Out in the field I found a trail showing a body print that ended with an animal diving under the snow and coming up again a metre or two beyond leaving a perfect round tunnel about 4 inches in diameter. (Sorry, I don't really think in metric when it comes to small linear measures, I just pretend sometimes. I really do think in celsius when I think about temperature, and kilometres when I think of driving distances.)
This diving under the snow is a weasel trait. The holes this creature left looked too big for weasel to me. So I consulted the books. None of my tracking books talk much about the kind of sign this mode of travel leaves--they talk more about the experience of seeing a weasel bounding across the snow and disappearing, only to reappear several feet on.
There was a suggestion though that a long-tailed weasel (or ermine) might leave this big a hole. On the other hand, the size fits a marten or a mink better. Fishers don't generally snow dive this way--and I think would leave bigger sign than this. Argument for weasel: habitat. One would be more likely to find a weasel in a fence line or under a shed than either of the other two. Mink generally hang around and in water. Martens are more inclined to forest. But any of them might be moving around in winter. I've found otter sign (tracks and slides) in the cedar bush in winters past, and that's pretty far from suitable otter habitat.
The tracks, trails, tunnels, lead from under the shed out into the field and into an old groundhog burrow in an old mound left by a topsoil harvest of several years ago. I fear our latest yard rabbit may have been eaten by this visitor last night (not that I found remains, just that the yard rabbit has in the past hid out under the shed, and there was no rabbit visitor to the bird feeders last night). But even so, there may be enough rabbits and nice places to hole up to keep this creature around for a while--so maybe, just maybe, I'll get to see it. If it's white, it's a weasel. If it's very dark, it's a mink. If it's a little lighter, and cuter, it's a marten. So if I do get to see it, I think I'll be able to identify it. But even if I never do--what a pleasure it is to see strange new spoor out there.