I spent the first 18 years of my life in North Carolina, and I can count the number of times it snowed in my hometown (village, really) on one hand. Now that I've moved to Wisconsin, deep in the frigid North, I find myself wondering every year around November where all the little critters go in anticipation of the impending deluge of snowflakes. Birds obviously migrate South, and bears hibernate in cozy holes, but what about squirrels and rabbits?
Optional digression: Earlier this year I met two baby bunnies! There are a ton of rabbits around my apartment complex. One evening I was walking up to the front door when I noticed some movement. Being a nature enthusiast, I stopped immediately because I suspected there might be an interesting critter in the vicinity. Sure enough, two little bunlets (if that's not the term, it should be) and their mama were in the grass right in front of my building. I crouched down to try to look less threatening, and one of the little fellows hopped right up to my foot! He (or she) touched me! I have high hopes for that bunlet and his family.
Back to original story! It's entirely possible, I suppose, that other furry creatures also migrate in the harsher months, but what about snakes and frogs and insects? Surely they don't ALL migrate. So, I've been curious for several winters and I finally bothered to do some in-depth research (i.e., I googled it). Because this topic has already been covered by other intrepid bloggers, I've included a bonus look into the life of the wood frog!
Optional digression: Earlier this year I met two baby bunnies! There are a ton of rabbits around my apartment complex. One evening I was walking up to the front door when I noticed some movement. Being a nature enthusiast, I stopped immediately because I suspected there might be an interesting critter in the vicinity. Sure enough, two little bunlets (if that's not the term, it should be) and their mama were in the grass right in front of my building. I crouched down to try to look less threatening, and one of the little fellows hopped right up to my foot! He (or she) touched me! I have high hopes for that bunlet and his family.
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| HE'S SO CUTE |
Back to original story! It's entirely possible, I suppose, that other furry creatures also migrate in the harsher months, but what about snakes and frogs and insects? Surely they don't ALL migrate. So, I've been curious for several winters and I finally bothered to do some in-depth research (i.e., I googled it). Because this topic has already been covered by other intrepid bloggers, I've included a bonus look into the life of the wood frog!
It turns out that two of the animals I mentioned before, squirrels and rabbits, actually stay active in the winter and just do their best to find food and keep warm in trees and burrows [1]. Chipmunks, on the other hand, hibernate like bears [2].
Reptiles like snakes will also take shelter in burrows. Fish will move to the bottom of lakes and ponds where the water won't freeze, and turtles and frogs hide out in water bodies too, entering a dormant state and absorbing oxygen from the water through their skin [3].
Some insects, such as the silkworm Bombyx mori, will enter a hibernation-like state called diapause during the winter [4]. Others lay eggs which will hatch in the spring, then die. Still others simply hang out in various hidey-holes (tree bark, fallen logs, dirt). An interesting variation on this theme is the gall. You've probably seen plants that seemed to have warts, like so:
This is actually a wee insect's home. Bugs like eriophyid mites secrete compounds that bulge out the plant tissues, then live there and munch on the plant throughout the winter like a bunch of degenerates [5].
And then there's the wood frog. Rana sylvatica, much like Geobacter sulfurreducens (I have a blog post on that, too!), just doesn't give a fuck.
These frogs can survive being frozen in the winter, so when it starts to get nippy they just hunker down under some dead leaves near a woodland pool (gotta be ready to start making babies in the spring) and turn into frog cubes.
They are able to do this because they accumulate cryoprotectants--antifreeze*, basically--in their blood and tissues to decrease the formation of ice crystals that would rip their cells open. Soooper cool (that was a pun).
I'll leave you with this video of scientists playing with frozen wood frogs because...science?
*Not technically true. Antifreeze prevents freezing, while these compounds minimize the size of ice crystals that form, which reduces the stress on the cells (less stabby stabby = good). They do also prevent freezing to some extent because of freezing point depression, but that does not seem to be their main purpose. There ARE critters that have antifreeze in their blood (some Antarctic fishes come to mind), but those are a topic for another day :)
References:
Some insects, such as the silkworm Bombyx mori, will enter a hibernation-like state called diapause during the winter [4]. Others lay eggs which will hatch in the spring, then die. Still others simply hang out in various hidey-holes (tree bark, fallen logs, dirt). An interesting variation on this theme is the gall. You've probably seen plants that seemed to have warts, like so:
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| Ewwwwwwww |
This is actually a wee insect's home. Bugs like eriophyid mites secrete compounds that bulge out the plant tissues, then live there and munch on the plant throughout the winter like a bunch of degenerates [5].
And then there's the wood frog. Rana sylvatica, much like Geobacter sulfurreducens (I have a blog post on that, too!), just doesn't give a fuck.
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| Pretty cool background, huh? Even if it's not as cool as Arya. I got it here. |
These frogs can survive being frozen in the winter, so when it starts to get nippy they just hunker down under some dead leaves near a woodland pool (gotta be ready to start making babies in the spring) and turn into frog cubes.
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| Like this. Except, you know, frog. |
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| Yeeeeeaaaahhhhh. |
They are able to do this because they accumulate cryoprotectants--antifreeze*, basically--in their blood and tissues to decrease the formation of ice crystals that would rip their cells open. Soooper cool (that was a pun).
I'll leave you with this video of scientists playing with frozen wood frogs because...science?
*Not technically true. Antifreeze prevents freezing, while these compounds minimize the size of ice crystals that form, which reduces the stress on the cells (less stabby stabby = good). They do also prevent freezing to some extent because of freezing point depression, but that does not seem to be their main purpose. There ARE critters that have antifreeze in their blood (some Antarctic fishes come to mind), but those are a topic for another day :)
References:
- http://wdfw.wa.gov/living/rabbits.html
- http://animals.nationalgeographic.com/animals/mammals/chipmunk/
- http://www.newton.dep.anl.gov/natbltn/400-499/nb485.htm
- Okitsugu Yamashita (1996). Diapause hormone of the silkworm, Bombyx mori: Structure, gene expression and function. Journal of Insect Physiology 42(7):669-679.
- Robert Wawrzynski, Jeffrey Hahn, and Mark Ascerno (2005). Insect and mite galls. University of Minnesota. http://www.extension.umn.edu/garden/insects/find/insect-and-mite-galls/
