Tuesday, March 25, 2008

What are these dirt snake things, anyway?

Now that the snow has mostly melted, we get to look at what it has left behind. Fortunately for me, my house is off the main road and I don't have a dog, so some of the things that can make mud season so icky aren't part of my landscape.

Instead, I've got things like this:



These are ridges of loose dirt, about 5 cm wide and a few cm tall. They are just downhill from my driveway, on a 15 degree slope, but there are also some on the flatter slope of the nearby drainage. They lie across last year's grass, and across some cobbles near the side of the driveway. I've seen similar features above treeline, soon after the snow has melted, and had lots of discussions about what they are. (Critter burrows? Remnants of running water, like teeny eskers?)

Anybody know of literature on things like these? What are they?

9 comments:

Mel said...

They are from a vole. It digs around under the snow like that. We have them up here in the N. Rockies too.

Silver Fox said...

I've always assumed they were moles - I just read, though, that there are several species of voles in CA. Here's an interesting article.

Ron Schott said...

Bio-Eskers!

BrianR said...

It's like an inverted trace ... instead of a mark in the dirt, the dirt makes the mark!

ReBecca said...

I agree with Mel, rodent related. I have seen them from TX all the way to MT (although probably different critters).

Silver Fox said...

Try this: google "vole under snow" or "mole under snow" - quite a number of articles pop up!

Kim said...

I had always thought that they were some kind of trail or burrow, until I did field work with a couple guys who thought that might not be true.

I'm surprised I didn't see these in Vermont. (I had a better sense of the variety of small animals in the area there, because my cat sampled them and brought them into the house. The live bats were particularly entertaining. The flying squirrels were cute. The pheasant, full-grown rabbit, and snake were astounding. But she's gotten old, and sleeps a lot now, and she doesn't hunt very much.) Anyway, there were a lot of voles in Vermont. On the Seward Peninsula, too, I think, though it's possible that those chubby little mammals were lemmings.

Why's there so much dirt in trails? It can't be from the ground directly below, because it goes right over rocks and grass. (I should look at the grass to see if it's been chewed on.) Do the burrows fill with dirt as the snow melts?

Also: as trace fossils, they have very low preservation potential. These ones have already been stomped by the four-year-old.

coconino said...

I always assumed they were gophers, but perhaps I have gopher and vole/mole signs mixed. I believe one makes holes/mounds, where the other makes the mini bio-eskers. The unsold house across the street from me has many in the yard.

K said...

Try looking up "pocket gophers"...they are a big mover of sediment downslope by excavating during the winter and placing the material up in the snow pack..then as it melts, that material is acted on by gravity and moves down hill..

Ok - I looked it up for you :)
Pocket Gophers!.