How do cats survive falls from great heights?

Veterinarians and biologists say that cats’ remarkable ability to survive falls from great heights is a simple and predictable matter of physics, evolutionary biology, and physiology.

“This recent story isn’t much of a surprise,” says Jake Socha, a biomechanist at Virginia Tech University.

“We do know that animals exhibit this behavior, and there have been lots of records of these cats surviving.”

With scientists unwilling to toss cats off buildings for experimental observation, science has been unable systematically to study the rate at which they live after crashing to the ground.

In a 1987 study of 132 cats brought to a New York City emergency veterinary clinic after falls from high-rise buildings, 90% of treated cats survived and only 37% needed emergency treatment to keep them alive. One that fell 32 stories onto concrete suffered only a chipped tooth and a collapsed lung and was released after 48 hours.

From the moment they’re in the air to the instant after they hit the ground, cats’ bodies are built to survive high falls, scientists say.

They have a relatively large surface area in proportion to their weight, thus reducing the force at which they hit the pavement.

Cats reach terminal velocity, the speed at which the downward tug of gravity is matched by the upward push of wind resistance, at a slow speed compared to large animals like humans and horses.

For instance, an average-sized cat with its limbs extended achieves a terminal velocity of about 60 mph (97 km/h), while an average-sized man reaches a terminal velocity of about 120 mph (193 km/h), according to the 1987 study by veterinarians Wayne Whitney and Cheryl Mehlhaff.

Cats are essentially arboreal animals: when they’re not living in homes or in urban alleys, they tend to live in trees.

Sooner or later, they’re going to fall, biologists say. Cats, monkeys, reptiles and other creatures will jump for prey and miss, a tree limb will break, or the wind will knock them over, so evolution has rendered them supremely capable of surviving falls.

“Being able to survive falls is a critical thing for animals that live in trees, and cats are one of them,” says Dr. Jake Socha.

“The domestic cat still contains whatever suite of adaptations they have that have enable cats to be good up in trees.”

Through natural selection, cats have developed a keen instinct for sensing which way is down, analogous to the mechanism humans use for balance, biologists say.

Then – if given enough time – they are able to twist their bodies like a gymnast, astronaut or skydiver and spin their tails in order to position their feet under their bodies and land on them.

“Everything that lives in trees has what we call an aerial righting reflex,” says Robert Dudley, a biologist at the animal flight laboratory at the University of California – Berkeley.

Cats can also spread their legs out to create a sort of parachute effect, says Andrew Biewener, a professor of organismal and evolutionary biology at Harvard University, although it is unclear how much this slows the rate of descent.

“They splay out their legs, which is going to expand their surface area of the body, and that increases the drag resistance,” Prof. Andrew Biewener says.

When they do land, cats’ muscular legs – made for climbing trees – act as shock absorbers.

“Cats have long, compliant legs,” says Jim Usherwood of the structure and motion lab at the Royal Veterinary College.

“They’ve got decent muscles. In that they’re able to jump quite well, the same muscles divert energy into decelerating rather than breaking bones.”

The springy legs increase the distance over which the force of the collision with the ground dissipates, says Prof. Andrew Biewener.

“The impact forces are much higher in stiff collisions,” he says.

“If they can increase the collision time over a longer period that reduces the impact force.

“And a cat’s legs are angled under the body rather than extended downward, like human or horse legs.”

“You’re not transmitting the forces really directly,” says Dr Socha.

“If a cat was to land with its legs directly under him in a column and hold him stiff, those bones would all break. But they go off to the side and the joints then bend, and you’re now taking that energy and putting it into the joints and you’re getting less of a force at the bone itself.”

However, house cats in urban or suburban areas tend to be overweight and in less than peak physical condition, warns Steve Dale, a cat behavior consultant who is on the board of the Winn Feline Foundation, which supports cat health research.

“That detracts from their ability to right themselves in midair,” Steve Dale says.