Do Frogs Hibernate?
Updated: July 11, 2020
Many animals survive the harsh temperatures of wintertime in a plethora of different ways. A creature might have specialized body parts or functions like instinctual behaviors that help to keep them alive in extreme conditions. So, how do our amphibious friends, the frogs, survive the season? Do they hibernate?
In short, yes, many species of frogs hibernate. They go into a period of dormancy if the environment they’re in gets too cold, or if there’s a lack of food or water.
However, hibernation is technically a term reserved for warm-blooded animals or endotherms. When exotherms, (cold-blooded animals) like frogs, undergo periods of dormancy, this is known as going into a state of torpor, or brumation, instead.
Let’s look at more information about how this works for frogs below.
While the key aspects are the same, different frogs go about this process in different ways. Some types of frogs will seek out a specific place to stay for the winter. This can be as simple as burrowing into detritus, or involve the frog finding and creating a den in which to lay dormant.
This is also known as a hibernaculum. Frogs must dig their hibernaculum below the frost line, otherwise, they may not survive overwintering within it. It isn’t fully understood if frogs have an instinctual drive to select the safest location for a hibernaculum. It may simply be a matter of chance or natural selection.
Other types of frogs retreat to the warmest part of the environment they’re already in, like those that will simply overwinter at the bottom of the body of water they live in. The American Bullfrog is one example of this. They take in oxygen from the surrounding water.
Some species have even shown the ability to survive after being completely frozen, lauded as being able to “come back from the dead,”. It is thought they can do so because their organs are protected by a natural phenomenon where the high glucose levels in their body act as an anti-freezing agent.
Ice can form under their skin or within their bodies, but if their organs are kept undamaged, the animals’ breathing and heartbeat can completely cease without harm until it is warmed back up and will resume these functions.
Frogs and the Environment
Frogs are aquatic amphibious creatures characterized by their short, tailless bodies that are very important to the Earth’s ecosystem as we know it today. They have many interesting traits aside from their ability to survive winter’s icy clime.
You may have heard of the idea that using frogs humans can somehow tell how polluted an area’s water is. This quality comes from several different features that are unique to frogs. They have semi-permeable skin, which means some of the water from their habitat passes through their skin and into their bodies.
Frogs also possess a special microbiome (a collective term for a colony of tiny, microscopic creatures) that lives on their skin. Both of these things mean that frogs are highly affected by changes in the environment, especially in water cleanliness or if the concentration of the level of pollutants in the water gets too high.
While it might seem like frogs “disappear” in the winter months, we know they’re actually dormant and waiting for spring. However, there is evidence that something much grimmer actually is happening to frogs as a species.
Despite much research being done on the subject, it is not completely known what has been causing frogs and other amphibians to become endangered and go extinct at a much quicker rate than would otherwise be expected. The Global Amphibian Assessment, a study from 2004, declared at least 43% of the world’s amphibious species to be experiencing abnormal levels of population decrease.
It has been suggested that a large reason for the steep decline in frog counts worldwide since the 1950s is due to pollutants harming them or keeping them from reproducing as they normally would. Many dismissed these statistics, believing that these numbers must be a result of other factors.
Habitat loss, disease or fungal infections, or climate change seemed like much more likely causes. Even taking these variables into account, it seems amphibians are still going extinct much faster than they otherwise would, and that this is still occurring in areas where no other explanation is available.
This could be because frogs are unique in requiring both a healthy environment on land as well as in their aquatic homes to thrive due to their metamorphosis throughout their life cycle.
Frogs have statistically been shown to have a larger amount of deformities population-wide since the 1990s. It has been proven that pesticides and other pollutants can have a range of effects including altering frogs’ hormones.
It is theorized that the ozone layer could affect frogs’ abilities to reproduce because the radiation allowed through could cause their eggs to become unviable, even though it may not affect already fully-matured frogs.
Unfortunately, this data seems to indicate that the actions of humans may play a big role in the ongoing extinction of these creatures. Frogs are of vital importance to the food chain. They eat insects, and this keeps the creepy crawlies’ populations within a manageable range. In turn, frogs provide a valuable food source to the larger animals that eat them. (Which then also get eaten by other, often larger, animals. Such is the circle of life.)
Conservation groups have been advocating for more stringent rules surrounding the protection of the habitats of these creatures. This can be a steep uphill battle for many reasons. Considering that even some conservationists refused to believe it was indeed human action causing the mass extinctions to happen.
Even having since realized this mistake, it may be difficult to change the course now, even though it is obvious the stakes are grave. As recently as 2010, it was determined at least 486 species of amphibians are critically endangered.
Other Types of Dormancy
Furthering the list of crazy abilities of these amphibians, even more, we come to another interesting topic called “aestivation.” Frogs in climates where freezing is of little to no concern have another type of dormant state they use to survive hot weather.
This can be a behavior that occurs only when conditions are too harsh for the animal, or an instinctual behavior they exhibit on a set cycle. Other frog species experience aestivation. During this, they burrow into the substrate and cocoon themselves in shed skin or even mucus secretions. They do this to preserve their bodies through environmental changes they couldn’t withstand at their normal fully functioning capacity, like droughts.
During any time of dormancy, a frog’s metabolism must slow down a lot in order to conserve energy. Combining this with the fact that frogs are cold-blooded and therefore also don’t need extra energy to stay warm, we are presented with an animal that can live for many months without food. Some species like the Water Holding frog from Australia can stay in this suspension for up to five years.
Save the Frogs!
So next time you see a frog hopping across the road, a tadpole swimming in a puddle, or any other sign of an amphibious friend trying to grow, please make sure you give them space and help maintain healthy environment they need. You might try looking for local efforts to keep your parks or other wild areas clean. Volunteering, or donating to conservation societies are also valuable ways people can help.
Consider looking into green alternatives to products or habits in your life. This could mean finding products that come in recyclable packaging or making sure you’re recycling correctly. For example, certain plastics aren’t able to be recycled. Plastic bags can also jam recycling equipment lines. Reducing the number of things you throw away is also a big part of conservation efforts. Remember: reduce, reuse. Recycle! Often, little things we do each day can add up to make a bigger difference over time.