On October 13, the international online journal, Animals published an article by Lepe, et al, entitled Environmental Impact and Relative Invasiveness of Free-Roaming Domestic Carnivores—a North American Survey of Governmental Agencies http://www.mdpi.com/2076-2615/7/10/78
"This the first study to compare the relative impact of free-roaming dogs, cats, and ferrets. It shows differences in how these three animals react to novel environments. For the US and Canada, free roaming cats and dogs meet the definition of an “invasive” species, whereas ferrets do not. However, the way we as a society view these animals, our attitudes and perceptions, may influence how governmental agencies manage and control them."