Squirrels are common and agile creatures often seen darting through trees and across yards. Their remarkable acrobatic abilities lead many to wonder about their resilience, specifically, how they manage to survive falls from significant heights. This intriguing question delves into the unique biological and physical attributes that protect these small mammals from impacts that would be devastating to larger animals.
The Remarkable Answer
Squirrels can survive falls from virtually any height without injury. Their unique biology and the physics governing objects of their size in freefall allow them to endure drops from even hundreds of feet, thanks to specific adaptations that mitigate the impact of a fall.
Mastering the Fall
Squirrels possess several physical attributes that enable their survival of falls. Their small size and light body weight mean they do not generate substantial force upon impact. An adult squirrel weighs between one and two pounds.
When falling, a squirrel instinctively spreads its limbs wide, creating a “splat” or “pancake” shape. This increases its surface area, and along with their loose skin and fur, helps distribute the force of impact over a larger area, reducing potential injury. Their bushy tail also acts as a stabilizer and a makeshift parachute to slow their descent.
Squirrels also have a flexible skeletal structure, including highly flexible ankle joints that can rotate 180 degrees. This allows them to quickly reorient themselves during a fall and absorb shock upon landing, much like a cat. Their strong claws provide excellent grip for immediately securing themselves if they land on a surface like a tree trunk.
The Science Behind Survival
The primary scientific principle explaining why squirrels survive falls is terminal velocity. This is the maximum speed an object reaches during freefall when the force of air resistance equals the force of gravity, preventing further acceleration. For a squirrel, its terminal velocity is low, around 20 to 23 miles per hour (about 9 to 10 meters per second). In contrast, a human’s terminal velocity is much higher, around 120 miles per hour (about 54 meters per second).
This significant difference is due to the squirrel’s high surface area-to-mass ratio. Air resistance, which depends on an object’s surface area, plays a much more substantial role in slowing down a small, light squirrel than a larger, heavier human. A squirrel reaches its terminal velocity quickly, often within the first three seconds of a fall, meaning that falling from a tall tree or a much greater height results in the same impact speed.
Because the impact force is directly related to mass and the speed at impact, the squirrel’s low terminal velocity means it hits the ground with minimal force. This low impact force is something their bodies are well-equipped to handle without sustaining serious injury. While falls from extreme heights could lead to injury if they hit an object on the way down, their biological design allows them to withstand impacts at their terminal velocity.