That Reptile Blog – Reptile, Amphibian and Exotic Pet Care and Information

Snakes are well known for their abilities to survive long fasts – up to 2 years in some cases – without ill effect.  Working with ball pythons, diamondback rattlesnakes and various rat snakes, researchers at the University of Arkansas have recently shown that fasting snakes slow their metabolisms by up to 80%, and yet continue to grow even when food is withheld for 6 months.

Ball Pythons, the Champion Fasters

The reduced rate of metabolism may explain why many snakes lose little weight when fasting.  Keyed by circadian rhythms (“internal clocks”), ball pythons are notoriously worrisome to pet keepers in this regard.  Most refuse food for long periods of time each year, yet remain in good condition…in fact, the longest-lived captive snake is believed to be a ball python that attained approximately 51 years of age at the Philadelphia Zoo.

Growing Without Eating

The fact that fasting snakes continue to grow suggests that large size confers important survival advantages.  If it did not, precious fat reserves would not be allocated to growth during food emergencies.

Evidence from Zoo Animals – the Gharial

Other reptiles and amphibians seem possessed of similar abilities, although confirmation is lacking.  Fish-eating crocodilians known as Indian gharials (Gavialis gangeticus) are one example.  A group of 8 at the Bronx Zoo ceased feeding in tune with the cool season in their native Pakistan each year for the nearly 20 years that they were under my care.  They fasted for 3 months, but continued to move about and bask, and lost little of their 400-600 pound bulk during that time.

Other Reptile Pets

Bearded dragons and temperate zone reptiles, such as box and Eastern painted turtles, often stop feeding during the winter, even if kept warm.  Bearded dragons usually become largely inactive, but turtles often move about normally.  Despite this apparent use of energy, they lose little if any weight.

Interestingly, at least for turtles, individuals born in captivity usually remain active during the winter if kept warm, while wild-caught specimens typically go off feed for 2-6 months.

Know Your Pets’ Needs

Providing your pet with proper care and a healthful diet is vital if it is to survive seasonal fasts.  Be sure to research the species that you keep carefully.  Please consult our reptile and amphibian care books, and don’t hesitate to write in with any questions you may have.

Further Reading

To learn more about hibernation and fasting periods, please see my article Hibernation in Bearded Dragons and other Reptiles and Amphibians.

The process of hibernation (or brumation) in reptiles and amphibians seems subject to a great many factors.  For example, I have noticed that spotted and Eastern box turtles, and other temperate North American species, vary greatly in this regard.  In captivity, wild-caught individuals usually slow down (activity and feeding) during the winter, even if kept warm and given a photoperiod of 12 hours.  Captive-born animals of the same species most often continue to feed throughout the winter.

Green frogs, garter snakes, musk turtles and others, however, usually stay active if kept warm in winter, even if wild-caught.

A recent email from a colleague brought up the subject of bearded dragons.  His animal becomes lethargic and ceases feeding in October, despite a long photoperiod, and high ambient and basking temperatures.  Most bearded dragons in the US pet trade are several generations removed from the wild, yet the tendency to hibernate persists in some.  Many bearded dragons, however, remain active all year.   I am wondering if what we are seeing is related to the natural range of our pets’ ancestors… perhaps those from certain areas hibernate in the wild and retain this pattern in captivity?

A Request for Help

Internal (circadian) rhythms exert their influence on most animals, and an understanding of their workings is vital from both a pet-keeping and conservation point of view.  I would greatly appreciate being informed of any seasonal changes in activity that you notice among your pets.

Some North American turtles are incredibly cold-tolerant, and are being studied to see if the mechanisms they use might be applied to the possible storage of human organs destined for transplant.  The abstract of an interesting The Journal of Herpetology article is posted at:

http://www.jstor.org/pss/1565569

If you’re looking for general care information on bearded dragons, check out my article: Bearded Dragon Natural History and Captive Care.