Saturday was the Christmas Bird Count in our area, and wouldn't you know it would be the most frigid morning we've had this whole mild December -- only about 10 F. as we set out around 8:00. One bright side was seeing some fascinating ice formations along the creek near Dennison, where we always stop in hopes of seeing birds, but rarely see any even when there is open water. This time we saw a couple of goldfinches.
Click on any of the photos below to see them larger. They were taken from quite some distance so they are not all crystal clear, but you can see what a variety of patterns and structures were to be seen.
I haven't studied ice formation much, but there is some basic background in this Britannica article.
The only ducks we saw all morning were a group of 14 mallards splashing vigorously in a small area of open water in the middle of the pond south of Superior Drive. Man, that looks cold.