| | Re: Laotriton question
Thanks for your informative reply. Sorry for my late reply: I had some urgent things to attend to.
In fact I had been searching through both the literature and the internet on several occasions myself and came up with exactly the same as you : next to nothing. To the information you mention, I can only add the remark of Brian Stuart in the discription of this specie that the water in the pools of the Houay Pa Tin stream (Saysamboun ) was quite cold in November. This does not tell me very much exept that it is different from very cold, extremely cold or icecold. Second addition is a measurement of 19°C water-temperature by Gustavo Espellargas in August at the location in Xiang Khouang where the animals that were sold in Europ originate from ( German article by Bachhausen & Espellargas ), but what we need here are water-temperatures during the cold-dry season ( November to February , with December and January being the coldest months).
The information I found on the internet about the climate in the Xiang Khouang province of Laos, is sometimes detailed, but, as you wrote, only gives the air - temperatures on the plateau itself, mentioning that it getts colder in the mountains. The freezing temperatures are usually restricted to the last part of the night and the first hour or so of daylight and do not occur every day. Later on in the day it getts considerably warmer and, depending on how many clouds there are, often reaches temperatures wich Belgians would call warm weather. But it still leaves me guessing about how low exactly the water-temperature dropps in the Laotriton laoensis habitat. I can imagine it to drop under 10°C at times but remain sceptic about near-freezing water-temperatures. In order for the water to gett this cold, the average air-temperature needs to stay around 0°C for a prolonged period of time higher up in the mountains from where the water comes running down.
From you I learn that Laotriton survive such low temperatures ( P.hongkongensis fall unconcious and drown at 2°C). I trust your judgement that they do not suffer from it nor show any signs of stress, so I take back my accusation of cruelty. I will however not try this out on my animals nor will I advice others to do so because I don’t see any need for it.
Detailed information might be found in Somphoutone Phimmachak’s Master’s thesis but chances are that the content will not be translated and not made public, out of fear for misuse by animal-trafficers, especially since she also discovered a range-extension for this specie in the Luang Prabang province.
Another question is: does Laotriton laoensis need these cold water-temperatures to breed succesfully ? Lett me try to explain why I believe that they do not need it but just have to deal with it.
Newts are indeed northern hemisphere animals and indeed even the southernmost species experience cool to cold temperatures. They inherited the same temperature preference for breeding from their ancestors as the more northern species have.
Northern species need, to different degrees, the low temperatures of winter in prepatation to breeding. They are stimulated to breed by rising temperatures in spring and effectively start spawning when the temperature has risen above the threshold-temperature.
Southernmost species however, face a very different climat, to wich they had to adapt. The time of year with temperatures suitable for breeding is not preceded by a period with lower, but by a period with higher temperatures. In adaptation, they are not dependent on a period of low temperatures in preparation to the breeding season, they are not stimulated to breed by rising, but by falling temperatures and effectivly start to do so when the temperature has fallen under the threshold-temperature. A well-know example that answerrs to this model is Paramesotriton hongkongensis, but it is also true for Laotriton laoensis and for an undiscribed Paramesotriton sp. of unknown origin called “Red Warty Newt” by Günter Schultschik (Salamanderland) .
I obtained 2 pairs of adult Laotriton laoensis in March 2006. By using a simplified version of the model, as given in my reply to Brian’s question, the females have laid over 200 eggs each, with a very high fertility-rate, year after year. They are laying eggs now for the sixth winter in a row. The lowest temperature they went trough since they are in my care was 15°C. It was caused by a cold-spell and lasted less than a week. The females stopped laying eggs after 2 days at 15°C, but started laying again a few days later when the water temperature restored to 19°C.
Based on these observations, I believe that L.laoensis do not need temperatures much lower than the threshold-temperature to breed succesfully, but acknowledge that they are confronted with such lower temperatures in their natural habitat and had to find a way to cope with it. Cold-spells play almost certainly a role in their natural selection, eleminating individuals that can not cope from the population.
Paramesotriton hongkongensis females stop laying eggs when the water-temperature dropps too low. My observations suggest that this could also the case for Laotriton laoensis.
If european keepers would keep their Laotriton at temperatures above the threshold-temperature during the breeding season, than I would agree with you that the poor breeding-results in Europ are caused by keeping them to warm. From what I hear and read I know that this usually is not the case. Instead I am convinced that people, in their attempts to make absolutly sure that their animals will breed, disturb them to such a degree that the newts break off any attempt to breed , wich would not happen if they were left undisturbed. Doing nothing apparently is a difficult choice to make.
The method I propose is very easy to understand, very easy to copy and has proven to work just fine for six years in a row. No need to complicate things more than is necessary. There are more than enough problems to solve further down the road. I can only hope that one or two people take me up on this, try it out and report back on their findings. For this year however, it might be a little too late.