The answer is ... NO ONE was CHEWING on the Alder. Those are the marks
from a CHAIN SAW!
A trail maintenance crew had been through a while before, and they
had used a chain saw rather hurriedly and sometimes sloppily. The alder
stick shown in the photos was loose in the snow, and had somehow ended
up in an upright position, making it look like, at first glance, that an
animal had been chewing on the branch.
This is a good quiz to help teach us to shake free any preconceived
notions we may have about a particular tracking situation. It reminds us
to always step back and look at things fresh. One of the most common
errors made by trackers if they are with others is that of believing
what someone says about the situation. "Looks like a ---", someone says,
and sometimes it sure is hard to break free of the idea of whatever it
is they are saying it is!