Postcard from the Subnivean Zone!


Channels dug beneath the snow this winter.

What, you may be asking, is the subnivean zone. Well, it is a magical world that exists between the bottom of the snow and the top of the ground, and there’s a lot more animal action there than what you may be aware of, a secret winter realm, if you will.

(Check more cool stuff about the subnivean zone.)


So when I was taking down the snow fence this weekend, I discovered telltale signs of life in the subnivean zone out in the field, little channels dug during the winter by what I suspected were voles.


To verify, I sent the photo to one of our nation’s most noted naturalists, Dr. Philip Myers at the University of Michigan, who also happens to be a fan of the subnivean zone. Always willing to share his bounty of natural world knowledge, he offered up some nice backstory and suggested I use a photo from the Animal Diversity Web (which he was instrumental in creating), see below…


From Dr. Philip Myers:
Yup, Microtus pennsylvanicus (meadow vole) runways.  Interesting, because this is an “outbreak” species.  Most years, their numbers are fairly low, but every so often their populations jump to as many as hundreds of mice/acre.  Similar to lemmings (which are in the same group of rodents as voles), but not so dramatic or regular.  Looks like this could be one of those years.  Not necessarily — the population may have already crashed — but clearly you had lots of voles under the snow last winter.  I’ll know more when I get up to University of Michigan Biological Station to do my spring “census” in May.
Short-tailed shrews also leave runways that are revealed by snow melt, but not so wide or densely packed.  And usually not in open grassland, although it can happen.
Voles can be damaging to orchards, especially during the winter, when they run out of green stuff to eat and begin chewing tree trunks to get at the cambium layer just under the bark.  Don’t know if they attack cherries!
The beast herself (or himself), Microtus Pennsylvanicus, Meadow Vole.

Article Comments

One thought on “Postcard from the Subnivean Zone!”

  1. I had these lacy vole tracks in my strawberry patch and you know they ate nearly every plant! The only protected part of the patch was where a large stick had fallen and must have provided a barrier to the runways under the snow … I’m going to revitalize the short fencing along the edges of my patch to attempt to keep these rodents out. I’m delighted to learn that this might be a peak year …

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