Frog Hibernation

January 11, 2024

Question: Is it true that frogs hibernate during colder times of the year?

Answer: Black bears aren’t the only wildlife species in California that hibernate in winter months. There are 27 species of native toads and frogs in the state and many hibernate, whether in water or on land. Mountain yellow-legged frogs are a good example. To escape frigid weather, the frogs take shelter in underwater rock crevices and submerged vegetation located in deep pools, which are less likely to freeze over.

Elevation plays a big role in what time of year this happens, with frogs at higher elevations having longer hibernation periods than those at lower elevations. Once the frogs find a perfect location, they can remain there throughout winter. During hibernation, the frogs heart rate and metabolism slow enough that the animals don’t require food.

A common misconception is that hibernating frogs bury themselves in mud at the bottom of a pond or stream. But unlike a hibernating turtle, frogs would suffocate without access to oxygen-rich water.

Terrestrial frogs normally hibernate on land, burrowing deep into the soil and safely below the frost line.

Starting to think these questions are now being answered by AI.  So I asked AI the question and frankly I like it's answer better:

Yes, it is true that many frog species hibernate during colder times of the year. Frogs, being ectothermic (cold-blooded) animals, cannot regulate their body temperature internally and are thus greatly affected by the temperature of their environment.

During hibernation, frogs enter a state of dormancy which allows them to survive in extreme conditions. The way they hibernate can vary depending on the species and their habitat:

1. **Aquatic Frogs:** Some species, like the common green frog, hibernate underwater. They lie on top of the mud or partially bury themselves, but they need to be near oxygen-rich water. They can absorb oxygen through their skin, allowing them to "breathe" while hibernating.

2. **Terrestrial Frogs:** Species like the wood frog have a more remarkable approach. They can survive being partially frozen. In the fall, they begin to accumulate urea and glucose in their tissues, which act as antifreezes, preventing ice from forming inside their cells, which would be lethal. Instead, ice forms in the body cavity, around the organs, and under the skin, but the frog's vital organs stay protected due to these antifreeze compounds.

During hibernation, a frog's metabolic processes slow down significantly, and it survives on stored energy reserves. This state of reduced physiological activity allows them to survive until the environment becomes suitable again for active life.

But unlike a hibernating turtle, frogs would suffocate without access to oxygen-rich water.

So, a hibernating turtle will not suffocate without access to oxygen-rich water? What does that mean? Maybe I need to consult ChatGPT to parse this sentence...

Haha the truth is stranger than fiction, I believe the technical term is "cloacal respiration"

But unlike a hibernating turtle, frogs would suffocate without access to oxygen-rich water.

So, a hibernating turtle will not suffocate without access to oxygen-rich water? What does that mean? Maybe I need to consult ChatGPT to parse this sentence...

But unlike a hibernating turtle, frogs would suffocate without access to oxygen-rich water.

So, a hibernating turtle will not suffocate without access to oxygen-rich water? What does that mean? Maybe I need to consult ChatGPT to parse this sentence...

It's mostly accurate. The key word is "oxygen-rich". Hibernating frogs always need oxygen: they'll die in anoxic water pretty quickly. However, many turtle species can hibernate for months in nearly anoxic conditions.

Source: I worked with Cascades and Sierra Nevada yellow-legged frogs, and western pond turtles, on the Lassen National Forest for many years. 

Interesting! Thanks for the additional info.

But unlike a hibernating turtle, frogs would suffocate without access to oxygen-rich water.

So, a hibernating turtle will not suffocate without access to oxygen-rich water? What does that mean? Maybe I need to consult ChatGPT to parse this sentence...

I have no idea what native turtles do when a lake is completely frozen over, but one time a small lake in Shasta County had frozen over. I had hiked into it to fish trout. One tiny little section in a pocket was not frozen so I went there to make some casts. The lake is in a deep canyon and the bottom is all decomposed granite. As I'm fishing, I noticed these odd rocks on the bottom. Well, one of the rocks detached from the bottom and very slowly ascended to take air and return very slowly to the bottom. Every Western Pond Turtle had congregated right there at that little open spot to take air when needed.

On the frog subject, Bullfrogs hibernate for sure. I was clearing out a tiny seasonal drainage one time of leaf litter in the winter. It was very waterlogged and a cluttered mess. I got to a flat spot and as I'm pulling oak twigs and leaves, I started pulling out big Bullfrogs. I was very surprised. At the bottom, about 150 yards away was a good sized pond. I guess that they had gone up the creek when it got cold and burrowed into the leaf litter as it would be the warmest spot and it would be oxygenated when flowing.

We live with a state vernal pools refuge over our back fence.
Summer and fall are always dry but when the rains start and the pools fill the little toads burrow out and the chorus begins. Loudest thing you have ever heard for the first few nights then you get used to it. Look forward to the concert every winter.
And apparently they have enough water because the toads started singing tonight and probably won't stop until May or June.