I suppose it just could be coincidence. Last year, our only sighting of Mute Swans in the heart of the lake (near Big Island) came the day before the lake froze over.
Sure enough, yesterday--a cold and crisp winter's day--we saw them again in the same location. Today we have Lake Manitou with a new top of winter ice.
This is tricky for us because we have a "do not miss" appointment tomorrow. Will the ice hold us?