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Understanding the differences between hibernation, brumation, and estivation can be tricky because there are several species of animals that use these survival tactics when their environment is not ideal. Animals will go through either hibernation, brumation, or estivation to adapt and survive in different environments.
Not all animals experience a dormancy period when their environments become too harsh for survival, and the common reason animals will enter hibernation, brumation, or estivation is when there are limited food sources, they need to conserve energy, or the weather is too hot or too cold for optimal survival.
It is fascinating to see how animals have evolved to adapt to their environmental conditions to survive in their various habitats.
Overview of Hibernation
Hibernation occurs when an endothermic (warm-blooded) mammal enters a state of dormancy, either due to scarce food in cold temperatures or because of biological obligation as a survival mechanism.
How it Works
Hibernation is a survival mechanism that allows animals to conserve energy by drastically decreasing their metabolic rate and body temperature. It allows them to survive in very cold temperatures so that they do not have to migrate or search for food in a warmer place.
Hibernating animals decrease their metabolism to reserve energy, and they become dormant by falling into a very deep state of unconsciousness. Their heart rate and breathing slow down as they enter a state of inactivity and deep sleep.
There are two types of hibernation—facultative hibernation, which happens when animals hibernate because food is scarce due to cold temperatures, and obligate hibernation, which happens regardless of temperature changes. Obligate hibernation works by seasonal cues that the animal responds to rather than stress from poor environmental conditions like cold weather, which will trigger facultative hibernation in some animals.
Which Animals Hibernate?
- Bears
- Squirrels
- Bats
- Hedgehogs
- Prairie dogs
- Skunks
- Deer mice
What Is the Purpose Of Hibernation?
Animals hibernate for different reasons, and factors such as temperature and resources such as food and water availability play a role in an animal’s hibernation. This allows them to use far less energy and survive without drinking or eating for a long time. Most animals that enter facultative hibernation enter a coma-like sleep due to cold temperatures that affect their food and water sources. During hibernation, the animal does not need to consume food or water as it survives on what it has stored from the previous months.
Animals that enter obligate hibernation become inactive every year during the same months and may occasionally wake up and re-enter this hibernation state. Hibernation can last from days to months, with facultative hibernation happening during cold weather conditions when food becomes scarce. The primary purpose of hibernation is to survive during low temperatures or to preserve energy.
Overview of Brumation
Brumation usually occurs in ectothermic (cold-blooded) animals when the temperature drops for extended periods and is mainly seen in reptiles and amphibians because they do not have access to a heat source in their environment. Brumation is often confused with facultative hibernation, which occurs in mammals.
How it Works
Animals brumate when they cannot generate their body heat, as ectothermic animals depend on environmental heat sources to regulate their body temperatures. If the temperature drops very low for a long time, they will brumate and enter a dormant state. In this state, the animal’s heart rate, breathing, and activity levels decrease, and they enter what is described as a dormant or unconscious state.
The duration of the brumation period varies between species, but it can last anywhere from 3 to 6 months. The reptile or amphibian’s lethargic state ends once the environmental temperatures begin slowly warming up.
Which Animals Brumate?
- Fire salamander
- Common garter snake
- Pond slider
- Common frog
- Tortoises
What Is the Purpose Of Brumation?
The primary purpose of brumation is to conserve energy, and the animal will still need to wake up occasionally for food and water. Low temperatures can cause reptiles to brumate to lower their metabolism and survive in cold temperatures, as they cannot control their body temperature on their own. The reptile’s metabolism shuts down, which means that they do not digest any food, and the cold temperatures also affect their digestion.
Overview of Estivation
Estivation (also known as aestivation) happens when an animal becomes inactive in hot, dry environments.
How it Works
During estivation, animals lower their heart and breathing rates while slowing down their metabolic rate to conserve energy during harsh, hot, and dry weather conditions that put them at risk of dehydration. The dry and hot conditions trigger a state of dormancy in the animal, usually during summer, and it can occur in both aquatic and terrestrial animals.
When an animal is estivating, it can quickly be brought back out of its lethargic state, and before an animal estivates, it will go through a similar process as hibernation. Estivation can last for the entire summer to only a few days, depending on the environmental conditions. The animals usually search for a shady and sheltered spot before entering estivation, while others may burrow underground in a watertight layer.
Which Animals Estivate?
- Land snails
- Bogong moths
- California red-legged frog
- East African hedgehog
- Malagasy fat-tailed dwarf lemur
- North American desert tortoises
- Crocodiles
What Is the Purpose Of Estivation?
The purpose of estivation in animals is to conserve energy and survive in very hot or dry weather conditions. Animals will also estivate to stabilize their body organs, which may be compromised during hot weather, and they may go through it to prevent dehydration by slowing down their body functions. They will not be in a deep state of dormancy like brumation or hibernation, but they will go through a similar period in preparation for estivation.
The Main Differences
| Hibernation | Brumation | Estivation |
| Occurs in endothermic (warm-blooded) mammals | Occurs in ectothermic (cold-blooded) animals | Occurs in both endothermic and ectothermic animals |
| Happens in cold-weather conditions | Happens in cold-weather conditions | Happens in hot and dry conditions |
| Can last from days to months | Typically lasts for 3–6 months | Lasts from a day to several months |
| Survive off energy reserves from water and food they have consumed beforehand | Wake up to drink and eat occasionally | Move on cooler days |
Conclusion
Hibernation, brumation, and estivation are all forms of survival for different animals to adapt to extreme environmental conditions. They are the animals’ way of conserving energy and stabilizing their organs during either winter or summer when temperatures can drop very low to the point where food is scarce or due to extremely hot weather.
Hibernation only occurs in warm-blooded mammals under obligate or facultative hibernation, whereas brumation occurs in reptiles and amphibians during cold temperatures and estivation happens during very hot and dry conditions, which helps them survive in harsh conditions.
All three can be a biological response and instinct for the animal due to seasonal changes, and they may prepare for either hibernation, brumation, or estivation every year.
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Image Credit: Salmar, Pixabay (L), Merrimon Crawford, Shutterstock (C), pen_ash, Pixabay (R)
