Text by Colleen O’Hara. Photos by Ken Rosenthal
Have you ever wondered how a duck can tolerate swimming in icy water? Or what happens to wood frogs when the temperature drops and the cold winds blow? Animals have a variety of ways to survive the cold winter months when food sources are scarce and the temperatures dip.
During a recent webinar, Ken Rosenthal, Park Naturalist at Gulf Branch Nature Center, highlighted some of the unique and resourceful ways animals adapt to these chilly winter conditions.
They can hibernate, where their body temperature and heart rates drop. These animals, such as the groundhog, will eat a lot of food going into hibernation and lose up to 37 percent of their weight during this time.
Dormancy is another approach. Reptiles and amphibians may enter “brumation” during the cold winter months, when, similar to hibernation, reptiles shut down their bodies to conserve energy. Snakes and turtles will often stop eating before their metabolism slows so they have time to digest their meal. (Undigested food can ferment inside the body and be deadly.)
Wood frogs, tree frogs, and spring peepers can hide under leaf litter, but can’t dig down into the ground to avoid freezing. “The minute the tips of the toes on tree frog, wood frog, or spring peeper begin to freeze they sense the formation of crystals, and their body starts to move sugar into their vital organs,” Rosenthal said. Wood frogs can freeze to the point where they appear dead but thaw out after about six hours.
Migration is another option. Many migratory birds such as warblers that rely on insects, follow the food. As the days get shorter, birds begin to accumulate fat in their body to get ready for the migratory process.
Water birds that hang around our area during the winter such as geese, ducks, and gulls, have a unique adaptation that enables them to tolerate the snow and ice in “bare feet.” Within their legs is a side-by-side blood vessel pair that helps conserve heat: An artery that carries warm blood to the feet heats the blood in the vein that returns colder deoxygenated blood back to the body.
“That’s how ducks can stand in the snow and paddle in the frigid cold water,” Rosenthal said.
Birds such as mourning doves fluff their feathers to conserve heat and will crouch low over their feet to keep them warm. Other birds, such as black-capped chickadees, survive the cold by changing the amount of heat they generate overnight. They drop their body temperature so they have to use less energy. Their body fat drops from 7 percent at night, to 3 percent in the morning.
Some birds such as the Ruby-crowned Kinglet and the Golden-crowned Kinglet, have a lot of extra fluff and insulation surrounding their bodies. As a result, these small, active birds are able to endure freezing temperatures while maintaining a normal body temperature.
Fish don’t need as much food during the winter because their metabolism has slowed down, and they also don’t need as much oxygen. The same is true for turtles and frogs, which tend to nestle into the mud at the bottom of the pond as the temperature drops.
Terrestrial turtles, such as our eastern box turtles, dig into the ground during the winter, can remain frozen for up to 73 hours and can survive spring floods due to a slowed metabolism.
Garter snakes huddle together in a den (by the hundreds and thousands!) to stay warm, and bald-faced hornets die off except for the queens who overwinter and begin a new colony in the spring. Honey bees also huddle together in the hive. They can maintain a temperature that can be up to 40 degrees warmer than the temperature outside.
For more information and fun facts, and to view the entire presentation go to:
Deep Dive: Wintertime Economics: https://www.youtube.com/watch?v=oAyxUKopKoI.