View Full Version : Literature Review: Hognoses Thermal Preferences.

09-20-2005, 10:39 PM
Questions often come up about the ideal temperatures for captive hognose snakes. I decided to do a literature review on the thermal preferences of western and eastern hognoses. I first relied on the classic by Dwight Platt, his publication on the natural history of hognoses from 1969. Included in this extensive study, are his findings on the cloacal temperatures of hognoses immediately after capture in the field by hand, and in an outdoor pen in which both shade in full sunlight were available.

Cloacal temperatures of normally active snakes was between 81° and 95 °. No normally active snakes were captured with cloacal temperatures above 96.8°below 68° (early in the morning after emergence from their burrow). The maximum basking temperature of the snakes in the outdoor pen was 90°. The critical maximum temperature was around 105°.

Next I refer to a paper by James Kitchell on the thermophilic and thermophobic responses of different snakes along a thermogradient maintained in an artificial enclosure. The eastern hognoses were maintained in eight-foot long enclosures with temperatures varying from 59° to 113°. For the hognoses, the normal body temperature range,
74° to 99° - average of 89°
After feeding,
91° to 96° - average of 92°
In ecdysis (shedding)
62° to 67° - average of 64°

Although not significant, the average body temperatures for the 24 hour period after feeding was consistently higher than the normal averages. The author supposes that the higher mean body temperature of hognoses correspond with the warmer conditions of their typically upland habitats. The lower temperatures associated with ecdysis may relate to the increased risk of predation, and the advantages of a cool/moist environment that probably facilitates the initial stages involved in casting the skin. Interestingly, heavily parasitized individuals and those injured, generally retreated to the cooler portions of the gradient. This behavior is counterintuitive in my opinion, although this may be explained by the relatively short five day period of experimentation and low sample size (not specified, but probably less than 10 individuals).

My main motivation for this literature review is that I believe there is a consistent problem with amateur herpetoculturists simply not providing enough heat to their reptiles. Although I have seen this problem most prevalent with captive turtles, I believe that any diurnal reptile (referring mostly to the North American native/temperate species) should be provided with a very warm spot for basking. I think too many people underestimate the need for reptiles to reach their proper body temperature. Room temperature alone is clearly not enough. A warm enough area should be provided to the reptile that not only provides enough heat for it to obtain its ideal body temperature, but also account for problems with the snake that may necessitate higher temperatures. These so-called "behavioral fevers" may be needed when the snake's immune system is compromised in times of pathogenic infections and parasitism. My own observations have clearly showed me from these forums that most captive herps do not get the basic veterinary care afforded to other groups of animals. Compound that with the usual total lack of understanding of the effects of parasites on captive herps, especially a group of snakes that tend to be heavily parasitized like the hognoses. Providing the necessary temperatures for a hognose to warm up more than its normal body temperature to fight off possible infection is worth the extra effort when considering that most people will never have their hognoses tested for parasites, and most will not go to the veterinarian because they have the expectation of finding a home remedy on an Internet forum. Platt (1969) states that hognoses have a high normal activity range and a high mean cloacal temperature compared to other snakes. Therefore, I recommend providing basking temperatures that are higher on the scale than normally recommended, 90° to 95°.

These numbers above also showed the need for a proper temperature gradient, so that the snake can get cool when ever it feels the need. Surprisingly to me, not only do hognoses like to get cool when they are trying to shed, but they like to get REALLY cool. Most people can not possibly provide a 62° corner in the snake's enclosure during the summer, but it certainly illustrates the point of providing the ability to escape the heat as the snake sees fit. I have trouble making the recommendation on these forums about using 10 gallons for adult hognoses. There's simply no way to provide a 90° to 95° hotspot and a 75° cool spot only 6 inches away. Therefore, I recommend only the use of 20 gallon tanks because of the necessary need to provide a thermogradient. This also corresponds intuitively with the active foraging movements of the hognose, the larger tank thereby provides more active space for more natural movements.

I generally despise the assumptions made for captive herps just because that same species performs a particular behavior in the wild. With this post, I hope this will elicit some responses from experienced and knowledgeable people (like breeders) who will provide their observations on preferred temperature and how it relates to productivity.

Literature Cited

Platt, D.R. 1969. Natural history of the hognose snakes Heterodon platyrhinos and Heterodon nasicus. University of Kansas Publications Museum of Natural History. 18 (4):253-420.

Kitchell, J.F. 1969. Thermophilic and thermophobic responses of snakes in a thermal gradient. Copeia. 1969 (1):189-191.

09-20-2005, 11:13 PM
Very nice! Hognose is a species I would like to keep one day.

This info really helped.