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Research News: How Snakes Survive and Continue to Grow Despite Food Deprivation

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.




  1. avatar

    Nice blog, always nice to start the day learning something. Also quite jealous you worked with Gharials, I fear the worse for those guys

    • avatar

      Hello Gary, Frank Indiviglio here.

      Thanks for your interest in our blog and the kind comment.

      I apologize for being so long in responding. The delay was caused by a technical difficulty which has now been resolved.

      Yes, that was the experience of a lifetime, no doubt. Apparently the main wild gharial population is still afflicted by a mysterious disease; a much smaller group remains in good shape but, as you say, there’s cause for concern.

      A few years back I had the good fortune of meeting the man who has done more for the species than anyone, famed herpetologist Rhom Whittaker. Originally from NY but residing in India (where he founded the Madras Crocodile Bank) for most of his life, he was here for a conference. He wanted to check out his old stomping grounds so I took him snake hunting. Only an hour outside of NYC, we caught 6 species of snake and 6 of salamander in a single afternoon…definitely had everything to do with his abilities, as I have never had a day like that at that site…or anywhere in NY! He is a real gentleman, truly amazing considering his position in the field, and wrote it off to “good luck”.

      Best regards, Frank Indiviglio.

About Frank Indiviglio

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Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.
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