Digging into the ground, hibernating, and breathing underwater, or clustering together for warmth… are some of the surprising “strategies” that help animals survive the freezing winter months.
While we might just need to put on an extra sweater or adjust the thermostat to stay “warm” through winter, wild animals have their own unique ways of getting through the cold months.
Here are some of the unique “techniques”:
Ground-Dwelling Spiders
Many spider species that live on the ground in North America, such as wolf spiders, survive the winter by digging burrows in the ground, under fallen leaves, or inside logs.
“The temperature difference between the frozen surface and just a few inches below the cover is often surprising,” says ecologist George Uetz, a spider expert at the University of Cincinnati in Ohio.
“Many species of spiders and insects operate in this ‘sub-freezing’ environment, or sometimes just a few degrees above freezing.”
Since spiders are ectothermic animals and do not generate body heat, their metabolic processes slow down as temperatures drop. “However, it is not uncommon to see spiders and insects active on warmer days,” Uetz adds.
Many spider species “weave” egg sacs with multiple layers of silk insulation to protect their eggs throughout the winter. For example, the yellow garden spider lays its eggs in the fall, so the spiderlings cluster together in the egg sac over winter, emerging en masse in the spring.
According to Uetz, some spider species also have a “secret weapon”: On cool autumn nights, they produce special compounds similar to antifreeze to prevent ice crystals from forming inside their bodies. This is a helpful “trick” to survive until spring without freezing.
Turtles Hibernate and Breathe Underwater
Turtles are inherently slow creatures, and as winter approaches, they significantly reduce their activity.
Some species, such as the eastern box turtle, dig burrows and retract into their shells, entering a state of dormancy known as hibernation. They survive by burning stored fat.
Painted turtles spend winter “soaking” at the bottom of the water, helping them avoid freezing even when the surface is frozen. Because the body temperature of these ectothermic animals matches that of the surrounding water, the cold is not an issue.
Typically, these reptiles breathe air, but during winter, they have evolved the ability to absorb oxygen from water and expel carbon dioxide into it.
Jackie Litzgus, a biologist at Laurentian University in Ontario, states: “When ectothermic animals encounter cold weather, they do not need as much O2. Therefore, what they can absorb from the water is usually sufficient for them to get through winter.”
Turtles exchange gases through “specialized” blood vessels near their skin surface, oral mucosa, and even their cloaca – a cavity that serves as both waste disposal and reproductive outlet.
When oxygen becomes extremely scarce, painted turtles and snapping turtles can even switch to an anaerobic metabolic mode. This respiratory process can lead to dangerous lactic acid buildup, but turtles can consume calcium from their shells to neutralize the acid buildup.
Honeybees Cluster and “Generate Heat”
When it gets colder, they cluster together, improving insulation. (Source: National Geographic).
As temperatures drop, European honeybees return to their hives, clustering together and remaining active throughout the long winter months.
Thomas Seeley, a biologist at Cornell University, states: “This is unique; no other insect species can survive winter by warming themselves.”
The worker bees surround the queen, adjusting the composition of the “bee cluster” to fit the changing temperatures. The bees generate heat by contracting and relaxing two sets of muscles used to move their wings when flying.
Seeley explains: “The energy they expend is not to move or do anything else but to generate heat.”
The queen’s spot in the center of the cluster is the warmest and most comfortable, but even the outermost bees do not freeze. As it gets colder, they cluster tighter, enhancing insulation and compressing the area that needs to stay warm.
“The outermost bees pack together to keep temperatures above 50 degrees F [10 degrees C],” Seeley notes. “This helps them survive.”
This “strategy” relies on months of “planning.” During the flower-rich summer months, bees produce and store 90 pounds (over 40 kg) of honey to sustain the hive through winter. They also choose their location wisely, often selecting the top of a hollow tree to create a warm environment.
Chipmunks “Build” Burrows for Shelter
Chipmunks are members of the squirrel family, but unlike their bushy-tailed relatives, you won’t see them out and about all winter. They also do not hibernate throughout the season, unlike moles, which emerge to signal the arrival of spring.
Instead, these small mammals live in complex systems of burrows, tunnels, and “rooms” that they “construct” to connect small holes filled with various nuts, seeds, and other stored foods.
The eastern chipmunk digs burrows near decaying logs or piles of stones, carving out a tunnel leading to their “rooms,” including a “toilet.” (Source: Shutterstock/National Geographic)
Eastern chipmunks spend several days in a state of hibernation, during which their heart rate drops from about 350 beats per minute to “one figure,” and their body temperature decreases from 94 degrees F (34 degrees C) to the ambient temperature of the burrow – as low as 40 degrees F (over 4 degrees C). However, every few days, they wake up to eat and use specific “toilet rooms.”
Snow Birds Fly to Warmer Climates
According to Jill Deppe, Director of the Migratory Bird Initiative at the National Audubon Society, over 70% of “backyard” bird species in the U.S. and Canada are migratory, with many flying south to winter.
“So even if people may not know exactly what species those birds are, they notice that in the fall, their backyards become quieter.”
The Audubon Bird Migration Explorer maps the annual journeys of over 450 migratory bird species to warmer locations – some of which are “quite puzzling.”
The ruby-throated hummingbird weighs as much as a penny, yet on their way to Central America, some must fly over the Gulf of Mexico – a distance of up to 500 miles (805 km) – in just one day.
“They are so light, it seems they can ride the wind,” Deppe says. Meanwhile, some western ruby-throated hummingbirds “break the southern migration pattern.”
“Some species will fly to places you wouldn’t expect,” Deppe notes. “There are quite a few species that actually fly east, so you will see them in backyards in Louisiana or Florida during winter.”
“If it gets cold where you live, raise a glass to the resilient animals that can endure the harshest seasons on their own.”
