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How Are Squirrels Able to Climb Trees? Ankles That Rotate

Hind ankles that swivel 180 degrees let them descend head-first. The claws, the tail and the grip that make vertical bark walkable.

By Salma 2 min read Save to Pinterest — opens Pinterest in a new tab
A squirrel descending a trunk head-first, hind feet reversed and gripping the bark
Photo: monsterpong09, Pixabay Content License, via Pixabay
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The remarkable part is not the claws. It is that a squirrel’s back ankles rotate right around, so it can hang from its hind feet and walk down a trunk head-first.

The four parts

featurejob
Reversible hind ankleshang from the back feet; descend head-first
Sharp curved clawshook bark, render, timber, mesh
Low mass, strong limbsvertical movement costs little
Long bushy tailcounterweight, air brake, righting

What they can and cannot climb

surfaceclimbable
Bark, timber, render, brickyes
Downpipes, chain link, fence postsyes
Stucco, rough concreteyes
Smooth sheet metal, wide enoughno
Glass, smooth plasticno

Design the barrier around the two jump numbers

Three metres horizontally, 1.2–1.5 m vertically from standing. A smooth baffle 60 cm or longer works only if nothing sits inside that radius — a fence, a bin, a low branch. The clearance does the work; the baffle finishes it.

Why falls do not matter much to them

Low body mass and high drag mean terminal velocity is survivable, and a falling squirrel splays all four limbs and flattens the tail to slow further, then rights itself to land feet-first. A fall from the canopy onto leaf litter is a non-event. What injures squirrels is landing on paving, a road, or a fence rail — the surface rather than the height.

Flying squirrels take it further

The patagium — a furred membrane from wrist to ankle, held open by a cartilage rod at the wrist — converts the descent into a glide of up to around 90 metres. Same family, same ankles, one extra piece of anatomy.

Common questions

How do squirrels climb so well?

Four things working together. Sharp curved claws that hook into bark rather than gripping it. Hind ankle joints that rotate through roughly 180 degrees, letting the back feet point backwards so the animal can hang from them. Low body mass relative to limb strength. And a long tail used as a counterweight and air brake. The ankle rotation is the one that does the unusual work.

Why can they come down head-first?

Because of that ankle rotation. Descending head-first, a squirrel turns its hind feet completely around so the claws point up the trunk and hook into the bark, suspending the body from the back legs. Most mammals cannot do this — a cat descends backwards or jumps because its ankles do not reverse. It is the single clearest anatomical reason squirrels look effortless on vertical surfaces.

What is the tail for while climbing?

Balance and braking rather than grip. It counterweights the body during turns along a branch, acts as an air brake and stabiliser in a jump or a fall, and helps the animal right itself to land feet-first. It also serves as a parachute of sorts — combined with splayed limbs it lowers terminal velocity enough that a fall from the canopy is survivable.

Can they climb things other than trees?

Almost anything with texture — brick, render, timber cladding, downpipes, stucco, chain link and fence posts. What stops them is a surface with no purchase at all: smooth sheet metal, glass or plastic of sufficient width. That is the principle behind a baffle, and it is why baffles work where spikes, noise and smells do not.

How high can they jump between trees?

About three metres horizontally, roughly nine times body length excluding the tail, and 1.2 to 1.5 metres vertically from standing. Those two numbers decide every piece of squirrel-proofing: a baffle must have nothing within about three metres to launch from, and must sit above the vertical jump from anything beneath it.

Do red and grey squirrels climb differently?

Not meaningfully — both share the reversible ankles and hooked claws. The differences are in weight and habitat preference: reds are lighter and work finer branches in conifers more readily, while the heavier grey is more at home in broadleaf canopy and on the ground. Flying squirrels add the patagium, which turns a descent into a controlled glide rather than a climb down.

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