as lionesses are promiscuous

Female lionesses are mothers, daughters and granddaughters that stick to a coalition

Female lionesses bear off springs move out to form separate prides

Single lion entry is difficult as it has to oust the existing lions. It eventually becomes a threat to cubs

Single lions easily enter prides and protect cubs (confused paternity)

This is possible because Asiatic lionesses are in charge of prides, unlike in Africa. Males own territories, which overlap several prides.

The first-ever research on social and behavioural patterns of Gir's lions showed females often mated with as many males crossing their prides as possible, thereby making it hard to discern infant paternity.

Such strategic promiscuity ensures males stop killing cubs if there is a risk that the offspring might be their own.

This is necessary because Asiatic males exhibit intense hierarchies, with an alpha being the boss in mating and feeding, Chakrabarti said.

Scientists, who conducted the study at Gir for three years since 2013, concluded that promiscuity is an adaptation these descendents of African lions, who migrated to Asia thousands of years ago, have deployed to good effect.

The study report — titled Dominance and Promiscuity: Social Organisation of Gir Lions — says the mother's strategy has altered cub mortality to some extent.

Kaushik Banerjee, another expert at WII, said 30% lion cub deaths in the world are the result of infanticide. But the toll is slightly lower in India.

YV Jhala, a senior expert with WII, agreed and gave credit to female promiscuity for the lower number of cub deaths.

The 2015 census shows Gir has 523 lions, an increase of 27% in five years, with a healthy litter of cubs.

Read | Three lions at Gujarat's Gir condemned to life in captivity for killing humans

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