Exploring The Last Green Valley: Hibernating season is upon us

The calendar still says autumn, but sunrise today revealed a dusting of snow on the cars and driveway. During morning farm chores I had to break up the thin layer of ice that had skimmed over the surface of our horses’ water trough.

When I let the mares out of their warm stalls to lead them to the back pasture, they stopped, stretched and looked back at the barn as if to say, “I think we would rather stay inside today.”

Walking back to the house I saw our resident squirrel family busy carrying leaves in their mouths up into the old maple tree in our yard. That tree has a large hole in one of the branches, perfect for a squirrel nest. No doubt they were making it ready for the cold months ahead.

The chilly morning got me thinking about which of our local mammals hibernate, which ones sort of hibernate and which ones are just fine getting out and about during the cold winter months.

All rely on a warm den of some kind, especially during bitter cold, but their tracks in the snow also tell a story of activity and the ever-present search for food.

The chipmunks that inhabit our yard don’t fully hibernate. They live in an intricate series of tunnels dug below the stone wall that borders our driveway and our neighbor’s property.

I have found the perfectly round, small entrance hole of about 2 inches in diameter at the base of the wall. The hole leads straight down for several inches then branches off horizontally into a series of chambers for sleeping and food storage.

Our resident chipmunks spend the summer and fall running about gathering up seeds and nuts and storing them in their food storage chambers. Our maple, hickory and oak trees provide plenty of readily-available food.

But since chipmunks can’t store enough body fat to see them through the winter without nourishment, they go into a semi-hibernating state or torpor to reduce their body temperature and metabolic rate. They will awaken from time to time to feed on seeds or nuts stored in the food chamber before going back to sleep.

Over the past few years we have more and more reports of black bears in our southern New England region and here in The Last Green Valley. One was seen in Putnam this past summer just down the road from our house.

The black bears in our region will soon be taking their long winter naps.

Unlike the chipmunk, black bear hibernation is a continuous dormancy with decreased heart and metabolic rates. Bears will use their fat stores as they sleep, reduce oxygen consumption by half, and drop their heart rate from 40 to 10 beats per minute. Even with the reduced metabolism, the black bear’s body temperature drops only a few degrees.

In southern New England, where acorns, hickory nuts, beech nuts and other foods are available all fall and into the winter, bears will start hibernation in late November or December.

They will go up to five months without eating, drinking, urinating or defecating. Their hibernation is not as deep as bears in more northern, colder climates and some may even emerge to forage during winter thaws.

Black bears will build their dens in hollow logs, brush piles, rock crevices or under fallen trees. They will excavate their dens under roots of a tree or any convenient structure.

Female black bears breed every second year and give birth to two or three cubs during the denning season in January or February. They will nurse the baby cubs while still in a comatose state.

A few years ago, we had a family of woodchucks residing in and around an old rock pile in the horse pasture behind our house. I am not sure why they moved on, but I haven’t seen them in a few years – perhaps our horses scared them off.

The woodchuck will have a summer burrow usually in an open field with easy access to grass for feeding, and a winter burrow deep enough to keep from freezing, usually in a forested or brushy area protected from snow.

When a woodchuck hibernates, it will breathe only once every five minutes and its heartbeat slows from 100 beats per minute to 15. Its body temperature drops from 95 degrees to only 45 degrees. Unlike the small chipmunk or large black bear, the woodchuck almost completely shuts down its body functions during hibernation.

During the winter season, while walking through our snow-filled horse pasture, I frequently see tracks from various animals.

I especially enjoy seeing small dog-like tracks in the field and along the edges of the stone wall that surrounds it. Sometimes the tracks are in a zig zag pattern as if the animal is constantly exploring beneath the snow and always on the lookout.

Red fox are out and about in winter, and unlike black bears, chipmunks and woodchucks, they do not hibernate. They tend to keep to themselves during fall and early winter and will stay within a two to four mile radius when searching for food. If food is scarce then they’ll expand their search area.

We seem to have plenty of field mice around our property – a favorite meal of the red fox.

The red fox will take refuge during extreme winter conditions and will cut back its activity, taking shelter for a day or two, until the weather and hunting conditions improve.

By January, the female red fox is sprucing up her den, attracting a mate, and pups are born in March or April.

As we move further into December and toward the winter solstice, I’ll be thinking about the hibernating animals snug in their burrows and dens.

During heavy snow storms and deep cold nights I’ll hope the chipmunk’s sleeping chamber is well below the frost line. I’ll be thinking of black bear cubs and hope they’re getting plenty of nourishment from their slumbering mother.

Some winter mornings I, too, will linger in bed and attempt to return to dreamy sleep. The realization of farm chores, hungry horses, dogs and cats will rouse me from my den; like the red fox I’ll be making my rounds, leaving tracks in the snow.

We live in a region breathtakingly beautiful in all seasons. Winter is a magical time of year to enjoy The Last Green Valley National Heritage Corridor. I hope you’ll join me in caring for it and passing it on.

Bill Reid is chief ranger of The Last Green Valley National Heritage Corridor and has lived in the region for more than 30 years. He can be reached at bill@tlgv.org.

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