December 2022 Natural Mystery Answered
Two candidates emerged in the answers to our December Natural Mystery. Congratulations to Anna Cameron, Mike Holtz, and one anonymous tracker for sorting through the evidence and correctly identifying which charismatic, semi-aquatic mammal left these troughs in the snow.
These are beaver trails. Anna kicks us off with this analysis:
"North American Beavers made these troughs waddling through deep snow to move between their foraging areas up on the river bank and the water access at the river. I can somewhat see the large back footprints trudging up the bank. Additional evidence that this animal entered the water comes from the disturbance of the ice at the river’s edge."
Mike then offers us some reasons to favor beaver over otter as our trough-maker.
"I considered both beaver and otters. For otters though, I would expect the trough to be a little narrower, and possibly smoother as well if they were sliding down. These look wider, and appear less smooth on the sides, like maybe a beaver walking up and down the path. Plus, otters probably would have used the really good looking area for sliding all the way down towards the right side of the picture :)"
Spot on (though I’m not sure I can vouch for otters preferences in sliding hills). For comparison, here are some otter slide observations from some of our local trackers:
https://www.inaturalist.org/observations/37145378
https://www.inaturalist.org/observations/10194523
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