Newts as invasive species.

[fishkeeper]

As newts and salamanders become more common(as pets), do you think we will have much to worry about invasive species and perhaps legislation? I am aware that T. carnifex has been accidentally introduced.

The tight regs that Washington has made me think. What are the chances of the popular species actually being able to establish viable populations here in the US? I think one or two species might be able to but I'd love more input on this albeit touchy topic.

 

[caudatadude28]

I have thought about that too. I didnt know there were T. carnifex in the U.S. Where are they? Anyways I think most newt species could live somewhere in the U.S. There are so many different climates in the U.S. to fit the different newts. Newts from Europe are from very similar climates to newts in the U.S.

 

[Nathan]

I think more colonizations and invasions are likely. I'm surprised some of the most popular species such as firebellies are not pests already. Most "exotic" pets are tropical, and most exotic pet keepers are in temperate areas, so the risk of establishment is fairly low, but newts being temperate creatures themselves are more likely to become established.

Various tiger salamanders have been introduced outside their ranges in the western US and are causing genetic pollution of native stocks and damaging aquatic fauna. I think this is mostly due to bait bucket releases rather than pet releases, but it goes to show that such things can happen, and can be harmful when they happen.

 

[fishkeeper]

T. carnifex has been introduced in Britain where it did not occur naturally. I think that is also the case with M. alpestris.

Of course, temperature is not the only issue. Some other factors come into play to determine whether creatures can survive in a new environment, let alone breed enough to establish a population. I think one main thing is that firebellied newts probably do not survive very long at the hands of most people anyway.

 

[Nathan]

Sure, temperature is not the only issue, but the strongly seasonal, fairly wet climates of eastern and coastal western North America, western and central Europe, and eastern Asia are quite similar to one another, and the cross-contamination of species among those three areas is very pronounced. Here in the US most of our invasive fish are temperate east Asian, our invasive endotherms European, and our invasive plants and insects a combination of the two. These three areas also have the greatest concentrations of salamander species and salamander keepers. Who knows, there may already be feral populations of red-spotted newts and axolotls somewhere in China.

 

[Jennewt]

Just for perspective, consider the distinction between exotic and invasive. The apple tree in my back yard is exotic, but it's not invasive. There is certainly a potential for newts to become introduced (exotic) species in many places around the world. But I feel that there is only a small potential for them to become invasive - they are unlikely to spread widely or crowd out other species or become so abundant that they could change an ecosystem. There have been a few firebellied newts found in the "wild" in the US. But despite the huge numbers of them imported for many years, no evidence of any breeding population. I'm sure this isn't conclusive evidence that it couldn't happen anywhere, but just one data point to consider. It would be useful to know if the introduced populations of alpestris and carnifex have spread.

 

[gp]

I am actually researching this very topic at the moment. Jen is right in that there are many species that can survive in an environment other than their own but it requires a number of animals to create a viable breeding colony. Some, however, thrive in their new environment. There are numerous examples of this world wide (cain toads being the most famous and invasive).

I am focusing on the potential and existing threat from the non-native members of the Cristatus super-species on our native great crested newt. This makes 'genetic pollution' the main concern as well as displacement. Certainly T. carnifex has been living and breeding in Britain for over half a century. This paper kindly provided by Caleb has some interesting results. http://biology.bangor.ac.uk/~bss024/pdfs/2000/Brede BJLS 2000.pdf

Also, 8 years ago I surveyed a large portion of the north east of England and found numerous populations of M. alpestris. Many populations had clearly spread from a central location often overlapping other introduced populations. Whether there will be a detrimental effect on native newt poulations remains to be seen. As far as I've oberved so far alpine newts are far more willing to inhabit areas that palmate and smooth newts aren't.

It proves to be a more interesting topic the more I learn about it.

 

[fishkeeper]

Graeme: It is interesting to wonder whether a species ability to spread can be predicted by what happened after the last ice age. Some species(crested newt complex, Mesotriton alpestris alpestris, and others...such as those that naturally inhabit Britan) were able to spread from their refuges in the unglaciated portions of Europe(according to the reference I'm using either alpestris did not make it to Britain before it became seperated from mainland Europe or perhaps they died out there). Other species(Triturus marmoratus, Pleurodeles waltl, montadoni etc.) even today are still in the areas that they are thought to have survived the most recent Ice Age(above info, of course, is not my own but I cannot find the reference ATM).

But looking at previous exotics, I don't think spreading ability is so important now as is the ability to form a viable population and compete successfully(even or especially in disturbed areas). Look at Xenopus laevis and American bullfrogs. Xenopus certainly arent good dispersers,(and unlike cane toads they lack any particularly noxious defense) but where they do end up they are able to colonize the habitat readily. Man is adept at moving them around, even accidentally. I think that as far as invasive species go species that are mostly aquatic are the most likely invasives since animals that need both land and water habitats are unlikely to survive in disturbed, channelized habitats.

 

[ezmynd]

My firebellys lived for about 5 or 6 years in my hands. I think for a species to establish tho would be hard by accident because there would have to be enough of a species in a place suitable to its needs where they can find enough mates. Anythings possible tho, look at what happened with the snakehead fish.

 

[SludgeMunkey]

Graeme: It is interesting to wonder whether a species ability to spread can be predicted by what happened after the last ice age. Some species(crested newt complex, Mesotriton alpestris alpestris, and others...such as those that naturally inhabit Britan) were able to spread from their refuges in the unglaciated portions of Europe(according to the reference I'm using either alpestris did not make it to Britain before it became seperated from mainland Europe or perhaps they died out there). Other species(Triturus marmoratus, Pleurodeles waltl, montadoni etc.) even today are still in the areas that they are thought to have survived the most recent Ice Age(above info, of course, is not my own but I cannot find the reference ATM).

But looking at previous exotics, I don't think spreading ability is so important now as is the ability to form a viable population and compete successfully(even or especially in disturbed areas). Look at Xenopus laevis and American bullfrogs. Xenopus certainly arent good dispersers,(and unlike cane toads they lack any particularly noxious defense) but where they do end up they are able to colonize the habitat readily. Man is adept at moving them around, even accidentally. I think that as far as invasive species go species that are mostly aquatic are the most likely invasives since animals that need both land and water habitats are unlikely to survive in disturbed, channelized habitats.

I suspect breeding viability has an influence here. Amphibians that can produce large numbers of offspring tend to take over a biome rather quickly. (Like the American Bullfrog). I think of it as the "Idiocracy" theory- It is not survival of the fittest, it is survival of that which reproduces the most.

 

[SludgeMunkey]

Graeme: It is interesting to wonder whether a species ability to spread can be predicted by what happened after the last ice age. Some species(crested newt complex, Mesotriton alpestris alpestris, and others...such as those that naturally inhabit Britan) were able to spread from their refuges in the unglaciated portions of Europe(according to the reference I'm using either alpestris did not make it to Britain before it became seperated from mainland Europe or perhaps they died out there). Other species(Triturus marmoratus, Pleurodeles waltl, montadoni etc.) even today are still in the areas that they are thought to have survived the most recent Ice Age(above info, of course, is not my own but I cannot find the reference ATM).

But looking at previous exotics, I don't think spreading ability is so important now as is the ability to form a viable population and compete successfully(even or especially in disturbed areas). Look at Xenopus laevis and American bullfrogs. Xenopus certainly arent good dispersers,(and unlike cane toads they lack any particularly noxious defense) but where they do end up they are able to colonize the habitat readily. Man is adept at moving them around, even accidentally. I think that as far as invasive species go species that are mostly aquatic are the most likely invasives since animals that need both land and water habitats are unlikely to survive in disturbed, channelized habitats.

I suspect breeding viability has an influence here. Amphibians that can produce large numbers of offspring quickly tend to take over a biome rather quickly. (Like the American Bullfrog). I think of it as the "Idiocracy" theory- It is not survival of the fittest, it is survival of that which reproduces the most.

 

[fishkeeper]

Yes, most of our caudates are not exactly the most prolific breeders...we have a few exceptions running around in the trade however.(axolotls would be one, but they seem quite specialized in requirements...not many fishless lakes for them to colonize anymore...)

However, another thing to keep in mind is toxicity. One reason Bufo marinus is such a problematic invasive(not to mention its horrifying reproductive abilities and drive) is that it has few predators in Australia, the most significiant being humans wielding golf clubs.

I think another thing to mention is the chances a species will end up in its preferred environment. A montane species is thus much less likely to be an invasive problem in the US. I bet if you collected up enough Pachytriton and took them to a mountain stream(perhaps inhabited by Cascades, yellow legged frogs, or whatnot), they could establish themselves. But what are the chances of that? But lowland species that can survive in such conditions as permanent ponds with fish, and degraded habitats are the most likely to become invasive...since this is pretty much where most dumped newts would end up...in the local park pond.

What saddens me is the frequency I hear people at the pet store or in general saying"When it(usually referring to a turtle) gets too big or I don't want it anymore I'll just take it down to the river and let it go."

 

[gp]

All valuable points. Certainly the area I'm researching at the moment, non-native Triturus species all have the potential to succesfully colonise in the UK. This, however, does not mean that they will. The particular point I'm hoping to discover is whether they have the ability to displace our native great crested newt or suffiently alter it's genetics through hybridisation to irrevocably alter the species. Again, possible but unlikely I suspect.

Of course the underlying issue here is as you say fishkeeper, these animals have to get into their new environment somehow. The "when I'm bored of it I'll let it go" mentality is one of my personal crusades and something I hope to be able to make a significant impact on! Whether people are capable of change, however, remains to be seen!

It is rewarding to see other responible herpetologists and hobbyists expressing similar concerns and trying to identify solutions.

 

[fishkeeper]

NAS - Species List

several records of Cynops phyrrogaster being collected(likely recent releases) as well as Taricha granulosa being transplanted.

I must wonder who released the Golden frog in the Everglades and how that must have been like to find. LOL