List of theorems named after non-human animals

If you're willing to stretch slightly further to philosophy, Buridan's Ass paradox is a good one, especially if the ass is mathematically inclined.

In probability, there's the infinite monkey theorem, because apparently monkeys can't read or write but there can be infinitely many of them.

The Pigeonhole principle (sorry Russians, I know you name it after Dirichlet and don't talk about the pigeons) is pretty classic:

If there are $n$ pigeons distributed among $m$ holes, at least two pigeons must occupy the same hole when $n > m$.

Now, this is certainly open to some debate: the theorem is really named after the holes, and not the pigeons. But, if the Bridge of Asses counts...

The Bridge of Asses (Latin : Pons Asinorum) in Euclid. Here, ass does refer to the animal, not reknowned for its intelligence. The meaning is that an ass cannot cross the bridge (by understanding the theorem). The nuance is the converse: If you can't understand the theorem you are an ass and can go no farther in geometry.