According to the University of Sydney , crocodile populations that have come across these new pests have been dropping like flies , in some places by as much as 77 percent . the World Wildlife Fund toads have been blamed for mass crocodile deaths in Jamaica . Small Americans mongoose one of the world 's `` worst invaders '' red fox responsible for `` two of mammal extinctions ''
the World Wildlife Fund toads have been blamed for mass crocodile deaths in Jamaica . Small Americans mongoose one of the world 's `` worst invaders '' red fox responsible for `` two of mammal extinctions ''