Video: Why did this leopard kill one of its own?

Spotting a leopard in the wild tops the bucket list of many a tourist heading out on safari. So when Ryan Jenkins and his family came across two of the elusive cats brawling in the road on a recent trip to South Africa's Kruger National Park, they thought they had hit the mother lode. Things took a dark turn, however, when they realised that the leopards were locked in a battle to the death.

The footage, captured earlier this year in the southern area of the reserve, shows a juvenile leopard repeatedly being attacked by a much larger rival. When Jenkins and his family first happened upon the cats, the leopards were already entangled in a writhing, dusty ball of claws and spots. "We actually thought for a moment that they could just be playing," Ryan Jenkins explained to Latest Sightings. But the family quickly realised that this was no game.

After 25 minutes of repeated attacks, the smaller leopard eventually succumbed to its larger kin. "The older leopard grabbed the small leopard by the neck and held him down forcefully until you could see the little one suffocate," Jenkins explains. The victor did not stick around to feed on the carcass, although it did sniff and lick it for 10 minutes before wandering off.

So why would a leopard attack and kill one of its own? "It’s very unlikely that this is a territorial dispute, given the size difference between the two cats," explains Dr. Guy Balme, Senior Leopard Program Director for Panthera, the global wild cat conservation organisation. The larger leopard looks like a subadult male of about three or four years old, while the victim is a one- or two-year-old juvenile, Dr Balme told us via email. It's likely that this cat-on-cat violence was a deliberate act by the adult leopard to boost his chances of siring his own cubs.

In zoological circles, it's called "infanticide" and it involves the killing of offspring by an adult animal of the same species. It is common in leopards, and accounts for almost half of all leopard cub mortality. "Infanticide is a natural 'sexually-selected' behaviour in leopards, whereby incoming males kill the cubs of resident males to increase their own chances of siring offspring," says Dr Balme. "Though most victims of infanticide are young cubs, generally less than four months old, our long-term research in the Sabi Sand Game Reserve in South Africa shows that youngsters as old as 18 months can be killed by immigrant males."

The killing of cubs and juveniles helps to bring the mothers of those youngsters back into oestrus allowing the perpetrator of the infanticide to sir the next litter. It's rarely witnessed and, while it may seem cruel, infanticide helps maintain healthy leopard populations. In areas where leopards are at risk from non-natural threats (trophy hunting, for example), infanticide can reach unsustainable levels as the rate of turnover among males is artificially increased.

Panthera, along with SANParks and Singita, is currently conducting a study to assess the population of leopards in the Kruger Park (an area that stretches almost 20,000 square kilometres). "We do know that densities in the neighbouring (and contiguous) Sabi Sand Game Reserve are high – approximately 12 leopards/100 km2 – which is likely close to the upper density limit for the species," Dr Balme points out. "This is one of very few leopard populations that are at capacity, free from anthropogenic mortality."

A leopard population free from unnatural threats provides an opportunity to learn more about how factors like infanticide have a role to play in regulating numbers. While this kind of behaviour may seem brutal, Jenkins and his family were quick to accept that nature should be left to take its course: "we just wished that the little one had been given a chance to live another day, but as we know, that's life in the bush."