This is a weasel/squirrel/cat thing known as a chichirri. Their tails grow rather large as they age and are used as a defense against predators. They can grow and shed the fur of their tails rapidly and clog the would be predator's throat up with it. They're hunted for their fur, which is very soft and their young are prized as pets. Luckily, the Chichirris' numbers are not under threat from this. They make good, if not rather mischievous pets.

This animation still could use tweaking. I'll drive myself nuts trying to perfect it. >_<