Quote Originally Posted by Stefan-A View Post
Well, it would have to be the chickens, since ferrets are obligate carnivores. "Strange" that nobody's worried about what the livestock might cause.
Actually there is concern, at least in more recent history. Cattle grazing in some areas is limited and regulated because it is believed that over grazing has contributed to toad declines, etc. But back to Nerodia and invasive species, not all species have demonstrated an ability to become invasive. Nerodia has, hence the ban on them. Three different species have become established, so it is a very adaptive genus. They are working on extirpating one population now and hopefully will extirpate others. With our serious decline in native frogs, several species of garter that are endangered or threatened, several species of fish that are endangered or threatened, the additional pressure of Nerodia is something we do not need. They were not banned in the state until after they demonstrated their invasive nature.

Their invasive nature may also become a problem in states that natively have Nerodia as non native populations would compete with and possibly hybridize with native (like what has happened in CA with our Tiger Salamanders - most remaining populations are actually hybrids). I expect Nerodia may become banned in the pet trade in many states before too long.