Squirrels climb trees fast. They are excellent climbers thanks to their innate agility, sharp claws, long middle digits, and double-jointed hind ankles. Many squirrels climb trees to find food, build nests, and escape predators.
Squirrels’ ability to leap onto a tree and climb up it at top speed is what protects them from predators.
But how do they do it so fast without falling?
In this article, we examine squirrels’ unique climbing skills and find out why robotics engineers are so interested in this topic.
Types of Squirrels That Climb Trees
All squirrels can climb trees. However, tree squirrels and flying squirrels have superior tree climbing skills compared to ground squirrels.
There are over 200 species of squirrels in the world that fall into three categories:
- Tree squirrel
- Flying squirrel
- Ground squirrel
Tree squirrels, such as Eastern gray squirrels, American red squirrels, and fox squirrels, are excellent climbers. They live in trees, using their climbing skill to their advantage every day.
Flying squirrels, including Southern flying squirrels and northern flying squirrels, are also excellent climbers. Their stand-out feature is their ability to glide from tree to tree using their wing-like membranes.
Ground squirrels climb if they have to, but they are terrestrial rodents. They are happiest on the ground or under it in their underground burrows.
What Makes Squirrels Good at Climbing Trees?
Squirrels are good climbers because they use their sharp claws, extra long middle digit, flexible ankle joints, and tail to help them climb with grace and speed.
There are a few adaptations that help squirrels ascend and descend trees without falling:
- Sharp claws
- Extra long middle finger
- Double jointed ankles
- Tail
Sharp Claws
Squirrels’ long, sharp claws allow them to grip into the bark of trees and climb up the vertical surface of tress without falling.
Without their claws, squirrels would not be able to climb.
Squirrels’ Middle Finger
Squirrels have five digits (fingers or toes) in each limb. On their front paws, they have an extra long middle finger. This helps them get a better grip and climb trees faster.[1]
Related: Do Squirrels Have Thumbs?
Double-jointed Ankles
Squirrels’ double-jointed ankles help them climb down trees without falling.
Squirrels swivel at their hind leg ankles when turning around so their hind feet face the sky while their front paws face the ground.
Their back claws grip the tree, making sure the squirrels don’t fall when looking or climbing down.[2]
Tails
It’s not only squirrels’ claws that prevent them from falling for trees. Their tails help them balance.
Squirrels use their tails to communicate, shelter from the sun, and keep warm when it’s cold. Their fluffy tails also stabilize them when they jump from tree to tree.
When squirrels leap from one branch to another, they hold their tails straight behind them. This tail position and the fluffy fur create a parachute effect by increasing the squirrels’ surface areas.[3]
Why Do Squirrels Climb Trees?
Tree squirrels and flying squirrels climb trees to get to their nest. These squirrels build their nests (drays) and dens in the trees. They also rush up trees when evading predators and in search of food. Squirrels depend on trees for their omnivore diet.
Three reasons squirrels climb trees:
- Return To Their Nests
- Evade Predators
- Forage For Food
1. Return To Their Nests
Tree-dwelling squirrels spend more time in their trees than they do on the ground. They sleep and raise their young in their nest in the trees.
Tree squirrels and flying squirrels build their nests, also called dreys, between the branches of trees. They look for tree cavities to nest in ahead of winter. These are called dens.
Commonly found Eastern gray squirrels build their nests in trees at least 20 feet above the ground. They like to nest in trees that provide shelter as well as food. These include oak, red maple, and beech tree.[4]
Tree squirrels enjoy relaxing in the tree tops, especially when it’s hot. Gray squirrels and red squirrels are also known to build their version of summer houses.
In addition to their regular round, enclosed drays, they build light platform-type structures where they can lounge in the shade and escape the heat of the day.
2. Evade Predators
Since tree squirrels feel most at ease in the trees, it’s not surprising that they take to the trees when trying to evade predators.
When tree squirrels spot predators, they make sounds and flick their tails to warn other squirrels. Tree squirrels in the ground that hear and see the alarm are known to run up the trees.
3. Forage For Food
Tree squirrels forages for food in the treetops.
Eastern gray squirrels eat tree buds of oak, hickory, pecan, walnut, and beech trees. They also find ginkgo tree seeds, bulbs, and flowers in the treetops.
American red squirrels eat tree buds, flowers, sap, and bark.
Tree squirrels and flying squirrels eat bird eggs, nestlings, and sometimes even small birds.
Even ground squirrels are known to climb trees in search of food when food on the ground is scarce.
How Do Squirrels Climb Trees?
Squirrels climb by gripping the bark of trees with their claw. They climb fast by using all four limbs to climb. Squirrels use their front limbs to pull and hind legs to push themselves up the tree.
Squirrels’ sharp claws and extra long middle digits in their front paws help them grip onto trees. Their claws stop them from falling off when climbing vertical surfaces.
While climbing trees, squirrels’ tails are positioned downwards, directly behind them. This stabilizes them while climbing.
Should they need to turn around while climbing, they can swivel their hind ankles without moving their feet. Their back feet will face upwards, griping the tree, while the squirrel hangs down.
Once squirrels have reached a branch, they can leap from one branch to another and move through the tree canopy this way.
Why Robotics Engineers Are Interested In Squirrels
Scientists and robotics engineers are interested in squirrels’ incredible ability to leap from branch to branch without falling.
A study by the University of California put squirrels’ quick decision-making and agility skills to the test with an obstacle course. They baited wild squirrels with nuts to leap from different types of perches or branches.[5]
The springier the perch, the more cautious the squirrels were, initially. However, they quickly worked out how to adjust to the springiness and cover the distance to get to the reward.
Squirrels’ ability to learn and implement new strategies to overcome obstacles is of interest to robotics engineers.
There are presently no robots as agile squirrels. Squirrels make split-second decisions about dynamic tasks in complex environments. These are skills robots don’t have yet.
Do Ground Squirrels Climb Trees?
Ground squirrels spend most of their time on the ground or in their underground burrows. However, they can climb trees if they need to.
Ground squirrels can climb trees, but they seldom do.[6]
While they scurry to their underground burrows rather than a tree to evade predators, ground squirrels will forage for food in the trees. When the food on the ground is scarce, they can climb trees to access fruit and nuts.[7]
