We commonly picture bears hibernating during the winter, but many animals have adapted to this practice during the hotter months in something called estivation. Similar to hibernation, these animals will lower their metabolism and be able to survive for extended periods of time in this state. Unlike hibernation, estivation is generally much shorter, but both serve to protect animals from extreme temperatures and food shortages. Here’s a list of the animals that hibernate in the summer, as well as their reasons for doing so.
10 animals that hibernate in the summer
Hedgehog hibernation: When the temperature goes above 86 degrees, the hedgehog will lower its metabolism and can live off of fat stores for up to six weeks while curled in a tight, prickly ball.
Hedgehogs are primarily nocturnal and most well known for their ability to roll into a tight ball for sleep and for self-defense. This strategy is dependent on the number of quills available, so many desert hedgehogs that evolved to carry less weight are more like to flee or attack.
This animal, similar to possums and mice, has a natural immunity against most snake venom, and is unaffected by neurotoxins. They’re a common sight in gardens as well, as they eat grubs and other garden pests, making them a favorite for many gardeners.
Lungfish Hibernation: When their habitat gets too hot and dry, lungfish will estivate in moist water beds and secrete a mucus coating that keeps them from dehydrating – they can stay in this state for up to four years!
The Lungfish is often referred to as a “living fossil”, as it’s survived unchanged for nearly 400 years, tracing all the way back to the Triassic period. It’s found in freshwater habitats throughout Africa such as the Zambezi and Congo rivers. As the name suggests, this fish is capable of breathing air through a specialized respiratory system, which highly contributes to its longevity.
It’s also capable of changing its own biological processes, converting its own waste byproducts during estivation from toxic ammonia to much less toxic urea.
3. Desert Tortoises
Desert Tortoise hibernation: These animals spend 90% of their lives underground where they estivate during hot temperatures, as well as hibernating during colder weather.
These dry weather loving Tortoises live in the deserts of the southwestern United States and northwestern Mexico. During the summer, the ground temperatures can reach up to 140 degrees, so they’ve adapted by using their strong forearms and tough nails to dig these underground burrows to hide from the sun during the day.
They’re herbivores, eating grasses, flowers, fruit, and cacti, and these are also their main source of water. They can go up to one year without any fresh water as long as food is abundant, and can last longer when lowering their metabolism like during estivation.
4. Fat-tailed Dwarf Lemur
Fat-Tailed Dwarf Lemur hibernation: This mammal will estivate during the dry season when water is scarce, and can last up to seven months interspersed with brief periods of rewarming called interbout arousals.
The Fat-Tailed Dwarf Lemur is the only primate known to estivate for an extended period of time, and is native to Madagascar. Prior to their estivation, Dwarf Lemurs will begin accumulating fat in their tails by gorging on food during the wet season when fruits and flowers are more abundant.
During this period, their tails can reach up to 40% of their total body weight and survive off of these fat stores for months. They forage in solitude at night, but during the day they’ll congregate in groups of up to five to a tree hole in order to sleep on cushions of leaves.
Crocodile hibernation: During long periods of drought during the summer, the Crocodile will dig out a burrow in the side of a riverbank or lake and settle in for a long sleep that’s quickly reversed the moment the rains come back.
Crocodiles are found in the tropical habitats of Africa, Asia, Australia, and the Americas, normally living near lakes, rivers, wetlands, and even some saltwater regions. They’re cold-blooded and cannot generate their heat, meaning in addition to estivation they’ll also hibernate or go dormant in colder temperatures.
To help them tolerate being in saltwater, Crocodiles have salt glands on their tongues which allow them to secrete excess salt from these modified salivary glands. They also don’t sweat, instead doing something called “mouth gaping” that’s similar to panting in dogs.
Snail Hibernation: During estivation, a snail will hide in its shell and form a layer of mucus that can protect and keep them alive for up to three years!
Snails are a common sight in most gardens and are well known for their shells and slime, with North America having about 500 species of land snails. Not all snails hibernate or estivate, but it generally happens any time the weather is particularly extreme.
During the warmer months when water and food are less abundant, snails will hole themselves up inside of their shells. They aren’t especially social animals, and will remain solitary until they decide to mate, in which case they’ll seek out the first qualifying mate they can find and then part ways after the fact.
7. Gila Monster
Gila Monster Hibernation: To regulate their body heat during the extreme heat of the desert, they’ll burrow in the dirt, and they can store water and nutrients in their fatty tails for these times of dormancy.
Next up on this list of animals that hibernate in the summer is the Gila Monster. At weights exceeding five pounds, the venomous Gila Monster is the largest lizard native to the United States. They’re found in the Mojave, Sonoran, and Chihuahuan deserts of the southwestern US and northwestern Mexico, taking their name from the Arizona Gila River basin where they were first discovered.
Unlike venomous snakes that inject their venom, Gila Monsters chew to allow the relatively mild neurotoxins to move through grooves in their teeth and into the open wound. They spend 95% of their lives in underground burrows, emerging only to feed and occasionally to bask in the desert sun. They may also use their fatty tail to go months between meals.
Salamander hibernation: Like the lungfish, salamanders will cocoon themselves in a protective layer of slime to stave off dehydration to survive prolonged periods of drought. They are able to survive anywhere between a week and a year in the muddy riverbed.
Salamanders are amphibians that, like most amphibians, have permeable skin that makes them reliant on habitats in or near water or other cool, damp places. Some species are fully aquatic, and they’re capable of regenerating lost limbs and other damaged parts of their bodies.
Salamanders are opportunistic predators, meaning they’ll feed on almost any organism of reasonable size. The Japanese Giant Salamander has been known to eat crabs, fish, and even small mammals. All of them have a mucus covering to maintain the moisture they require to respirate, which also makes them very easily impacted by environmental factors such as pollution and drought.
Earthworm hibernation: When soils get dry, Earthworms go into estivation where they wrap their bodies into a tight knot to reduce the amount of surface area exposed to the soil while secreting a protective mucus around themselves.
Earthworms are integral to the environment, as they regulate soil health and aerate the ground to make plants thrive. They respire through their skin, making them perfect candidates to flourish underground. This skin also makes them incredibly sensitive to touch and mechanical vibration.
This allows them to escape from predators but also makes them more susceptible to environmental changes, making them another perfect indicator of the overall health of an ecosystem.
Ladybug hibernation: In the summer, the ladybug’s main source of food (aphids) are decimated by the hot sun, so they’ll enter a state of dormancy in wait for food to become plentiful again.
Ladybugs are generally considered to be useful insects, as many prey on common agricultural pests such as aphids and scale insects. In fact, many species of Ladybug will lay their eggs directly in these insect colonies in order to ensure they have an immediate food source.
They were originally thought to be purely carnivorous because of this. However, further analysis of their diet has shown other items such as honeydew, pollen, plant sap, nectar, and various fungi. The introduction of ladybugs is a common ecologically friendly pest-control method within gardens.
When Ladybugs when they wake up from dormancy, they can still be regarded as pests themselves due to their extreme abundance and ability to find ways into the home.