By Jude Mead

Spring is the time to celebrate more sunshine and warmer days. Spring is also the time when many animals awaken from a long winter’s nap. After spending a season sleeping, they emerge hungry and ready to roam. Making it to spring, however, is not an easy task for some of these animals. According to Jay Kaplan, director of the Roaring Brook Nature Center in New Hartford, there are varying degrees of hibernation. “Some animals go into a state of deep sleep known as true hibernation. They will use less energy to help them survive the winter while others go into what is called a torpor or lighter sleep,” said Kaplan.

Kaplan explained that in a true hibernation the animal’s body temperatures will drop to a state of suspended animation while their heart rate and breathing slows down. During this period they will not wake up even if they are moved. Animals that go into a torpor or lighter state have low heart rates as well, but their body temperature stays high. This is because they wake up periodically throughout hibernation. Any loud noise or movement can rouse them. 

Animals won’t eat or release body waste when in hibernation. They survive on their stored up body fat. Because of this, they may lose up to half their body weight by the time they wake up. “An animal may weigh ten pounds going into hibernation and wake up weighing only five pounds,” said Kaplan.

It is no wonder then why these animals after hibernating for months are hungry and go after backyard bird feeders. Eileen Fielding, director of the Sharon Audubon Center, said that hibernating animals have an internal clock that lets them know when it’s time to wake up. “Most people think it is the rise in temperature and longer daylight hours that triggers their emergence, but it is more their internal clock.” said Fielding. 

According to Fielding, bears come out of hibernation in early April with a huge appetite. “Bears go into a torpor state over winter. They will wake up easily anytime during hibernation, but they will not eat or drink for months so when they fully awaken in spring they have to get their metabolism back to normal. Once they do, they will forage for food anywhere they can because they have lost one third of their body weight while in torpor,” explained Fielding. 

She added that female bears might have extra mouths to feed in spring. “In January or February some females give birth to two or three cubs. They go in and out of torpor in order to take care of them. This means, however, needing more food when they surface,” said Fielding.

Skunks and raccoons may sleep off a spell of bad weather but are not considered hibernators. They can be seen throughout the cold weather season scrounging around for food and water. 

The true hibernators are the ground hog, also known as the woodchuck, and the chipmunk. They appear in late March if not earlier depending on the weather. “Groundhogs enter a deep sleep and their temperature can drop to forty degrees from ninety-nine degrees,” said Fielding. “The heartbeat slows and they survive on their fat reserves. Weight drops to about half their normal size, so needless to say they are starving when coming out of their burrows.” 

Bats winter over in buildings, hollow trees, or caves. Fielding said, “They need a cool and humid environment. This allows their fat reserves to carry them through the cold months. Fat reserves also give them energy in the spring.” 

Most people look forward to the sound of peeper frogs in early spring. Fielding said frogs are amazing cresatures, “Peepers can endure the freezing temperatures by hiding behind loose bark on trees or underneath logs. They are capable of freezing their internal body fluids in order to survive. This acts as antifreeze where ice crystals form in between cells but not inside cells. A partially frozen frog can breathe through skin and have no metabolic needs.” 

 As the weather warms, the frog will thaw and its heart will resume beating at a normal rate. “The process is remarkable. When they do awake the male begins his high-pitched noise that most of us recognize as the first sign of spring. They are active hunters and feed on anything from beetles to spiders,” she said.

There is nothing simple in the process of coming out of hibernation. It takes energy for animals to get their metabolisms back to normal. Some animals may have little energy left after a harsh cold season and must use that energy to find food in order to regain the weight they’ve lost. Understanding hibernation may be important in the longterm survival of these animals.