The Dog Trainer
10 Year Member!
Platinum Tortoise Club
- Jan 9, 2010
- Location (City and/or State)
- Southern California
Okay. I'll start using the correct term from now on...I think it might be appropriate to bring up here - Turtles and tortoises brumate, not hibernate. I normally try to avoid the "correction police" type behavior, but this discussion bring up exactly why scientists decided it was necessary to create the term brumation to differentiate from hibernation. I know it seems like correcting someone for saying rattlesnakes are poisonous and telling them -no they are venomous. Most of the time we all know what is meant and it really makes little difference. But when the discussion turns to a person afraid of eating rattlesnake meat - it is indeed appropriate to remind they are not poisonous - they are however venomous - so the meat is completely safe, the bite is not!
With this discussion it is therefore appropriate to look at the difference between hibernation and brumation. Many of the myths and preconceptions about allowing a tortoise to brumate comes from our impressions of hibernation.
A hibernating mammal goes into a deep coma-like sleep when hibernating. Nothing disturbs it. It stores fat for the winter and can loose up to 30% of its body weight by the time it awakens in spring. It does not eat or drink at all during this process. Awakening too early can be life-threatening. Not having enough fat reserves can be life threatening. Their body temperature is maintained and their metabolism continues through hibernation. It cannot "semi" hibernate. It is "down for the count" until spring.
A brumating turtle or tortoise does not go into a coma-like sleep. Their body simply slows - breathing, heart rate and metabolism. In fact metabolism can almost totally shut down. Heart rates will drop to 1 beat per minute. Breathing almost stops and in aquatic turtles, the need for oxygen is lowered enough to where all oxygen requirements can be absorbed directly from the water with no need to breath at all. They do not store fat to live off. They store glycogen reserves in their blood and cells to use as the little energy the need to last all winter. A turtle or tortoise will not loose weight during brumation as no fat is being consumed. They should weigh just about the same in spring as they did in fall when starting their brumation. The little weight loss some tortoises have is because of dehydration. A brumating reptile does often need to drink while brumating. The level of brumation will determine this. Brumation is not all or nothing. It is a continuum of degrees of brumation. They can be totally out under the ice until spring thaw, or in a more sleepy, uninterested in food state that still basks in warm spells throughout the winter. When warmer spells come, breathing and drinking increase, but the desire for food seems to be eliminated. Still in a reduced metabolic mode, the glycogen in their system fuels the very slow metabolic needs when more active during brumation. This is a similar condition to aestivation in summer and very hot weather. Chelonians can shut down metabolic needs and survive extremely long periods when conditions are not favorable. Totally unlike hibernation!!
I have watch turtles go through winters and brumate for over 40 years now, since I started building semi-wild environments in my ponds. I have spotted turtles from very cold climates and Suwanee cooters from N Florida where they probably naturally would never brumate. All thrive in my outdoor ponds year round. In Central California where the temperatures are much more mild, yet cold enough to trigger brumation. My spotted never get as cold as their natural climate, and stay a bit more active through winter. My Suwanee cooter get much colder than they would ever experience in a winter in N Florida, and just lay on the bottom most of the winter, coming up to breathe perhaps a few times a month. My oldest Suwanee cooter is 37 as she hatched in 1984 and I've had her ever since. She is thriving and still lays eggs every year. I have never lost a single turtle to brumating through the winter, with about 100 turtles normally in my pond.
So perhaps it is of value to keep in mind our chelonians brumate, not hibernate when deciding what is or is not appropriate and indeed within the range of things brumation allows for.
Thank you for this excellent education.