Mechanism of a bunny thump

Question
Dr. Krempels,

I recently adopted/found an escaped, dying rabbit. He, Winchester, has become a very special addition to my flock. He is very health, active, and quite a character. As a bunny (a macho bunny at that:) he gives warning thumps. I am curious about these thumps. I have read many responses about why bunnies thump but none have addressed the mechanism of this thump (besides the obvious - that he is slamming his leg against the floor).

The force used generates a very strong impact and reminds me of a flea jump mechanism that involves resilin (elastic protein), like stored energy akin to an electric impulse.

Can you please explain, from a biological perspective, how the bunny's back leg can generate such an acute action?

Thank you for reading this and, in advance, for any answer or direction to find the answer you provide.

Regards,
Anton

Answer
Dear Anton,

Rabbits don't have anything like the spring-loaded mechanism of a flea's hind legs, but they do seem to get more "bang" for their thump than would be expected by a simple foot stamp.

I've watched them and wondered about this, too.  I think that they use the same motion for thumping as they use for a very quick take-off to sprint away when they are startled, but they "abort" the run and may instead apply that extra force to the thump.  I'm not sure.  Just speculating.  I don't know of anyone who has actually studied this, but it's an interesting question.  Wish I had a better answer for you.

I'm glad you found Winchester!  He's lucky to have such a caring, observant parent.  :)

Take care,
Dana