Frozen—the Caterpillar Version

This is a woolly bear caterpillar from my part of the country.

This is a woolly bear caterpillar from my part of the country.

A year ago, I wrote an article about frogs that have adapted to survive being frozen. Turns out these frogs are not the only creatures that have developed ways to survive extreme cold. One of my favorite cold tolerant species is the Gynaephora groenlandica (no, I can’t pronounce it either!). It’s also known as the Arctic woolly bear moth. Now I realize that most of us don’t have these creatures in our backyards, but their ability to survive harsh winters make them a fun topic to explore with kids this time of year.

Arctic woolly bear moths spend the majority of their lives in caterpillar form—fuzzy, golden-and-orange little guys about 2 inches long. In order to pupate (form a cocoon), they must reach a certain body mass. However, the short Arctic summers don’t allow them to eat enough in one season to reach this magic number.

The caterpillars solve this problem by overwintering in their larval form. Specific adaptations in their bodies, including the ability to produce antifreeze compounds in their cells, allow them to survive temperatures down to -90 degrees F. Each summer they emerge for to eat and eat and eat before spinning a hibernaculum (silk “sleeping bag”) that will house them until the following summer.

Artic woolly bear caterpillars actually spend the majority of their lives frozen! After around seven summers (and up to 14!), they build up enough food resources to pupate into an adult moth. The adult moths have a few frantic days to mate and produce the next wave of super trooper caterpillars. Then the whole cycle starts all over again!

  • Frozen Planet from Discovery had a segment on the Arctic Woolly Bear Caterpillars. You’ll find it here.
  • My article on Antifreeze Animals (wood frogs) appeared last year on the KIDS DISCOVER Teacher’s Blog. It includes a classroom activity that examines one mechanism (cryoprotectants) that these animals use to survive being frozen.
  • A woolly bear caterpillar craft from Samantha at Stir the Wonder–you can change the colors to match the Arctic woolly bear.

Creature Focus–Hummingbirds

Annas hummer for resource sheetsTeachers/Homeschool Families—hummingbird feeders are an inexpensive, low-maintenance way to invite wildlife to your schoolyard, as well as your backyard. For student/teacher handouts, please see the end of the article.

On frigid fall and winter mornings my backyard fills with a most unlikely sound—SQUEAKA! SQUEAKA! SQUEAKA! The caps are intentional because if there is such a thing as a bird yelling, this is it! The voice belongs to an Anna’s Hummingbird, demanding that I thaw out the hummer feeder so he can catch a morning snack.

The presence of these tiny birds sparked my interest in birding back in 2007. Hummingbirds are summer jewels, or so I thought, who fly off to warmer climes during winter. I learned this is not the case with Anna’s Hummingbirds. Their range now extends all the way up into southwestern British Columbia and they are perfectly happy to hang around the entire winter.

In the early part of the 20th century, Anna’s Hummingbirds hung out in Southern California and Northern Baja. Non-native flowering trees planted by gardeners gradually lured the birds north. The fact that they don’t head back to the homeland during winter is due to two other adaptations. First, Anna’s Hummingbirds aren’t strict nectarivores. They also feed on tiny insects, which are active all winter on our side of the Cascade Mountains, except during periods of extreme cold.

In addition, Anna’s Hummingbirds are able to enter a state called torpor, which is similar to hibernation except that the duration is much shorter. Their breathing and heart rate slow. Their normally toasty body temperature (around 107 degrees F) falls as low as 48 degrees F. When the temperature warms, they can become active again in a few minutes. (Want to know more about torpor vs. hibernation? Click here.)

This explains the yelling. Most likely, my backyard visitor has just emerged from a cold, sleepy night and needs some breakfast to recharge his little batteries. Does he need to hang out at my feeder? That’s a trickier question. In general, birds don’t choose their wintering location solely based on human-provided food sources. You aren’t going to mess up a migration pattern just because you provide backyard feeders in the fall or spring.

That said, our West Coast hummingbirds do become accustomed to food being available at specific places, and the presence of feeders during cold snaps may increase the likelihood that “your” little friends will survive until the next thaw. If you’ve been feeding, keep it up, especially during cold snaps. Seattle Audubon Society has ideas for keeping feeders thawed here.

For Teachers
Teacher Resource Sheet–Hummingbirds

For Students
Creature Focus–Hummingbirds

Book Recommendation: In November, by Cynthia Rylant

book cover in novemberThe first frigid weather of the season is advancing upon us this week. That makes it the perfect time to snuggle with the kids on the couch and read this book. (Or just curl up yourself, with the book in one hand and hot tea in the other!)

In November, by Cynthia Rylant, is one of those books I read again and again just to experience the author’s use of words. I like all words—funny, silly, even a little gross. But, what I love the very most is when words fall together in perfectly chosen order. Sentences that make you say, “I wish I had written that”—not out of jealousy, but admiration.

The words in this book are strung like a strand of perfect pearls. I can close my eyes and see exactly what she describes. I don’t even think I need pictures—until I look at the illustrations by Jill Kastner. The soft, impressionist-style oil paintings are a just-right companion for the text.

So, before the first “Polar Vortex” of the season hits, look for this book at your local bookstore or library. I’ll leave you with my favorite line:

In November, at winter’s gate, the stars are brittle. The sun is a sometime friend.

Have a Rotten Day! Fun with Decomposition

rotten pumpkinsHave a few pumpkins left over after Halloween? Put them to good use. They are perfect vehicles for exploring decomposition in all its gooey glory. Simply place the pumpkins on the ground somewhere in your garden or schoolyard. Observe regularly–this can be informal or you can have students record their observations.

Have your students observe mold through hand-held magnifying glasses.

Have your students observe mold through hand-held magnifying glasses. (Please don’t sniff the mold!)

Pair this activity with Rotten Pumpkin: A Rotten Tale in 15 Voices, by David M. Schwartz. Rotten Pumpkin follows Jack from Halloween night splendor through his gifts to nibbling mice and slugs, rotting molds, hungry sow bugs and worms, all the way to the next pumpkin generation.

My name is Marie, and I approved this book.

My name is Marie, and I approved this book.