Re: how strong is a squirrel, comparatively speaking?

How strong is a squirrel in a comparative sense?

A general observation in anatomy is that the unit of muscular activity, 
the sarcomere, is basically the same in all animals. This is why smaller 
animals appear to be proportionately stronger. When you measure an 
animal’s strength by its ability to lifts its own body weight, or 
multiples of its own body weight, the smaller animal always wins. Not 
because the small animal’s muscles are stronger but because its body 
weight is smaller. So, the ant can lift 100 times is body weight because 
its body weight is almost zero! (100 times 0 is still 0). The elephant can 
lift more weight in an absolute sense, but can probably only manage a 
little more than its own body weight. Following these principles, a 
squirrel is a small animal. It appears strong, in a comparative sense, 
because it is a small animal.

You also noted that the squirrel was “hanging by its back claws.” That is 
exactly what the squirrel was doing. The claws are effective small hooks 
that can dig into soft wood, or irregular surfaces, and support the 
animal’s body. Squirrels are also able to twist their ankles backward, so 
that they are able to hang head down on a vertical surface – like a garage 
door. Notice how squirrels climb downs trees and sometimes stop at mid 
tree trunk. They are using their claws to hang from the tree bark. Your 
cat, that is chasing the squirrel, also goes down the tree head first, but 
once is starts to go down the cat must go all the way down – it cannot 
stop midway. In fact, the cat can only stop midway on a tree trunk when it 
is climbing upwards, in a head-up posture, so that its claws will support 
its body. 

So, when you saw a squirrel hanging from its hindlimbs, this ability was 
due more to the fact that the squirrel can reverse the direction of its 
hook-like claws than it had to do with the muscular strength of the 
squirrel.