The Migrating and Hibernating Season
“This dropping into a sleep that seems so close to death is one of the strangest adventures of the animal world. The flame of life, for months on end, sinks so low it almost–but not quite–goes out” — Edwin Way Teale, from “Autumn Across America,” Chapter 11 Mystery Sleep
November is the month of animal movement. Migrating birds and some species of bats fly south to escape the cold and scarcity of food. Other animals move into winter quarters to hibernate. Migration and hibernation are nature’s stratagem for these animals to stay alive during a season of scarce food resources. The autumn migration has been going on since early fall, but now picks up with a more hurried pace. Winter is coming.
I love the sight and sound of Canada geese, the ones from faraway northlands, high in the sky in flying V formation, wings making a steady beat to warmer climes for the winter. You can hear their calls, urging each other on. When I was a teenager, their calls evoked a longing for travel, yet these days they bring a tinge of melancholy, the reminder of seasonal change – our slow, yet constant, revolving earth around the sun.
Last November about 40 northern flickers stopped by my yard to glean what insects they could find in my backyard and field. Like the migrating Canada geese, the flickers are northern nesters, moving south in search of food and safety for the winter. I hope they visit again this month.
In our region we think of woodchucks and black bears as our hibernators, though other mammals like chipmucks hibernate but still wake up periodically to feed before slumbering again. Woodchucks are true hibernators, and their body temperature can drop from 99 degrees Fahrenheit to as low as 37 degrees. They rely on their fat reserves to survive the cold during winter’s deep sleep. In his book “Autumn Across America,” Edwin Way Teale writes “the hibernators use up the fat, like an oil lamp turned down low, gradually burns to conserve the heat of life.”
Black bears hibernate but are not true hibernators like the woodchuck. Their body temperature is lower and their heart rate slows during the winter denning season to help them survive cold, adverse weather, and overcome the scarcity of food. The females (sows) give birth to cubs during hibernation with their fat reserves critical to birthing, nursing and bringing forth healthy cubs in the spring.
Some of our region’s bats migrate south where their favored food source, insects, are still available. Other bats migrate into caves where the air temperature is low but stable, there is optimal humidity and few disturbances from sunlight or noise. They’ll enter a state of torpor with heart rates dropping to 25 beats per minute, about one breath per minute, and a near-freezing body temperature. Unfortunately, our cave dwelling bats have been reduced in dramatic numbers by the epidemic white nose syndrome, a moist-air fungal disease. It grows on their nose, face and skin, irritating the bats enough to cause them to awaken during winter hibernation when they are the most vulnerable.
How our cold-blooded species of reptiles and amphibians survive the winter is also an amazing story of survival, but that is for another day. Suffice to stay, a month of very visible seasonal change is upon us again. The quote at the beginning of this column is from Teale’s “Autumn Across America” chapter Mystery Sleep. He closes the chapter with a sentiment I wholeheartedly agree with. “We desired no migrant’s year of one continued summer, no hibernator’s year half lost in unconsciousness. We wanted the whole year, the twelve months complete, the year rounded with spring and summer and autumn and winter, with the variety of all its seasons.”
I too desire a year rounded by all four seasons. I am confident any melancholy feelings evoked by the sight of Canada geese flying south will turn to wonder at the first sighting of fox and coyote tracks in freshly fallen winter snow. Come early spring the dawn chorus of returning songbirds will bring a sense of hope for life renewed, soon to be followed by the warm comfort of a hillside, green with fresh leaves unfurled on a sunny summer day.
We live in a beautiful place called The Last Green Valley where each season, each month, each day of every year, brings another reason to enjoy it, care for it, and pass it on.
Information for this column was gleaned from “Autumn Across America” by Edwin Way Teale, CT DEEP Wildlife information on bats, and the National Wildlife Federation.
Bill Reid is the Chief Ranger of The Last Green Valley National Heritage Corridor and can be reached at firstname.lastname@example.org or by calling 860-774-3300.
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