Squirrels are a common sight, often observed leaping between branches or tumbling to the ground from significant heights. It might seem surprising, but these small creatures frequently walk away from such falls seemingly unharmed. Their ability to endure these tumbles is a testament to unique physical characteristics and the physics of falling.
Understanding Terminal Velocity
The ability of a squirrel to survive a fall is largely explained by the concept of terminal velocity. When an object falls through the air, two primary forces act upon it: gravity, pulling it downwards, and air resistance, pushing upwards. As a falling object gains speed, air resistance increases. Eventually, the upward force of air resistance becomes equal to the downward force of gravity, at which point the object stops accelerating and falls at a constant speed, known as its terminal velocity.
For squirrels, their relatively small mass combined with a comparatively large surface area means they encounter substantial air resistance early in a fall. This results in a much lower terminal velocity compared to larger, denser objects like humans. A typical squirrel reaches a terminal velocity of about 10.28 meters per second, or roughly 23 miles per hour. This speed is attained quickly, often within the first three seconds of a fall. In contrast, a human in a free-fall position can reach a terminal velocity of about 54 meters per second, or 120 miles per hour. Because squirrels reach their maximum falling speed so rapidly, falling from the top of a tall tree or an even greater height results in the same impact speed, making the initial height less relevant once terminal velocity is achieved.
Squirrel’s Biological Adaptations for Falls
Beyond the physics of terminal velocity, squirrels possess biological adaptations that enhance their survival during a fall. Their skeletal structure is lightweight and flexible, allowing them to absorb impact more effectively than animals with more rigid bones. Strong muscles and flexible joints further contribute to their capacity to dissipate energy from a sudden stop.
When falling, squirrels instinctively spread their limbs wide, effectively transforming their body into a furry “parachute.” This posture significantly increases their surface area, maximizing air resistance and slowing their descent. Their bushy tail also acts as a balancing tool, helping them orient their body during the fall. This allows them to adjust their trajectory and prepare for a favorable landing, often on their feet.
The Limits of Fall Survival
While squirrels are remarkably resilient to falls, there are practical limits to their survival. Fatal falls, though uncommon, can occur. The type of surface they land on significantly influences the outcome; landing on soft ground like grass or loose soil provides a much greater chance of survival than impacting hard surfaces such as concrete. Obstacles encountered during the descent, such as tree branches or power lines, can also lead to injuries.
A squirrel’s health and age can also affect its ability to survive a fall. Very young, old, or already injured squirrels may be more vulnerable to serious harm. Falls from extreme heights, particularly over 200 feet, can result in severe injuries like fractures or internal damage, despite their adaptations. If you encounter a squirrel that appears injured after a fall, contact a local wildlife rehabilitator. Avoid handling the animal directly, as even injured squirrels can bite; keep them warm, dark, and quiet until professional help arrives.