What Happens To Frogs In The Winter?

Frogs are generally abundant during the warmest seasons worldwide, but they seem to go missing once the temperatures start to drop. Amphibians are incredibly skilled at surviving in various climate conditions, and disappearing during winter is one of their essential survival tactics since they cannot withstand harsh colds. 

Generally, frogs hibernate during Winter and survive by burrowing, freezing, or floating below ice depending on the species. Frogs typically die if they do not hibernate properly, and survival rates primarily depend on the hibernation location, their stored nutrition, predation, and timing. 

Generally, frogs survive through winters by hibernating, using various skills and tactics based on the environment’s conditions and the demands of the species type. Frogs have a wide range of physical abilities, enabling them to hibernate through winter and emerge when temperatures begin to rise again.

Although most frogs survive through winters by preparing in advance and hibernating, there are still a few considerable influences that determine their chances of survival. Join us as we discuss what happens to frogs in winter, how they typically survive, and why some frogs may not survive through the season.

Note: The use of the term “hibernation” to qualify prolonged, ectothermic amphibian rest is a debated topic in the biology community, as many scientists prefer the term “brumation” for frogs. Brumaiton is used to qualify prolonged periods of rest for ectothermic animals. However, due to what readers are searching online, we will use the term “hibernation” this article.

How Do Frogs Survive The Winter?

Frogs survive the winter by hibernating and depending on the species, will burrow underground, freeze, or remain at the bottom of freshwater bodies. Frog hibernation entails slowing down their metabolic rates, partial freezing for some, and using their food reserves in order to survive.

How frogs hibernate depends on the species:

The primary aspect for survival is behavioral suppression, where frogs stop using their muscles and cease movement. All frogs use thermal dormancy during hibernation, where they biologically operate at very low temperatures.

In addition, frogs use the following skills and approaches during winters to ensure their longevity:

  • Metabolic Inhibition: Frogs generally slow down their metabolic rates to the point where there is little to no activity. They will barely breathe during this state, and any necessary oxygen will generally be supplied by their surroundings, such as water or soil. Their hearts may stop beating, and their organs will cease activity temporarily. Since frogs have almost no activity during this time, they do not need much resources or energy to survive. Frogs can stretch out their stored energy and survive for months using this survival tactic. 
  • Partial Freezing: Some frogs (notably tree frogs) can cool down their bodies to approximately 19°F and stay frozen for weeks or months. Some tree frog species can even remain in a frozen state for up to a year. Most tree frogs can freeze between 40% and 65% of their bodies ’ water content, which greatly increases their survival chances. Frogs that use this tactic may appear to be deceased, but this state is temporary. Their hearts, lungs, and muscle movement will cease, enabling them to survive through winters while their internal systems continue essential activity to keep their organs from freezing.

Many North American Tree Frogs can freeze this way. Their bodies defrost as the winter draws to a close and temperatures increase, and they resume normal functionality. These frogs are generally the first to come out of hibernation. However, toads are not freeze-tolerant.

How Do Frogs Prepare For Winter?

Frogs spend most of the year preparing for winter, as the harsh colds and sudden decrease in food sources pose severe risks for their overall longevity and wellbeing. While location and hibernation approaches have a crucial role in frogs’ survival rates, much of their hibernation success relies on preparation prior to winter’s onset. 

Here are ways that frogs prepare themselves for Winter:

  • Creating Nutrient Reserves: The first step of hibernation preparation is stocking up on nutrition in bulk, as this will create a reserve of resources for the frogs during hibernation. This phase typically begins in the Spring, notably once mating and reproduction phases are complete. Frogs will eat thousands of invertebrates, becoming relatively large and plump throughout the year.
  • Finding Locations For Hibernation: Once they have sufficient resources in their reserves, frogs will begin searching for suitable hibernation spaces. The search for hibernation locations typically begins in the Fall. The chosen location will primarily depend on the species type, as well as the available spaces within the frog’s habitat. 

Here is a table of where frogs hibernate depending on the species:

Frog SpeciesHibernation LocationReason for Location
AquaticBelow freezing water Aquatic frogs need direct water contact, and the oxygen levels are reasonably high in cold waters below 39°F
ArborealUnder leaf piles or logs, and at the base of treesTree Frogs typically freeze themselves, but complete freezing and dehydration is inhibited by the excessive production of glucose
TerrestrialUnderground in crevices and tunnels, or under rocks, 3 feet below the frost lineHiding in moist soil below the frost line helps terrestrial frogs avoid freezing which would kill them

Learn more about where frogs hibernate depending on the species on our blog

Do Frogs Always Survive The Winter?

While most frogs hibernate through winters, not all of them survive. Their survival is influenced by predation, their chosen location and their reserves, as they may not have proper locations or sufficient resources to survive such lengthy time frames. Frogs that are unsuccessful in preparing for winter are far less likely to survive until spring.

However, even if a frog has managed to survive such threats, it may still suffer if it has inaccurate judgment post-hibernation. Some frogs may emerge from their hibernation state too soon, and this occurrence is fairly common with many Tree Frog species.

Short bursts of warmth may occur toward the end of winter, which can lure frogs out of hibernation too early. The frog will then be stuck out in the cold and will not be able to survive for long, leading to this occurrence being termed ‘winter kill’. If the temperatures remain relatively steady and slowly begin shifting into spring, the frog may still be able to warm up and continue normal bodily functions. 

Do All Frogs Disappear in Winter?

While hibernating during winter is common for frogs inhabiting North America, Northern Europe, Russia, and Northern Asian regions, not all frog species need to shelter themselves to such extreme degrees worldwide. The need for hibernation generally depends on how cold winters get which is influenced by geographical location and overall climate. 

Some frogs can withstand the winters in their regions, or may use another type of hibernation tactic to spend hot seasons in the Southern Hemisphere called estivation. These regions may not have extreme colds and freezing temperatures during winter, but they may have hot or arid conditions in some seasons instead, which also pose a threat to frogs.

As a result, frogs living in these areas may stay somewhat active in winter, and they may go into a state of estivation during extremely hot or dry seasons. Estivation is similar to hibernation, concerning survival methods and behavioral changes, except that frogs undergo such changes to escape the heat instead of the cold.  

More About What Frogs do in Winter

Amphibians cannot withstand extreme colds, and they can die if they are left exposed to these temperatures (CTNF). Regardless of the area chosen for hibernation based on the habitat and frog species, frogs generally adapt their bodily functions to keep up with the harsh conditions. 

Learn more about what happens to frogs in the winter on our blog: