Ecology is the study of living organisms and how they interact with the environment and other organisms.

• Functional relationships and interactions between organisms and environments
• When the link is made between the organism and the environment, the science becomes ecology

Winter Ecology explores the natural processes and phenomena of organisms in winter environments.

• In some regions, winter is the principal architect of life-form and habitat.
• At higher elevations and higher latitudes, winter is the season of chilling energy deficits that demand the most conservative of physical and physiological adaptations in plants and animals.
• Those geographic areas are where winter temperatures are low enough to elicit consistent and predictable adaptive responses from terrestrial and aquatic organisms ‹ where snowcover is of sufficient duration to be an integral part of the environment and is important enough to make a difference in the overwintering success of the plant or animal

Winter Ecology and Energetics

• Winter is a season of decreased energy - decreased solar, thermal and nutritional energy
• Winter is an evolutionary challenge -- successful organisms balance trade-offs of their energy supplies with the necessity to live and reproduce

Winter ecology studies:

• stresses that winter places on organisms and how this determines their energy use
• evolutionary solutions providing the balance needed to meet the energy demands of survival specific examples of adaptations in organisms

Humans, as organisms, experience interactions with their environment and can use their own bodies and minds to learn about the stesses of winter that all other organisms experience.

• Use your own body to test equipment and clothing every time you go out in the field.
• Take the time to experience ecology by experimenting with your interactions with the environment
• Evaluate your own physiological and psychological adaptations and responses to severe temperatures, reduced photoperiod, and decreased energy
• Consider winter as a classroom and open your imagination and all of your senses to this incredible season

Snow and Wildlife

Adaptations to snow - in an evolutionary context, a choice between avoidance and confrontation

• Migration - Escape to more temperate climes when snow and cold renders habitat undesirable or unusable.
  • Energetic cost of traveling long distance is extremely high.
  • Food along migration route uncertain
  • Uncertainties of disease, parasites, predators, and food availability at destination
  • For many bird species there is no alternative
  • Most mammals of the north do not migrate - exceptions: caribou, bats, whales
  • Costs 10 times more energy to run a given distance than fly
• Hibernation - Avoiding the problems of food scarcity and extreme cold by entering a state of much reduced metabolic activity in which body temperature falls many degrees below normal without debilitating effects
  • Homeotherms - warm-blooded animals - normally maintain body temperature independently of surrounding temperature
    • Perfected only in a few mammal species and no birds
    • Requires animals to survive for an uncertain period on finite energy reserves
    • High energy costs of periodic arousals and rewarming - chipmunks, woodchucks
    • Black bears - highly efficient hibernators
  • Poikilotherms - cold-blooded animals--having body temperature that varies with the external environment
    • Reptiles and amphibians of the north have few other options
    • Seek out safe hiding places under decaying logs, in deep rock crevices, burrows, under moss or leaf litter, or in soft mud of pond bottoms
• Resistance - Staying and enduring the rigors of the season and resisting its stresses
  • For many species of plants and insects, complex biochemical mechanisms enhance their ability to survive freezing temperatures
  • Production of glycerol inhibits ice formation in body tissues
  • Production of special ice-nucleating proteins promotes extracellular ice formation and reduces the risk of flash-freezing with supercooling
  • For winter-active birds and mammals who do not migrate or hibernate, resistance involves coping with snow and ice cover while living from day to day.
  • High foot-surface to body-weight ratio acting like snowshoes--caribou, lynx, snowshoe hare
  • Stature and musculature to lift its feet through deep snow--moose, bison
  • Color change to reduce risk of predation - snowshoe hare, ptarmigan, ermine

Ecologically Important Aspects of Snowcover and Ice on Ponds

Snowpack, snowcover, and ice have great ecological significance for organisms that live in northern regions. Inhabitants of the north have an extensive vocabulary describing all of the nuances of snow.

Snows undergo a metamorphosis or maturation process through time after they fall. Generally, snows that fall first are light and fluffy, and low in hardness and density. They become harder and denser as the winter continues.

Snow is classified on the basis of the major physical processes involved in its metamorphosis:

• Unmetamorphosed - light, fluffy snow, many fragile snow crystal forms easily distinguishable
• Equitemperature or destructive metamorphism - deterioration of the snowflake and formation of rounded ice grains in snowpack from wind, weight, or temperature
• Temperature-gradient or constructive metamorphism - changes in the vertical structure resulting from the migration of water vapor upward within the snowpack caused by a temperature gradient between the bottom and top of snowpack and interconnecting system of pore spaces within the snowpack
• Firnification - aging process of snow caused by melt-freeze and pressure metamorphism, grains of snow grow together and bond and greatly increase the strength of the pack.

For terrestrial organisms, the four most significant aspects of snowcover related to wildlife survival are temperature, depth, density, and hardness.

• temperatures vary in a snowpack, approaching air temperature near the surface and warmest near the ground- many animals take advantage of the insulating qualitites of snow by burrowing or bedding
• depth of snow limits mobility and has advantages and disadvantages for different animals
• density reflects the compaction of snow crystals within the snowpack and increases during metamorphosis
• hardness reflects the degree of bonding between snow crystals and with density is a measure of strength in the snowpack (ability to support weight)

For aquatic plants and animals, ice acts as a lid on the aquatic ecosystem limiting the amount of nutrients, energy, and oxygen entering this world of extremely stable temperatures

• The maximum density of water is at 4 degrees Celsius (39 Degrees Fahrenheit) so both warmer and cooler water rises--bottom water never exceeds 4 degrees Celsius and upper water in contact with ice is 0 degrees Celsius
• the closeness of waterıs freezing point and its temperature of maximum density dictates that pond residents must operate within a narrow range of temperatures
• ectothermic animals (body temperature stays in equilibrium with surroundings) slow metabolism, become sluggish, conserving oxygen and energy in semihibernation or undergo biochemical changes to tolerate the cold
• semiaquatic animals must compensate for the heat loss that water siphons from a warm body by constant grooming with oily secretions (muskrats), heat shunting mechanisms to reduce heat loss from bare tails and feet ( beavers), huddling in nests, and dense fur hollow guard hairs (otters)
• times of low snow cover and extended cold when water begins to freeze all the way to the bottom are threatening

References:

• Davidson, E. C. and R. E. Lee. 1998, November. When cells freeze over: Investigating solute concentration, osmosis, and cryopreservation. The Science Teacher. NSTA.
• Halfpenny, J. C. and R. D. Ozanne. 1989. Winter Ecology: An Ecological Handbook. Johnson Books, Boulder, Colorado.
• Marchand, P. J. 1996. Life in the Cold: An Introduction to Winter Ecology. University Press of New England, Hanover, New Hampshire.
• Merritt, J. F. (Ed.). 1984. Winter Ecology of Small Mammals, Special Publication No. 10, Carnegie-Mellon University Press, Pittsburgh, Pennsylvania.
• Schimelpfenig, T. and L. Lindsey. 1991. Wilderness First Aid. National Outdoor Leadership School. NOLS Publications. Stackpole Books. Lander, Wyoming.