Noctivating Hummingbirds and Hibernating Snow Frogs
A hardy hummingbird weighing just 4 ounces, having no insulation down feathers, and requiring twice its weight in daily food survives a freezing British Columbia night. So said a short article in a nature magazine. How was this possible? Ever heard of torpor? Hummers can lower their internal body temperature and fall into a state of hypothermia. By lowering metabolic rate by 95% they conserve energy and are able to survive occasional cold winter nights. They uses 50% less energy when torpid. (Nightly torpor is called noctivation. Longer periods of torpor are called hibernation.)
I sat on the steps of my backyard deck enjoying the warmth of a sunny late October day. My hummingbird feeders were still available for late arrivals from northern latitudes following the sun southward. There at the feeder, as if by magic, appeared a tiny red-throated male. He lingered and fed profusely trying to store enough adipose energy until he could find another feeder, perhaps in Southern Indiana. He would feed as he retreated south until the days grew warmer and were to his liking.
I wondered if he would try to skirt around the gulf coast into Central America or cut across the Gulf to vacation to a land of nectar and sun. I hoped he would make it. Next spring I hoped he would stop by my feeder for a drink in on his way north. I’ll be looking for him and have my feeders waiting.
So, what about snow frogs? Have you ever seen frog prints in fresh snow? I have. Frogs and toads, although on the decline, are trying to hang on in the northern latitudes. Amphibians run the risk of early frosts and occasional severe winters in addition to a toxic environment.
Frogs do not dig down into pond bottom mud, close up shop, and safely hibernate for the winter. Frogs need to breath, and mud like ice has no breathable oxygen. Frogs find a hole, cave or soft dirt near a pond or lake, dig down as far as they can and hope for the best. Their bodies go into a hibernation-like shut down, use less oxygen, and circulate something like anti-freeze solution into their cells.
Melting patches of snow persisted in shaded areas around my backyard pond. Precocious irises poked their emerald heads up through last night’s snow, reaching for the bright warmth of the noon sun. A little green frog stirred beneath a pile of lifeless companions. It sensed warmth at the entrance of his frigid pond-side cave. For some reason most of his companions had not survived the winter. Their lifeless bodies would eventually thaw out and become food for microscopic pond creatures. My amphibian survivor must have had a little extra anti-freeze solvent in its blood. It had been chosen by natural selection to survive the frigid temperatures of winter. It slowly struggled out from under the dozen or so frozen companions to the warm flat stone surrounded by snow on the edge of my pond.
The little frog soon had a few companions on the other side of the pond. One even managed a weak croak. They basked in the sun for a few hours and then as temperatures dropped, retreated back into their cold crypts. No early mayflies yet, maybe tomorrow. One frog crossed over a soft patch of the cold white stuff and left its frozen footprints. How rare. How mind-boggling. How delightful.
If these survivors manage to survive and reproduce this summer, their offspring will be snow frogs too. It’s Evolution in progress, and it’s in my back yard pond. I am honored.
I placed my hand in the clear cold water, where the snow frog had disappeared. Strands of string algae thrived in the icy water that quickly brought intense deep pain to my hand. The Intolerable pain that dominated my consciousness made me admire those tenacious snow frogs all the more.
The faithful give their Deities credit for the “miracles” of humming birds and snow frogs, but I don’t buy it until I get some good evidence.