Monday, February 02, 2009

Track of the Week 18

Setting: Mid January 2009 in the Snoqualmie valley. There was great tracking in the silt deposited by the flood.

1. What species? (At least three if you look close)
These are some of the nicest weasel (Mustela sp.) tracks I have seen in person. Because of the size I think they are short-tailed (M. erminea) rather than long-tailed (M. frenata) which also occur in our region. I'm not sure if there are morphological features that distinguish the species. From what I have heard it can be difficult to distinguish them even with specimens in the lab (without the use of DNA).

To me, weasel tracks sometimes look like tiny dog tracks, other times like rat tracks. In this case, if you look closely though you can see five toes showing (clearer on the right side). Often, as is the case here, I don't see much in the way of heel pads showing up.

The smaller trail going across the picture is vole (Microtus sp.) Same sub-family as the muskrat last week. Note the thin finger like toes, also that it is moving in a trot which is a common gait for this group of rodents and unusual for other common rodents in this area.

In the lower right corner there is one track that appears to be the hind track of a smaller rodent, perhaps a deer mouse.

Also there are at least two trails left by invertebrates, perhaps earth worms.

2. What gaits?

The weasel is moving in a 2x2 lope and the vole is moving in a straddle trot (a trot with the hind feet falling outside of the front).

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