Keeping a low profile: how big cats achieve invisibility through flexibility
Driving through the African savannah in search of the leopard is an exercise in patience, and often ultimately frustrating. Small wonder it is so, because for this predator to survive, remaining unseen and unheard is of the essence. That is why every encounter with a leopard in the wild is so special.
There are many adaptations that help the leopard to achieve such discretion, and one of them is flexibility. The ranges of rotation of its joints, expecially those of the limb bones, allow it to achieve a remarkably low profile for an animal so big.
A comparison of the articular ends of the limb bones of sabertooths shows us that many of them were just as flexible as their modern relatives. For one of my reconstructions of the sabertooth Megantereon I played with the rotation ranges of the limb articulations in order to show the animal in a stalking pose.
First I examined photos of stalking felines and used the “bone point” method to determine the position and articulation angles of the bones inside the animal. Then I drew the skeleton of Megantereon in a comparable pose, and added the muscles and other soft tissue to complete the external outline of the animal. I have to admit that in order to make the animal more visible in the final rendering of the scene, I set it against a dark green background, which was almost a cruel thing to do since I somehow “blew its cover”… But in the real world, cats sometimes manage to crawl undetected towards its prey against pretty uncooperative backgrounds, sometimes in absolute lack of vegetational cover.
For that illustration I chose a moderate degree of flexion of the limb articulations, so that it was obvious enough that the animal was stalking while keeping its body proportions reasonably evident. But the flexibility of the cats allows them to take things to the extreme, as we were privileged to see in Botswana last september.
There, we encountered a female leopard that was alarmed by the presence of an approaching baboon troop. She took to the cover of some bushes, but on her way had to cross an expanse of flat ground devoid of any cover. And so we saw her crawling with her belly nearly touching the ground, and yet moving surprisingly fast. Funnily, I was instantly reminded of my own pet cat when she was alarmed by the ring of the doorbell and crawled under the bed for safety… A cat is a cat, always.