The story below is from last January, but was new news to me for how and why loons need to be rescued from the lake.
TLDR - they molt their flight feathers in winter. If they don't fly to the ocean before the lake freezes, they become "sitting ducks" on the frozen lake as they also can't walk on land/ice due to their rear legs being so far back on their bodies.
https://www.wmur.com/article/loons-l...shire/38860845
I'm guessing most of you all already knew this though!