I have resigned myself to the fact that there is not going to be an Indian Summer this year… but although my winter clothes are now in my closet and my shorts are put away that is not the craziest thing happening! Animals in the northern hemisphere are beginning to seriously think about hibernating. The fluffy and chunky bears, with all their extra insulation, are getting ready to start their deep energy conserving sleep. But what about animals that don’t have that protective layer of fat …like frogs?
Frogs are amazing animals. They have countless strategies to adapt to extreme climates. In winter, frogs turn to their winter home for hibernation, referred to as a hibernaculum. Some choose a tree for their winter homes while others burrow deep into the ground.
Consider the super versatile Grey Tree Frog which is found in most of North America. It survives down to -8 ⁰C (17 ⁰F) during winter and, those in the more tropical southern climes, tolerate 50 ⁰C (120 ⁰F).
In Wisconsin, where temperatures may drop to below -29 ⁰C (-20 ⁰F) and the ground may be frozen down to 7 feet, how do these little guys not freeze?
Frogs are ectothermic and regulate their body temperature based on external sources, such as sunlight or a heated rock surface. When the weather turns cold, they adapt by slowing their metabolic rate. What is more amazing is that during freezing temperatures, they also trigger their bodies to freeze to the point that they stop their heart beat! But these frozen frogs aren’t dead, not even close, as they have a kind of natural anti-freeze in their bodies. Ice crystals form in their organs and body cavity, but a high concentration of glucose in the frog’s vital organs prevents it from fully freezing. When spring approaches and the frog’s hibernaculum warms up above freezing, this triggers the frog’s frozen body to thaw and come back to life.
Have a look at this cool video of Sir David Attenborough filming a Marsh Frog coming out of hibernation!
Frogs are modern day zombies, which is way cooler than a bear’s winter nap on a full belly!