A Crappie Evening

First my car got stuck on the snow-covered lake. Then the truck got stuck. Finally, with the car sitting back at the landing on solid ground and everyone squashed into the truck, we reached the honey-hole.

Leaden skies hung low over the snow covered lake. Two other little ice fishing houses sat just off the pine-treed point as we parked the truck at the third point of the triangle. Out came the sled with the pop-up shelter.  Out came the five gallon pails filled with rods and holders, ice scoops, and minnows. The power auger growled to life, and soon we had about nine holes, six tip-downs, three people keeping watch, and three people jigging.

“The crappies start biting at about four o’clock,” said Larry, our friend and fishing guide, as he slipped the last hook under the dorsal fin of a crappie minnow.

3:58…4:00…4:02…4:04... “There’s one!” someone shouted as the pole in the rod stand tipped down. My mom quickly grabbed the pole and set the hook. Hand-over mittened hand, she pulled up the line until the brilliant scales of a black crappie slid out of the hole and onto the snow. Right on schedule.

The next fish got away, though, as a rusty angler (who will remain nameless) tried to pull it straight up out of the hole. Also known as “papermouths,” crappies have tender mouths that can’t support their own weight, and a hook will pull out easily.

After that, I kept busy watching the other tip-downs, delivering crappie minnows into waiting hands, and scooping ice from the holes as the water skimmed over. Running through deep snow in my clunky boots, I felt like a little kid again. The three holes closest to deeper water were the most successful, presumably since the hungry crappies encountered these first as they moved from the deep lake into the shallows off our point.

Black crappies prefer habitats with little or no current, clear water, and abundant cover. Schools of crappies find shelter in plants and underwater structures, such as logs, stumps, and rocks. Crappies feed some early in the morning and mostly in the evening. Smaller crappies eat plankton and small crustaceans, while larger fish eat insects, crustaceans, small fish, and minnows. Their predators include larger fish, great blue herons, snapping turtles, kingfishers, and of course, anglers.

With shimmering light-green scales densely patterned with dark spots, and rows of dark more spots on their fins, this colorful and numerous member of the sunfish family is a popular game fish. While their original range was likely confined to the eastern US and Canada, black crappies now inhabit all of the lower 48 states.

It was not even 5 o’clock when I dumped the fish bucket out on the snow to count our haul. “Seventeen…eighteen…nineteen…we just need one more to make twenty!” Freezing rain was pelting our backs, and we took turns brushing the skim of ice off each other’s jackets. The biting wind began to steal our inner warmth.

Larry started to pack up the shallowest tip-downs that were not catching anything. I took the pole from my friend when he decided to crawl into the clamshell tent with the propane heater to warm up. Up and down. Up and down. I pulled the line up just to make sure that the minnow was still alive, and tried to make sense of the red flashes on the fish finder. I think I was more focused on trying to jig correctly than on actually catching anything when my bobber bobbed. With a little yank and a yell, I set the hook and hauled up our final fish.

The faint odor of fish slime rose from our mittens as the truck heater warmed up. We bounced and jostled back onto solid ground, heading toward our dinner. In the back of the truck was a pail of beautiful fish whose dinner we had interrupted. Some days it sure is good to be part of the food chain!

Predator and Prey

Ice pellets sting my cheeks as I whizzzzz down a steep slope on my skis. This roller coaster hill at the Rock Lake ski trails zooms me all the way up to the top of the next knoll. As I glide over the crest and begin to pick up speed on the next downhill, I notice tracks in the fluffy snow on the side of the trail.

On several previous occasions, I have purposely wiped out so I could go back and look at tracks, but just a quick look at these allows me to guess their maker. Two feet, each less than an inch wide, planted side-by-side, one slightly ahead of the other, and with an impressively long leap between pairs of tracks. Must be a weasel.

We have three small weasels in Wisconsin—the least weasel (the world’s smallest carnivore!), the short-tailed weasel, and the long-tailed weasel. Males are quite a bit bigger than females in each species, so a male short-tailed weasel could be just as big as a female long-tailed weasel. I could not identify these tracks to species, but all three share some amazing characteristics.

As extremely active critters with heart rates of up to 500 beats per minute and correspondingly high metabolisms, weasels must eat about 30% of their bodyweight each day. Fortunately, they are adaptable predators. Rabbits, mice and other small rodents are favorite prey, and weasels will even follow mice into their burrows. A flexible spine allows weasels to maneuver easily in tight spaces; sensitive whiskers and a great sense of smell guide weasels in the underground darkness; and taking over the den of their prey saves them the effort of digging their own burrow. While this may seem a bit harsh, weasels are important predators that keep rodent populations in check.

Weasels are not at the top of their food chain, though, and risk becoming prey to hawks, owls, snakes, housecats, foxes and more. Luckily, protective coloration gives them an advantage in the snow. Weasels completely shed their fur and grow a new coat twice a year. As autumn days grow short, one transition begins. If temperatures are cold enough, a white coat grows in.  If the temperature is warmer, or variable, the coat may have patches of white and brown. This helps them adapt to variable weather patterns and new habitats. The lengthening days of spring trigger the growth of the transition to their brown coat.

Through all seasons, short-tailed and long-tailed weasels wear black tips on their tails. While you might think that this would stick out like a sore thumb and compromise their camouflage, it actually provides an excellent distraction for their predators. In 1982, Roger A. Powell did an ingenious study at the Brookfield Zoo and published his findings in the journal The American Naturalist. He used model weasels of various sizes with and without black-tipped tails, and real red-tailed hawks that were trained to attack them.

Powell found that “Long-tailed weasels with tail spots and least weasels with no spots were missed significantly more frequently by each hawk than the other color-size morphs.” He also recorded that “Observers occasionally noted that hawks attempted to grasp the tail of the long-tailed, tail-spot morph but were unable to hold the tail because of poor dexterity and tail thinness; or hawks appeared to check their attack and miss at the last moment as though they had been surprised by some aspect of the weasel model.”

Thus, the tail spot on the long-tailed and short-tailed weasels serves to deflect attacks away from vital organs. Deflection marks are common in insects (think about false eyes on butterfly wings or false heads on caterpillars), but no other mammals we know of use them.

Wouldn’t the least weasels, who lack tail spots year round, be at a disadvantage? Powell concluded that their small size makes it difficult for predators to see them in the first place, and with much shorter tails, the tail spot would be too close to vital organs for comfort.

Weasels’ defensive strategies do not end with deflection marks and camouflage. Erratic movements, quick direction changes, and snow tunnels also help them evade predators. Lucky for me, all I need to catch is a glimpse of one weasel’s tracks. Just that gives me something wonderful to chew on as I glide up and over the next snow-covered hill.

Weasels, sugar maples, gall flies, ticks, wolverines, moose, skiers, snowshoe hares, lynx. We all LOVE winter. During Birkie week, the Museum is creating an exhibit called "We LOVE Winter," that will highlight the fascinating winter adaptations of animals. Come visit, learn more about critters who share your love for winter, and gain a new appreciation for this challenging and delightful season. Why do YOU love winter? Send me your reason(s), your first name, and age, and they will be posted in the Museum!

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The current exhibit, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013.

Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/.

Maples in Motion

Late afternoon sun snuck out from under a cloud bank as my skis swished easily in the freshly groomed tracks. Days like this are the reason I love living in the Northwoods.

A slight breeze knocked loose days-old snow from where it had perched since the last big storm, and the white clumps fell from branches and twigs with soft plops that were more visual than auditory. The motion drew my eyes up, and I took a moment to appreciate the woods. This section of the Valhalla ski trail, off County Road C near Washburn, climbs through an even-age stand of deciduous trees.

The dark, furrowed bark of aspen graded to creamy white in the canopy. Paper birches with dying tops still presented pure white bark at eye-level. The most common trees had the smooth, brownish-gray bark of young maples, and a quick look at winter buds on the saplings told me that this forest holds both red and sugar maples.

Red maples have been a favorite of mine since my college botany class, when I appreciated the crimson color of their twigs and buds that make them easy to identify. Autumn reinforces my appreciation of red maples, as I watch their leaves flash a brilliant rainbow of green, yellow, orange and red all on the same tree.

I also admire their resilience. I have seen them in some of the harshest habitats available: from swamps to droughty soils; in bedrock crevasses and on spongy beds of decaying organic matter; on mountainsides congregating with the toughest firs; and in soggy creek bottoms tangled with alders.

Red maples are one of the most abundant and widespread tree species in eastern North America and have the widest tolerance to climatic conditions of all the North American species of maple. And they are becoming more common.

A lack of winter cold has given the green light for red maples to move north into territory where they would previously have been killed by extreme cold. Current fire suppression policies also favor red maple, which does not do well with repeated fires, but can respond vigorously after a single fire by sprouting rapidly from dormant buds on the root crown. Seedling establishment can occur from surviving trees onsite or from seeds carried easily on the wind.

While red maple is susceptible to numerous pathogens, fire, and damage by sapsuckers, one of its leaf diseases might be thwarted by climate change. A Duke University study revealed that infections of a certain fungus were less common and less severe in red maples exposed to higher-than-normal concentrations of atmospheric carbon dioxide.

I am happy that red maples seem to have a secure place in the uncertain future of our forests, but the coming changes might not be great for its cousin the sugar maple. Researchers at the University of Wisconsin-Madison predict that sugar maple will reduce in abundance in Wisconsin. Increasing winter temperatures are causing stress and escalating insect damage. Warmer springs are making the sugaring season shorter, smaller, and less predictable. Although red maple can be tapped for making syrup, its season is frustratingly short. Red maples flower much earlier than sugar maples and the sap becomes unpalatable after bud break.

Buds still clasped tightly against the cold on this February day, but I was warm from a long climb. As I reached the top of a hill and rounded a corner, the forest changed. A rosy sunset glowed through the heavy bows of balsam firs. I pushed off once with my poles to gain momentum and went whizzing through a gnarled stand of oaks. A sharp corner forced me to step out of the tracks, but I kept my balance and savored the wind in my face, soon gliding into a cathedral of pines. Glimpses of sky showed that it was still going through its full palate of pinks.

A world in motion may be confusing, and sharp turns in the path may throw us off balance. Change often means losing as well as gaining. Sometimes we might rather just stand still, and savor a particular place, and a particular moment. Though change will never end, we can help guide its direction and strive to find beauty in every shifting hue.

To Freeze or not to Freeze?

It is easy for us relate to the mammalian strategies for winter survival that I wrote about last week, but when you look at the invertebrate crowd, things start to get a little crazy. Invertebrates can use any of the methods that we discussed last week to survive the winter, but they do not have the advantage of an internal furnace to keep them warm. In order to hibernate, invertebrates must either tolerate being frozen, or avoid it.

One example of a freeze tolerant insect is the goldenrod gall fly larvae. You may remember from the fall, these are the critters that overwinter in a little round house that they prompted the stem of a goldenrod plant to form around them. Fall temperatures and shorter days trigger the accumulation of cryoprotectants (glycerol and sorbitol), which provide safe, non-destructive places for the ice crystals to form in the larva’s cells. Then when the outdoor temperature falls below 17 degrees F, the larvae freeze solid, and happily survive with as much as 65% of their body water turned to ice.

Although gall fly larvae can endure multiple freeze-thaw cycles over the winter, warmer temperatures increase their metabolism, and reduce their body size. When they hatch in the spring, the resulting adults – which do not feed – will not be able to lay as many eggs. As our winters become more variable with climate change, will we see a decrease in goldenrod galls?

In contrast, frost intolerant invertebrates go to great lengths to prevent ice crystals from forming in their bodily fluids. They use special anti-freeze chemicals that allow them to “supercool.” Supercooling is when a liquid is cooled to a temperature below its freezing point yet does not freeze. However, if the critter cools below its supercooling point, or if another disturbance promotes ice crystal formation, it will freeze solid and die.

One of the most hated creepy-crawlies in the Northwoods is frost intolerant and uses supercooling—the deer tick. In North America, larval deer ticks hatch in the late summer and fall, quest for a bloodmeal, and molt into nymphs after feeding. These newly molted nymphs must overwinter before emerging in the late spring or early summer the following year to quest for their next (nymphal) bloodmeal host. Nymphal deer ticks are the most troublesome life stage for humans, because they are often infected with Lyme disease and other similar diseases. What’s more, the nymphs are tiny, and thus difficult to detect, and they are active in the late spring through summer, when people spend the most time outside.

Currently, ticks seem to have a high rate of winter survival (85%). Snow cover helps to insulate them, so scientists predict that one effect of cold, dry winters like this one might be lower tick survival rates. In addition, wetter winters might foil their attempts at supercooling, because moisture can instigate crystal formation. Unfortunately, scientists have not found evidence that tick survival rates are decreasing due to our weird winters. It seems that ticks are just very good at finding cold, dry places in the leaf litter where they can supercool and not freeze.

Ticks are crafty, too. A study published in 2010 by Yale School of Medicine and others found that ticks infected with Anaplasma phagocytophilum (which causes the disease anaplasmosis in humans) have an enhanced ability to survive the cold. The Anaplasma helps ticks produce an antifreeze protein. The protein bonds to crystal structures to prevent them from growing. Scientifically, this is a fantastic example of a symbiotic relationship where both creatures benefit. Personally, it just seems unfair that what makes ticks more dangerous to us also makes them more numerous.

As our winters become less predictable, less like “the good old days” we remember, the strategies that various critters have devised for winter survival may become insufficient. Global climate change has been described as the greatest natural experiment in the history of science. We may not always be happy with the creatures who are able to come out of the experiment ahead, and it may not always be fair.

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The current exhibit, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013.

Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/.

How do YOU Survive the Cold?

Sub-zero snow squeaks and crunches loudly underfoot, frost gathers on all the windows, and the sharp air cuts deep into our lungs. We all deal with the bone-chilling cold of January in different ways. Some of us skedaddle to warmer climes, some of us burrow in to a pile of comfy quilts, some of us just grin and bear it, and others snap into skis and thrive.

It is no different in the natural world. Monarch butterflies, colorful warblers, and green darner dragonflies high-tail it south for the winter. They cannot tolerate the cold, not to mention freezing solid, so their strategy is cold avoidance.

Bears, raccoons, chipmunks, and skunks snuggle into burrows and go into hibernation (a long deep sleep) or torpor (a series of long naps). Their “comfy quilts” take the form of thick fur and layers of insulating fat. Their lowered metabolisms mimic those glowing coals in your woodstove, just waiting for a blast of spring air to fan the flames back to life.

The vast majority of northern animals just grin and bear it, in my opinion. Take for example my chickadee neighbors. On -17 degree mornings they fluff up their down jackets and go about their seed-eating business with a resolute cheer. I would not say they love it, though, since the early love songs I heard during the last thaw have been silenced by the frigid stillness.

The animals that truly thrive are those who have adapted so well to cold and snowy winters that it gives them an advantage over competitors. Skiers, for one, stay in shape while bikers and runners may lag. Lynx can outcompete bobcats and fishers for food by walking easily on top of deep snow.  Snowshoe hares go where mere cottontails would flounder. With long legs and thick hair, moose can exploit harsh, remote, habitats far out of the reach of shorter-legged deer.

It is easy for us relate to mammalian strategies for winter survival, but when you look at the insect crowd, things start to get a little crazy. Insects can use any of the methods mentioned above to survive the winter, but they do not have the advantage of an internal furnace to keep them warm. In order to hibernate, insects must either tolerate being frozen, or avoid it.

Next week we will take a look at how two common invertebrates survive the winter. Until then – stay warm through whichever strategy works best for you!

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The current exhibit, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013.

Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/.