Making it to Spring by Dave Heithaus was originally published in the BFEC Newsletter, Vol. 18/No. 2, Spring 2014.
It may be the spring issue but based on what we all went through this winter (perhaps we are still going through at time of publication), it seemed appropriate to address how some of our outdoorsy neighbors managed those charming arctic vortices. Not the people down the block with the Subaru; they were fine.
How do Ohio’s critters survive the harsh snowscape while we sit inside sipping things from coconuts in our underwear and spinning the thermostat knob like a roulette wheel?
There are several basic ways in which organisms can make adjustments to a wintery environment: migrating, shifting behavioral patterns, bulking up, sleeping it off or a sampler platter of several options.
Migrating, as evidenced by human population densities in Southern Florida, is debatably the most pleasant, but it is also limited to a fairly exclusive group of creatures with wings or frequent flyer miles.
As the days shorten and seasonal cues compound, many of Ohio’s bird species fly to the nutrient-rich south. Some fly for thousands of miles. They are joined for some distance by Indiana and little brown bats. Lacking the fortitude of the feathered, these furry flyers generally don’t make it much further south than Kentucky. Once there, they embark on a cave-themed slumber party for the balance of winter.
As the cardinal shivering at your feeder can attest, simply having wings does not necessarily buy you a trip south. Instead, many creatures knuckle down and tough it out. Some mammals and birds front load the calories in the fall and then shift their diets for winter availability. Birds that prefer insects during the green times shift to nuts and fall berries. Mammals like foxes contract broad summer diets and focus strictly on mice and other small rodents.
Speaking of rodents, some mice and voles actually rely on a cover of snow by exploiting the subnivean zone. Which sounds too awesome to be a real thing but I promise that it is. The subnivean zone is the insulated are beneath the snow pack. Here, rodents can avoid predators while remaining somewhat buffered from the elements. Temperature sensors placed in the subnivean zone remain warmer and more consistent than ones placed in a simple, unoccupied shelter. Add heat from the rodents’ respiration and the subnivean zone is, if not cozy, perfectly acceptable for travel.
Generally speaking, animals try to reduce the amount of time they are active during the winter. Taking refuge in burrows, tree cavities or under rocks and logs can greatly reduce the amount of energy required to maintain a functioning body. Any creature with a social bone will huddle together in a group whenever possible.
For some creatures, the thought of a long, cold winter is enough to drive them to bed all together. The groundhog, a "true" hibernator, is at the vanguard of the drowsy charge. They will often construct a specialized winter burrow and remain in an inactive state for at least three months. During this time their heart rate slows dramatically, their body temperature draws down, and they slowly consume fat stored from your garden for winter slumber.
Other mid-sized mammals like raccoons, opossums and skunks will enter a temporary hibernation during particularly cold periods but none of them sleep it off like the whistle-pig!
So what about our less attractive animals? Can’t they simply freeze to death? Of course not, you monster. As cold-blooded creatures, fish, amphibians, and reptiles are greatly limited by winter temperatures but they do find ways to survive. As the weather cools and their body processes slow to a crawl, they take shelter wherever they can find it. Once there, they enter a dormant state similar to hibernation until warm spring air coaxes their blood back to flowing.
So where do they find shelter? A good hollow log or mulch pile often does the trick for a snake or lizard. Some snakes even gather together in large communal masses. How’s that for your nightmares? Many turtles, frogs, and fish take refuge at the bottom of ponds and lakes. Some burrow into the soft sediment for extra protection. With their slowed body processes and cold water’s ability to hold more oxygen, turtles, and frogs are able to breath by absorbing it through their skin. And before any sportsmen point it out: yes, there are a number of fish that remain active and delicious under the ice.
There is one creature that is not content to burrow, gather together or hide... As the wind begins to howl and sleet pounds the earth, the wood frog thumbs its nose at old man winter and (with a sneer I expect) simply freezes solid.
Thanks to some crafty physiology, the wood frog is able to create cryoprotectant chemicals (awesome) that bugger their tissues from the end-of-life damage that freezing and thawing would normally inflict. Yes, the wood frog has super-hero powers.
For some, the winter isn’t so bad because, hey, no bugs, right? Well that’s kind of a lousy attitude to take towards the circle of life so now I’m going to tell you what they’re up to while you’re gloating by the fireplace. Some of them are so saddened by human indifference that they simply lay their eggs in the fall and die. Happy now? Others spend their winters as larvae, waiting patiently underground for spring at which point they will emerge, take adult form and punish your fruits and vegetables. Still others do what everybody else seems to, find a hold, log or other such place to crawl and wait it out. And just so you know, there are actually several insects that share your precious space over winter: winter craneflies and stoneflies to name a couple. Monarchs migrate, if you didn’t know.
Spring is just around the corner. With longer days and warmer skies, we can all look forward to thawing and crawling back outside... except for any insects that laid eggs and died in the fall. They’re pretty much done with winter. As are we all.