How to Age a Lion

The trick, I’ve found, is to start with the darkness of the nose. Next, check for a Mohawk if it’s a male. Then tally up the scars on the face. If we’re lucky and the lion is yawning, score the staining and wear of the canine teeth. And don’t forget to look for a dangling lower lip. Checklist complete: we’ve just estimated that lion’s age.

For the past year as a Postdoctoral Researcher for Panthera’s Lion Program, I’ve been investigating lion age determination, known in plain English as: how to age lions. Though lion biologists have long used unique natural markings (like whisker spots, ear notches and scars) to identify individuals, we’ve lacked a precise understanding of how physical appearance changes with age.

Since an animal changes its movement, territoriality, reproduction and other behaviors as it matures, age can provide precious information about an individual animal and the wellbeing of a larger population. To pinpoint the age of an unknown lion that has wandered into your study area is to reveal that animal’s life story while foreseeing its future at the same time. For managers charged with conserving lion populations in balanced ecosystems, age can be a valuable measure of a population’s vital signs.

The key to aging a lion is knowing which physical characteristics change reliably as lions grow. And that requires tracking lions through time, as Panthera’s partners have meticulously done in long-term study sites across southern and eastern Africa. Over the past few decades, in ten different landscapes, cohorts of researchers have carefully located, named, tracked and photographed hundreds of lions as they grew, from their first appearance beside their mothers as wobbly, wide-eyed 1-month-old cubs to their final years as weary and weathered 10 or 15 year olds.

Thanks to our partners’ detailed recordkeeping, I’ve had the privilege of watching these lions grow up before me on my computer screen. Oyayai, Kakori, S93, Cecil…I’ve seen their naps, their meals, their matings, and watched as they raised litters of cubs and lost pride members to poachers. All the while as I flipped through the JPG files of their lives, I ranked their physical features on a sliding scale, from 1 to 5.

After compiling our findings from 228 lions, we found that six traits noticeably change with age. Nose darkness is the most intriguing: lion noses develop pigment with age, morphing from bright pink to mottled grey (no one knows exactly why). Mane growth is the most obvious: males progress from bald cubs to Mohawked teens to mop-topped adults to thin-haired elders. Older lions pick up more scars as they battle for survival, and teeth increasingly stain yellow and wear down as they chew their way through life. And sometimes, a lions’ lower lip sags to signal its ripe old age. Using a combination of these features, we can narrow down a lion’s age into one of four age classes that correspond to different life stages.

So how well can you age a lion? Test yourself at AgingTheAfricanLion.org, our newly launched site with training materials, pocket guides and a self-test to help managers, researchers and wildlife guides boost their skills in aging lions. Improving our understanding of basic lion biology is one of the many steps necessary to properly manage, conserve and protect lions in Africa. Just remember, it’s all in the nose.

Read more about lions and find out what Panthera is doing to protect them.