Flehmen Response: Why Big Cats Pull That Strange Face
- Johan Siggesson
- Jul 24
- 3 min read
What is the Flehmen response?
The Flehmen response is a behaviour where an animal curls back its upper lip to draw scent molecules into the Jacobson's organ, allowing it to analyse chemical signals.
If you have ever seen a lion or tiger curl back its upper lip and appear to be making a strange grimace, you have witnessed the Flehmen response. It may look aggressive or even humorous, but it is actually a fascinating behaviour that helps animals gather information about their surroundings. During my years across Africa and India, I have seen this behaviour many times, particularly during the breeding season when scents carry valuable information.
What is the Flehmen response?
The Flehmen response is a behaviour seen in many mammals, including lions, tigers, leopards, cheetahs, horses and even domestic cats. The animal lifts its head slightly, curls back the upper lip and inhales to draw scent molecules into a specialised organ known as the Jacobson's organ, or vomeronasal organ.
Rather than smelling through the nose alone, the animal is analysing chemical signals that reveal information about another animal's identity, health and reproductive status.
It may look unusual, but it is actually one of nature's most effective ways of reading invisible messages left behind in the environment.
Why do lions use the Flehmen response?
For lions, scent plays a vital role in daily life. Urine, scent marks and even the places where another lion has been lying all contain valuable information.
One of the most common reasons for the Flehmen response is detecting whether a lioness is in oestrus. A dominant male may investigate her scent before deciding whether to stay close and guard her from rival males. It can also help lions recognise members of their own pride and identify unfamiliar individuals moving through their territory.
While photographing lions in the Serengeti, I have often watched males pause after smelling vegetation or the ground before lifting their heads into the familiar Flehmen posture. It is a brief moment that can easily be missed, but understanding what is happening adds another layer to the experience of watching wild lions.
The Flehmen response is not a roar
The Flehmen response is sometimes confused with roaring because both behaviours involve the mouth being open. In reality, they serve completely different purposes.
A lion roar is a vocal communication used to advertise territory, locate pride members or warn rivals over long distances. The Flehmen response is completely silent. It is simply the animal analysing scents and gathering information from the air.
Once you know the difference, it becomes much easier to recognise what the lion is actually doing.
A behaviour worth watching
One of the things I enjoy most about wildlife photography is capturing behaviours that tell a story rather than simply showing an animal. The Flehmen response is a perfect example. It reveals a side of big cats that many safari visitors overlook because the moment usually lasts only a few seconds.
Some of these encounters have inspired my black and white lion prints, where subtle behaviour often becomes more powerful than dramatic action. Whether I am creating fine art wildlife prints, limited edition lion prints or timeless lion wall art, my goal is always to share authentic moments that I have witnessed first hand in the wild.
Final thoughts
The Flehmen response may look like a strange facial expression, but it is actually a remarkable adaptation that helps big cats understand the world around them. It allows them to detect chemical signals that our own senses cannot perceive.
The next time you see a lion lifting its lip after investigating a scent, you will know that it is not growling, yawning or roaring. It is quietly reading one of nature's invisible messages, a small but fascinating behaviour that reminds us just how complex these magnificent animals really are.
