The short tail of the American bobcat is due to a genetic mutation which did not give the cat any particular benefit in respect of survival but despite that the mutation did not fade away. The reason is probably that the mutation did not hinder survival either. This is despite the fact that the cat’s tail is a useful part of the cat’s anatomy providing balance, for example, when climbing and it also acts as a communication tool amongst domestic cats. That said, the American bobcat, although a good climber, rarely needs to climb (except when pursued by dogs) and therefore the requirement of a tail to improve balance was less pressing in the evolution of this relatively small wild cat species.
An alternative theory is that, like the serval, the short tail evolved over eons because this small wild cat is predominantly a ground dweller and hunter. There is no need for a balancing aid. You’ll find that tree dwelling cats have thick, long tails.
It has to be said to, by the way, that there are other wild cat species within a group of wild cats with shortened tails. These are the Eurasian lynx, the Canada Lynx, the Iberian lynx and as mentioned, the American bobcat. As expected, they occupy a wide variety of habitats and terrains (the bobcat is described as a “habitat generalist”). It cannot be said, as far as I can see, that the evolution of the cat within certain habitats resulted in the development of a shortened tail.
In my opinion, it is probably a simple mutation which happened randomly which did not go away because, as mentioned, it did not have a detrimental impact upon the cat’s survival.
The above are my thoughts which I have to provide because even the best sources on the wild cats do not help me. The well-known book Wild Cats of the World, although providing wonderful descriptions does not explain why the bobcat has a bobtail.
The genetics expert, Sarah Hartwell, writing on her website messybeast.com does discuss bobtail cats but only with reference to domestic cat breeds as far as I can tell. The internet does not provide a decent answer.
It is worth mentioning domestic cat breeds briefly. For example, in Asia the Siamese cat, a street cat, not infrequently has a kinked and/or bobtail. It serves no purpose. It is just there as part of the anatomy of the Siamese cat in Asia. There are other bobtailed domestic cat breeds.
It would be useful if visitors provided their thoughts about why the bobcat has a bobtail. Someone may have a brilliant idea. It has to be supported by an excellent argument though! The argument that the bobcat does not need a long tail for balance does not quite fly for me.