Lisenbee: Nature has a way of providing to ensure winter survival
There are a lot of questions about wildlife that cross my desk every year, but there is one that always appears around this time every year. It is how do wild critters manage to survive in brutally cold winter weather, the kind of cold we often have around here every year?
nullWell, nature is a wonderful provider, allowing every species to evolve in its own unique way to survive every single danger it might face within the limits of its habitat. Rabbits are preyed upon by many predators, so that species is prolific when it comes to reproduction. Birds that stay in very cold weather have two layers of feathers to preserve heat and keep out moisture. It is a marvelous system where every need is provided for.
But it also generates a lot of other questions. Ducks, for example, spend an inordinate amount of their time either sitting on water, “dabbling” (dunking their head and upper body while searching for food) under water or actually diving under the water to find food. Yet, when they are once again on the surface they appear to be as dry as we are sitting in our warm houses. How did nature accomplish this feat?
Oil is the key, a very special fine quality organic oil produced by a gland on their back near the base of their tail, to be exact. This oil is so perfect as a waterproofing agent that ducks, by preening each of their outer feathers each day, can remain totally buoyant and impervious to all types of moisture. And these oil glands are present on every species of “waterfowl,” including all ducks, geese, and swans.
Many other bird and mammal species also have oil glands that are used to protect the outer cover of fur or feathers.
River otters have a type of oil that is unique in that it coats the underfur layer and prevents water from reaching the skin’s surface, even when the animal dives deep after a tasty trout. And beaver have a similar oil that coats all three layers of fur that beaver have been blessed with.
Both of these mammalian species can go swimming in icy cold water and emerge to the even colder air without displaying any of the symptoms of cold such as shivering that other animals might exhibit.
Virtually every bird species has some type of oil gland that enables them to preen and “dress” their feathers and therefore keep them in good condition. As long as they have an adequate amount of quality food these birds can usually survive.
The food inside their body generates useful heat as the digestive system breaks it down, and the well-oiled outer feathers retain the heat in a very efficient manner.
Many fish species often have a very difficult time during the coldest part of the winter. Being naturally cold blooded, their metabolic rate naturally slows as the water temperature drops. They remain in either a semi-dormant state or exhibit lethargic characteristics until the warmer sunshine of spring and summer once again warms their habitat.
In some situations, the fish inhabiting a body of water do not survive a really bad winter. If the ice cover is thick enough and there is no other source of oxygen, then the water can actually become so depleted of this important substance that the inhabitants will simply die of asphyxiation.
There are several such ponds on the High-Tor Wildlife Management Area, and I do not believe they are even stocked by the state DEC any more because of this reoccurring problem.
Other fish species must remain very active in all weather and water conditions. Predatory species such as steelhead or salmon forage actively for food throughout the winter. Many steelhead actually move into streams and rivers, fighting the force of flowing water in addition to feeding.
Most of their food during this time consists of salmon eggs deposited during the fall by spawning Chinooks and coho salmon. These eggs are extremely high in protein and carbohydrates, both essential for the steelhead’s survival.
In western New York, the frost can penetrate over three feet into the earth during an extremely cold winter if there is no insulating cover of snow. So, if the ground is frozen solid for three feet how does a tiny critter such as a salamander, snake, frog or chipmunk survive? Well, scientists have recently discovered that some frogs have a unique type of antifreeze in their circulatory systems. When everything else around them is frozen, they are not.
Snakes, salamanders and other small reptiles, amphibians and lower life forms are suspected of having similar substances in their systems. And, both snakes and salamanders usually enter their hibernation dens with food in their digestive systems.
As their body functions slows and they enter the dormant state the digestive actions also slows but does not stop. The food, as it is digested, generates enough heat energy to maintain their spark of life. And winter mortality rates are known to increase dramatically among these species when the warmth of spring is noticeably late in arriving.
The chipmunk is another matter. It is a mammal, and it is also a true hibernator. When winter’s cold grips the land, chipmunks move into their grass and fur lined dens and simply take an extended nap of sorts.
Of course, their body functions slow dramatically during this extended snooze period. Their heartbeat rate drops from around 130 beats per minute to less than 10, just enough to maintain life. Researchers have actually picked up a hibernating chipmunk, handled it, and returned it to its bed without waking or otherwise disturbing it.
Chipmunks, along with most hibernators, do not sleep nonstop through the winter months. They often wake up for a day or two every now and then. Chipmunks spend their waking hours feeding on seeds and nuts they stored during the summer and fall months, filling their stomachs full before returning to bed.
Other hibernators like woodchucks may feed, or they might just take a stroll around the neighborhood if the snow is not too deep and it is not too cold outside. Then, it’s back to bed until conditions outside improve.
Historically in the Finger Lakes and surrounding areas, the coldest part of the winter falls during the last week in January and the first two or three weeks of February. Immediately after this period ends, some wildlife species become very active.
Great horned owls will often begin brooding eggs during the last weeks in February and never later than the second week in March. And skunks will start looking for a mate during the same period, which is why there is often the distinct odor of that species near highways before the official arrival of spring.
Len Lisenbee is the Daily Messenger’s Outdoor Columnist. Contact him at firstname.lastname@example.org