I would have to say Pitbull dogs and Bulldogs, and Pitbull or Bulldog type crosses. It has been in such a high demand in my area so much so that the majority of dogs sent to the pound are being killed off once a week or two. I have not been able to find some of my pups a good home.
Add to that, wolves may be spoken of often but they are being hunted off and their homes are being destroyed.
Though sharks are also being overly spoken of. Because of the shark movies, their population has declined a lot too... Gah!