Reptile & Amphibian Forums

Michael:
The advice you received regarding violating Cal. Dept. of F & G regulations by releasing Ringneck Snakes back into the wild is valid. But from a biological perspective, there appears to be a considerable amount of misunderstanding about the release of native species of wildlife (including snakes) from one population to a distant region where the same species occurs. Such misinformation seems to not only be perpetuated by wildlife agencies and their biologists but perhaps from university sources as well.

There are only two valid reasons that come to mind for not releasing hybrid specimens, or translocating specimens, from one population to a distant region where the same species occurs (in your case the Ringneck Snake). One reasons concerns the introduction of 'non-native' mtDNA. This has the potential of causing problems with possible future research endeavors. The second reason is that when specimens are released into unfamiliar
areas that are likely to be at or near saturation levels of the same species, they are placed at a huge disadvantage and such introduced specimens are not likely to survive. This is true for tranlocating specimens only a few miles from their original home territory but is even more relavant when translocating specimens into areas with completely different sets of enviornomental conditions from the areas the specimens originated. There may be other valid rasons but all others I have heard have little to no biological merit.

For years, many wildlife agencies have been bastardizing fish populutions including many trout populations here in the west. The Peregrine Falcon recovery was facilitated by interbreeding falcons from a number of regional populations and hacking them (releasing) at various regions in the continental U.S. These resultant hybrid offspring led to the species' recovery. The captive breeding and subsequent releases of the Black-footed Ferret and Red Wolf are other cases in point. There are gobs of other examples. Why wildlife biologists and academics are aware of the above examples and do not bat and eye but then get in a panic when the same situation is mentioned for snakes or lizards is a great puzzle.

That being said, I have always objected to the release of one strain a species into another distant region for the philosophical reason of bastardizing the native stocks. Examples are the transplanting of cutthroat or rainbow trout into distant watersheds with a native population of the same species. But once hybridization occurs, in very short order, natural selection quickly weeds out the weak and leaves a population that can successfully cope with existing environmental conditions. This pertains not only to fish, birds, mammals, but to herps as well.

From what I gather, the project you had in mind was out of curiosity but in fact, was rather ambitious. The release situation you now know is clearly not a good option but the original idea of hybridization has merit from a research perspective. However, first things first. Over a period of a few years, you would need to start with learning how to successfully maintain Ringneck Snakes from different populations. There are expenditures of time and money involved for which one needs to plan.

You would need to create a (research) plan and could seek assistance from others more knowledgeable. You would also then need to learn how to effect captive propagation of the differet forms of Ringneck Snakes and a plan on what is to be done with the resultant offspring (such as donate to institutions).

I have undoubtedly not covered all bases but your last step would be to attempt controlled crosses between specimens from different populations. One that immediately comes to mind is a cross between the Regal Ringneck of Arizona and Utah (which can grow to over 30 inches) with a population from Kansas or the east coast which are both much smaller races. You would need to consumate reciprocal crosses. Results from your prior within-population crosses could serve as controls.

Once you reared the resultant hybrid Ringneck Snakes to maturity, controlled reciprocal backcrosses could be made. Detailed records would need to be kept on all stages of these tests to make such a study worthwhile.

Clearly, this was not what you had in mind but nevertheless might give you some idea the manner in which such an investigation might proceed. On a much smaller scale, I am in the same process with crossing different populations of the Rubberr Boa. My situation is not all that different from the one I mention above concerning crosses between different size morphs of the Ringneck Snakes.

Richard F. Hoyer

>> There are only two valid reasons that come to mind for not releasing hybrid specimens, or translocating specimens, from one population to a distant region where the same species occurs (in your case the Ringneck Snake). One reasons concerns the introduction of 'non-native' mtDNA. . . .The second reason is that when specimens are released into unfamiliar
>>areas that are likely to be at or near saturation levels of the same species, they are placed at a huge disadvantage and such introduced specimens are not likely to survive. . . .

>> For years, many wildlife agencies have been bastardizing fish populutions including many trout populations here in the west.

Would a valid third reason be the possible introduction of parasites/disease into an otherwise healthy population? Your example of trout made me think of whirling disease.
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Chris McMartin
www.mcmartinville.com
I'm Not a Herpetologist, but I Play One on the Internet

Chris:
From my understanding of disease/parasite introduction into wild populations, the subject (potential problems) has been blown well out of proportion to the risk they pose. That is why I did not consider this point as a major reason against
re-release of native species into habitat already occupied by the same species.

Clearly the pathogen introduction point should be considered but in the context of each individual situation. And whether the pathogen/parasite is of exotic or native origin is a point to be considered. The former is akin to releasing non-native or exotic species whereas the latter is essentially a non-issue as far as I am concerned. The introduction (accidental) of the West Nile Virus is an example of the an exotic pathogen being introduced. The virus is mainly a bird pathogen but can cross to other groups an even humans but is highly unlikely to cause any species to become threatened with extinction let alone reduced to the point of great concern. But the jury is still out on that situation so I could stand to be in error.

That being said, there literally have been millions upon millions of released individual organisms in the U.S, invertebrates and vertebrates, legal and illegal, including both native and non-native species plus accidental escapes, and yet problems with pathogens/parasites has been minute.

The release of native snakes (or other native species) with native pathogen/parasites is a non-issue as the wild populations have been selected for eons to cope with such organisms.

Richard F. Hoyer

Richard, some species, especially amphibians, may be more susceptible to introduced diseases than others. We can't know for sure, so it's in the best interests of our wildlife to prohibit any release of captive animals into the wild.

It is commonly reported that upper respiratory tract disease in wild desert tortoises was spread due to the release of infected captives:

http://www.tortoise-tracks.org/publications/jacobson.html

Also, a number of viruses and the Chytrid fungus are suspected of killing off large numbers of amphibians around the world. Nothing has been proven yet, but releasing potentially-infected captives into the wild or moving them from one site to another only increases the risks of spreading such a disease and should never be done. In fact, it is recommended that anyone visiting high-altitude amphibian sites in California use bleach to clean off their boots to avoid any chance of spreading the fungus.

http://www.usgs.gov/amphibians.html

The desert tortoise case is an interesting one. As the linked article points out, this disease was observed in the population at Beaver Dam Slope of Utah in the 1970's, where a large number of captives have been released but it did not cause a mass die off at that time or subsequently. The Kern County population suffered heavy losses between 1988 and 1992 but is the die off caused by the introduction of infected captives to this population? The article is unclear about this. The article also points out that "free-ranging desert tortoises with URDS [are] also widespread in the western Mojave Desert of California, around Las Vegas Valley in Nevada, on the Beaver Dam Slope of Utah/Arizona, and sporadically in low numbers in the Sonoran Desert of Arizona."

Yet there is no report of heavy losses in these other populations. The question remains, what killed so many tortoises in the late 1980s to early 1990s in Kern County but not elsewhere? Sure, tortoises with the disease were seen in this population, but sick tortoises are also seen in many other populations, so a direct causal relationship has not been established. Further, the author points out near the end of the article that "Turtles may remain carriers of Mycoplasma for life with recurrence of the disease at some point in time in the future." Clearly the bacterium, although it most likely causes the disease, does not seem to cause the disease in healthy tortoises, and mass die offs do not occur in many areas even though sick tortoises can turn up virtually anywhere within the range of Gopherus agassizzii. Hence the possibility that wild populations of tortoises carry disease-causing pathogens naturally cannot be discounted.

Nevetheless, the author is correct that captive tortoises should not be released into the wild, just to be on the safe side. That said, it is far from convincing that such releases is responsible for the heavy losses that were observed in Kern County. Most of the tortoises that died in this area during the time period in question may have succumbed to other factors, such as drought, malnutrition or other unknown cause(s).

Below I cite an abstract from a recent study of desert tortoise survival:

"Survival of adult Desert Tortoises (Gopherus agassizii) appears related to site-specific variation in precipitation and productivity of annual plants. We studied adult tortoise survival rates at two closely situated, but physiographically different, sites in the eastern Mojave Desert over a nine-year period (spring 1992 to spring 2001). Survival rates were initially derived from population surveys conducted over a three year period and by radio-telemetry monitoring over a seven-year period beginning in 1994. After a period of initial stability, survival rates on the two sites diverged over the study period, and seven-year survival rates estimated from radio-telemetry monitoring were 0.900 and 0.269, respectively. A die-off in 1996 on the latter site appears to have been triggered by a period of drought, which began in the summer of 1995, coupled with a failure of annual vegetation production in 1996. Depressed survival rates on this site were associated with drought conditions during three of four years. Although the decline had the appearance of an epizootic, there were no clinical signs of disease. Relatively short-term drought, combined with little or no annual biomass, appears to have caused severe reductions in tortoise survival. If periods of drought induced low survival are common over relatively small areas, then source-sink population dynamics may be an important factor determining tortoise population densities."

This study again calls into question the role of disease in the heavy losses suffered by the Kern County population in the late 1980s to early 1990s. Before blaming the losses on disease, the real cause(s) should perhaps be sought.

Literature cited

Longshore, Kathleen M., Jef R. Jaeger, and J. Mark Sappington 2003. Desert Tortoise (Gopherus agassizii) Survival at Two Eastern Mojave Desert Sites: Death by Short-Term Drought? Journal of Herpetology, Vol. 37, No. 1, pp. 169–177
THE DESERT TORTOISE AND UPPER RESPIRATORY TRACT DISEASE

Gary:
I concur with one of your points if you are referring to the introduction of non-native pathogens/parasites. But as mentioned earlier, introduction of pathogens/parasites already existing in native populations is a non-issue for the reasons I stated.

As you probably am aware, I am a 'nuts and bolts' type of person and adhere to the position that one should stick to facts or application of basic scientific principles. To rely on unsupported, anecdotal information, perceptions, impressions, and the like is classical junk-science. The need to take the 'precautionary approach' is invariably based of speculative conjecture without supporting evidence and is yet another example of junk-scence.

Let me comment on the following quote: "It is commonly reported that upper respiratory tract disease in wild desert tortoises was spread due to the release of infected captives:"

You are correct in that it is "commonly reported" but when you examine this issue, the original reports I have viewed were stated as speculation. Subsequent citations repeat that speculation with the difference being that changes sometimes occur in word usage to indicate that the original position was stated as fact. This scenario is an example of how certain aspects of scientific endeavors (citing previous reports) goes amok.

A similar example of which you might be aware deals with reports on the diet of the Sharp-tailed Snake (Contia tenuis). A scientific note by Darling (1946) mentioned that of the 20 odd Contia he captured near Corvallis, Oregon, a number of these specimens regurgitated slugs. Not long after, another researcher reported that the Sharp-tailed Snakes contain unusually long teeth suitable for grasping and holding onto slugs. If you read subsequent citations concerning Contia, you will note that some indicate that slugs are reported to be the exclusive prey of Contia. When I read some of those subsequent reports, from a biological perspective that did not make sense. I have demonstrated that Contia consume other prey besides slugs and thus those that mentioned Contia as preying only on slugs were sloppy in their referencing the original information.

This same situation is what also has occurred with the tortoise situation only the extent of the 'overkill' in this situation suggests that vested interests are also at play. Last year I looked into tortoise disease situation and found no hard evidence to indicate the disease originated in captive specimens and then was tranmitted to wild populations. Some of the individuals that have mentioned that point lack objectivity in that they do not mention the more likely, opposite scenario that the disease in captive populations came from infected specimens taken from the wild.

To propose (openly advocate) that captive specimens are the original source of the disease and infected wild populations is tantamount to stating that the disease organisms were created under captive conditions. It doesn't seem to dawn on these alarmists that all existing pathogens and parasites already exist in the natural world and get into captive populations when wild specimens with the disease organisms are brought into captivity.

Another way of viewing this issue is to examine what has occurred when the non-native species, Starling, Nutria, parrots, lizards, snakes, innumerable plant species, invertebrates, etc., were introduced into N. America. Such exotic species were subjected to pathogens to which they had never been exposed. That such pathogens and parasites could have held them in check for some time may have occurred. However, suseptable individuals succumbed and left populations of disease tolerant individuals.

Even the scenario of the release of exotic disease organisms
is likely to be blown out of proportion to existing evidence. When exotic pathogens are introduced, they have the possibility of causing immediate problems as has been the case with the West Nile virus. But eventually, instead of extinction occuring amongst our native species of wildlife (or plants), it is far more likely that natural resistance factors in our native species will eventually produce populations that are tolerant or resistance to the introduced desease organisms.

Richard F. Hoyer

`That being said, there literally have been millions upon millions of released individual organisms in the U.S, invertebrates and vertebrates, legal and illegal, including both native and non-native species plus accidental escapes, and yet problems with pathogens/parasites has been minute.'

The known problems are minute. The data on these impacts are also minute. If we knew what was going on and found that disease transfer wasn't significant, I'd be right with you. But we don't know what's going on because impacts of translocation simply aren't studied on any large scale.

Patrick Alexander

Richard:

I really do appreciate your positive attitude. I just wanted to comment on a couple of points. The first is the introductions of non-native trout which have been carried out by wildlife agencies. I think it is fair to say that if they had it to do over again they would not have taken that path. I believe they meant well but were ignorant of the possible consequences. The other point has to do with reintroductions when the species has been extirpated from a region. Then it is necessary that the reintroduced animals are from a different region. That is the best one can do, there is no other option except to not reintroduce anything. I don't believe these situations (when native population is extinct) can be used as an arguement to justify release of non-native animals into extant populations.

Carl B.

When you look at the MILLIONS of $$ that have been spent to retrieve,breed and repopulate species such as the CAL Condor you can see how misappropriated monies work in beaurocracy. If steps had been taken but a few years earlier the cost would not only not have been as great but several other species(some which ARENT warm and fuzzy)could be saved as well. There are LOTS of problems like this simply because the people making those management decisions havent DONE science in so long that they are literally OUT OF THE LOOP.Only recently have agencies really realized some of the benefits of herptoculturists and other advances that frankly should have been LED by government funding instead of them being so far behind.We all know of the examples of trickle-down technology from say the defense agencies....What COULD be done with studies and monies(both state and federal)is staggering.Sadly,people like Richard are doing the right thing for the right reason pay the price.
Back to the ringneck story though.....should not our history of reintroducing species in itself be a deterrant? There is far more to lose than there ever will be to gain.With the advances in DNA testing though we should all be aware of such studies and be generously providing scientists with samples ad infinitem! Genetic flow can easily be measured in captive situations that already exist rather than picking 2 animals out of a field guide...And one last point, we all seem to keep many of the SAME species(kings,milks,rats,boas,etc)yet there are SO many really neat snakes in the world....those of us that have bred before I challenge you to accept NEW species,NEW husbandry requirements,NEW ideals into captive breeding!Even if they are "just" ringnecks! Jeff

Jeff:
With respect to your comment about ".....should not our history of reintroducing species in itself be a deterrant?", we need to make a distinction between the different types of species introductions that can occur. You are dead on when it concerns some introductions of certain exotic species as is the case of the Starling and similar such instances. Also, the introduction of native N.A. species into regions in which they were not known to occur is also risky with one (of many) case in point being the introduction of the Bull Frog into western states.

But with respect to the case of the Ringneck Snake situation, here the situation is different in that the species was being introduced into habitat already occupied by the species. And in my reponse to Carl's post, I proposed the reasons why such introductions should be of little concern.

Richard F. Hoyer

Carl:
Concerning your first point, you are correct in that our hind sight is 20/20, that unintended consequences have resulted from what originally was good intentions. Yet, that connot explain why state wildlife agencies, now aware of these situations, are continuing to release hatchery rainbow trout of one origin into streams containing a native race of the same species. I suspect that the answer is that the native population is already bastardized so continuing will seemingly not make matters worse.

And it is my current understanding that some agencies are continuing to release non-native Eastern Brook Trout into high elevation lakes in which no native trout existed in the first place.

As to your second point, I understand perfectly. However, when proposals to release herps back to where they have been exterpated, as was the case on a recent threat on the PARC web site, there has been considerable, unreasoned concerns and opposition voiced for such projects even by some professional biologists. Go figure???

And I agree with your third point as well. ("I don't believe these situations (when native population is extinct) can be used as an arguement to justify release of non-native animals into extant populations." But other than the two points mentioned in my original post, from a biolgical perspective, I have never been concerned, one iota, about the release of one or a few specimens of non-native origin into areas containing the same species. This is considerably different from the repeated mass releases of non-native trout over time, a situation that has had the potential of obliterating native trout populations.

Considering the Rubber Boas as an example, releasing one or a few specimens from one region into another region I consider as a non-issue, just as per the Ringneck snake except for the two reasons I mentioned.

My reasons are as follows: The native populations have been selected to survive the specific environmental conditions that exist in their region. Released boas from a region with a different set of environmental conditions are not likely to survive for two reasons. 1. They have to compete without an established home territory in unfamiliar surroundings against a population with established home territories. Secondly, if one or more specific requirements, for survival of the introduced specimens, are not present in the new terrotory, their chances of survival are further diminished.

But for the sake of argument, lets say one or more introduced specimens survive to breed. After dispersal into new surroundings, odds are overwhelming that any introduced specimen will breed with the native boas. Once mature, subsequent hybrids will further mate with native boas and so on. Thus, a steady dilution of the introduced genes will occur by this process. Further dilution of introduced genes will also occur in that genes from the introduced boas that do no promote survival will be selected against in the new environment.

It is likely that 99.99 % of the genes from the introduced and native boa populations are identical. And in very few generation, any non-identical gene alleles from the non-native stock will either be virtually eliminated and those that may have survived would likely be in a heterozygous state and have little to any impact on the native boa population.

Richard F. Hoyer

Richard,

I agree with you that it appears essentially impossible for releasing a few non-native reptiles to have a significant impact on a native population. I think we also agree that it is not something to be encouraged. And I also believe that this concern is a very weak arguement (at best) against the captive husbandry and propagation of reptiles in general.

Let me say a couple things about the fish. I'm most familiar with California. The stocking of high-elevation lakes is a whole new kettle of beans as no trout were native in most cases (and trout stocking is certainly a factor in the decline of some herp species, e.g. Rana muscosa). I don't think they stock any (or very few) brook trout in the high elevation lakes any more, but I think it makes much difference.

In some cases the CADFG seems to be trying to do the right thing, e.g. stocking the correct subspecies of rainbow trout in the Kern River (but I understand there are some technical problems raising the fish?). In other cases, like salmon, I'm not so sure. The situation with the CADFG with regards to fish is much different than for herps. They bring in a lot of money with fishing lisences... They have an establish culture of fish stocking which is very hard to change (for better or worse)...

Regards,

Carl B.

Working in and around this field has again come full circle back to the beaurocracy that self-perpetuates! Fish stocks have been supplemented for years to encourage outdoor activities(right of wrong)and these aquaculture practices have planted the seeds for big-business. Sadly, most of the fish and wildlife budgets for states revolve around supplemental taxes on hunting/fishing gear as well as the direct sale of licenses.Most of the budget goes to self-sustain these endeavors but there is also additional funds that allows for some law enforcement and little research.In the case of my state(MASS)these funds were even FROZEN by the govenor to add to the general coffers until it was found to be illeagal!!So like the practice or not,we are at the mercy of the hunters and fishermen because THEY pay for most of the non-game management as well.Even though we now know the potential impacts on native wildlife. But the practice should never be encouraged to influential minds, I would rather they not intentially change my landscape,thanks,Jeff

Sadly, most of the fish and wildlife budgets for states revolve around supplemental taxes on hunting/fishing gear as well as the direct sale of licenses.

Sadly? I assume you mean because money from other sources doesn't supplement. Surely the money from license sales is best suited to remain within the purview of fish/game offices vs. going into the general funds. After all, the hunters and fishermen are the ones doing a lot of the hunting and fishing.

So like the practice or not,we are at the mercy of the hunters and fishermen because THEY pay for most of the non-game management as well.

In many states, one has to purchase a hunting or fishing license even to pursue non-game species (such as herps)--so it's not exactly an "us vs. them" type situaiton.
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Chris McMartin
www.mcmartinville.com
I'm Not a Herpetologist, but I Play One on the Internet

Also consider that many herpers are fisherman and hunters as well. I partake in both when I can, and I fish every weekend. I know of many others that do as well. Not to say all of them do, but at least a fair proportion do. Andy
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Andy Maddox
AIM: SurfAndSkimTx04
MSN: Poloboy32486@hotmail.com
Houston Herp Key
The Reptizone

Burgundy baby, With your blue eyed soul, You play the hits and I'm on that roll, Capricorn sister, Freddie Mercury, Jupiter Child cry