Tag: Kroepfl

What is that Flash of White? by Stephanie Kroepfl

Posted on by Jim Kroepfl
Ermine
Photo by saxzim.org

What keeps astounding me is how many critters live among us that I’m obliviously unaware of. This week one evening, I was hunkered down in my office that looks onto the patio beneath the deck. A flash of white outside caught my eye, but after not seeing anything, I resumed my writing. Then it happened again—a white streak crossing the window at eye level. What the heck? It’s not like Grand Lake has laboratories that a white mouse could have escaped from to save itself from cosmetic testing. Then I made a point of watching. Unbelievably, I soon saw a creature jump onto the table and then dive into the three foot pile of kindling I’d collected for our winter fires. It was pure white and the very tip of its short tail was black. It seriously took my husband quite a while scouring the Internet to figure out that I just encountered my first ermine.

This little scrapper actually has three correct names. “Ermine” is used when it’s fur is pure white, which happens in the winter, and it’s called a “stoat” when it has reddish-brown fur on its back and white fur on its belly, which is it’s summer coat. It’s also called a short-tailed weasel. Ermine can be found in North America, Europe and Asia in the subarctic and arctic climates (when winter is just rolling in, it’s kind of daunting to face the fact that subarctic mammals thrive here). Due to the ermine’s warm coat, it doesn’t need to hibernate, which is also what made its fur a prized material for the royals’ collars and coat linings in Medieval Europe. Despite that, the number of ermine in the wild is still large and stable.

And, like it’s adorable cousin the otter, it’s a ferocious carnivore. It will feed on pretty much anything it can catch—including the voles that scamper under the snow and continue destroying our lawns all winter (gorge to your heart’s content, Whitey!). Their sleek, flexible bodies allow them to easily enter their preys’ dens and burrows. The ermine will kill the inhabitant by inflicting a bite to the back of the neck, suffocating it by crushing the connection between the brain and body. After filling its white belly, it will save the excess meat for later. Then, instead of returning to its own home, the ermine will take over the now-vacant burrow . . . and then decorate the chamber’s walls and floor with the dead animal’s skin and fur. Yes, they’re seriously the Buffalo Bill (think “Silence of the Lambs”) of the Rocky Mountains.

But this wily badass doesn’t only go after small mammals. I watched a heart-warming YouTube video of a stoat (it was summer) chasing down and killing a rabbit ten times its size. And, when it can’t manage to catch the rabbit, it resorts to hypnotizing it with a “dance” until it can deliver the killing bite. So, here’s my question: do I really want to fight off the ermine for kindling all winter, or do I just resign myself to buying firestarter?

Originally published in The Boardwalk newspaper, Grand Lake, Colorado.

Staying Cozy Under Our Ice Capped Lakes by Stephanie Kroepfl

Posted on by Jim Kroepfl

As I’ve discovered since first writing for “The Boardwalk,” whenever I begin with a seemingly simple question about nature, I end up learning more than I ever expected. This week, I was wondering how fish survive under the layer of ice on our lakes. From that, I delved into the fascinating world of fish physiology, oxygen, ice and limnology, which is the study of the biological, chemical, and physical features of lakes and other bodies of fresh water. I literally had no idea this field existed. All of these topics are co-dependent (in the good way) when it comes to finding an answer to my initial question.

First, as we all know, fish do not come to the surface to breathe air. Instead, they take in “dissolved” oxygen from the water. So, if the surface is frozen, where does their oxygen come from? Since ice is porous, it does not create an air-tight seal. Heavy gas molecules such as oxygen can penetrate the ice and dissolve into the water while other gases are pushed out. Oxygen is also created by the decomposition of organic matter on the lake’s bottom, and it’s brought in by streams, rivers and springs.

Even with those sources, the amount of oxygen does drop off when our scaled neighbors’ home is capped in ice. To cope with this, most fish slow down their metabolism, which lessens the amount of oxygen and food they require. They also reduce their activity level. Some species will move sluggishly, while others hunker down almost to the point of hibernation. For example, bluegill won’t eat all winter long, relying on fat stores they accumulated in the fall. Then, there are those wily, cold lovin’ fish that inhabit our lakes. Trout remain fairly active throughout the winter; in fact, the cooler water allows them to venture into the shallower depths they can’t tolerate in the summer. Hence, the advent of ice fishing contests.

But why don’t they become ice-encrusted fish sticks in these frozen waters? Aaaah, now we get into the fascinating ecosystem of a lake. In the summer, lakes are colder the deeper one goes. But in the winter, the exact opposite is true. Our thermally stratified lakes have a warm upper layer (epilimnion), a middle region (metalimnion) with a point called a thermocline, which is the transition where the water becomes very cool. The cold, dark, lower part of the lake is the hypolimnion. Our lakes are dimictic, meaning they turn over in the fall and spring. The fall turnover happens when the upper layer of water gets cold enough to make it so dense, it sinks below the middle and lower layers that haven’t cooled yet. This pushes up the warmer, lower water which, in essence, turns over the lake’s layers. In the winter, fish can survive in the deepest part of the lake where the water is cool, but still unfrozen.

Who’d a thunk it? I ponder about fish and become versed in limnology.

Lake Turnover Phases
Illustration by National Geographic

Originally published in The Boardwalk newspaper, Grand Lake, Colorado.