Temperatures for Newly Imported Newts
By Ed Kowalski
Many species of salamanders and newts are being imported intermittently from various locations in Asia. There is a large amount of controversy surrounding the husbandry of many of these species. Many people seeking advice from various sources on the Internet about thermal requirements for caudate species are told to keep all newt species cooler than 70°F (21°C). As with most generalizations, there is some truth to this, as well as some falsehood.
One of the issues to consider is the accuracy of the thermometer used to check the temperature, as many of the inexpensive thermometers used in the pet trade can be off by as much as three to five degrees (personal observation). A five-degree variation may be the difference between death and life for a caudate. The thermometers that stick to the outside of the glass are particularly poor for monitoring enclosure temperatures, as they can be affected by outside variables such as sunshine and drafts. In all respects, a thermometer that is actually in the caudate's environment is preferred.
Depending upon the exact locality of origin of the caudate (unknown for most imported species), there can be great variation in the animal's temperature tolerances. It is better to err on the side of safety by keeping any species cool. The reason for this is not readily apparent.
There is a long chain of custody of the animal prior to it reaching the hands of the private individual. The chain of custody usually follows these lines: collector to buyer to exporter to importer to distributor to pet store to keeper. The length of time spent at each of these points can vary considerably. However, one can be reasonably sure that the animal has received less than optimal care and feeding at each stop. Consequently, the caudate arrives in the keeper's hands with little to no fat reserves (personal observation). The animals are then usually kept in a warm (> 70°F) environment. The warm temperature speeds up the animal's metabolism, making acclimation more difficult for these already stressed animals. As the last of the fat reserves are depleted, the animal lacks the necessary reserves to stave off disease or forage for food in the enclosure, and death is a sure result. Keeping the caudate at the recommended cooler temperatures and feeding daily with high quality foods will allow the fat reserves to be reestablished, and the acclimation of the caudate can continue.
High quality foods such as wax worms (puncture the skin to aid in digestion), earth worms (chopped or whole), red worms, blackworms, and some of the live/frozen foods available for tropical fish, such as blood worms, are all easily digested and high in fats. The size of the food item and quantity offered will depend on the size of the caudate. In general, offer enough food that the caudate stops feeding after several minutes. When the caudate has stopped actively searching for food, remove all uneaten food to prevent polluting the tank and potentially poisoning the caudate. Also, house new imports separately to prevention the spread of disease and stress from territorial interactions and competition for food.
If the space available prevents the enclosure from being housed at the recommended temperatures, then there are still several options. If funds and space allow the purchase of a used refrigerator, the refrigerator can serve as a "mini cold room". The refrigerator can have the temperature adjusted to be between 65°F and 70°F (18°C to 21°C) and after the temperature is stable, the animals can be housed in the refrigerator. Alternatively, Coleman Coolers® now makes a plug-in cooler with a built-in refrigeration unit. This will allow the housing of caudates during the acclimation period. The major drawback to these options is the lack of viewing opportunities allowed the keeper. However, this is more than compensated by the survival of specimens that are imported in stressed conditions. A daily check of the caudates will ensure enough gas exchange to prevent suffocation.
Depending upon the species, the caudates may be able to adapt to slightly warmer temperatures after acclimation. I do not recommend allowing any of the Asian species to be allowed to exceed 78°F (26°C) for any length of time, as death will probably occur. In fact, many specimens will not do well at temperatures above 75°F (24°C) for long periods of time. However, I have kept several species of Asian newts in the 70-74°F (21°C to 23°C) range for up to six months of the year as part of the breeding cycle. The most notable of these are Cynops ensicauda, Pachytriton brevipes, and Tylototriton shanjing.
[WEBMASTER'S NOTE: For the temperature tolerance of any specific species, please consult the appropriate Species Caresheet. ]
If temperatures approach the 78°F (26°C), make careful observations for any signs of thermal stress. (Remember that the line between the animal doing well and death is a narrow gap at these warmer temperatures). Thermal stress potentially leading to death can have the any or all of the following signs: frenzied swimming, uncoordinated jumping or walking, and lethargy. A sign that frequently occurs shortly before death is rigidity, where the caudate stiffens and stops moving. Rapid intervention and cooling can potentially save the caudate. The cooling should not be severe (for example plunging the animals into an ice bath) but moderate such as immediately cooling the animal by 5 degrees every 10 to 15 minutes until normal behavior resumes or a base line of 70°F (21°C) is reached.
A final point to mention is that, at higher temperatures, an increase in the frequency of feeding is required to maintain an appropriate body weight and fat reserve. Avoiding obesity while fulfilling the required caloric requirements can be a difficult line to walk with many caudates (particularly Ambystomids). If the caudate looks too fat, a decrease in the amount and or frequency of the feedings may be required. Close observations will eventually lead the keeper to the correct path.
References:
Brenner, Fred J.; 1969, The role of temperature and fat deposition in
hibernation and reproduction in two species of frogs, Herpetologica 25(2):
105-113
Sealander, John, A.; West, Boyce W.; 1969, Critical thermal maxima of some
Arkansas salamanders in relation to thermal acclimation, Herpetologica 25(2):
122-124
Wright, Kevin M.; 1996, Amphibian Husbandry and Medicine, In Reptile Medicine
and Surgery, W.B. Saunders Company, Philadelphia
Last edited January 7, 2004
© 2001 Ed Kowalski