It was a rainy nest swap at 7:10 this morning. Dad had done the night shift, which is a little out of the ordinary for this pair but nothing to worry about.
On average, female loons tend to do more of the night-time incubating. This might be due to an advantage of having the larger loon on patrol during the night or, in this case, it might be because older female loons are less tolerant of the biting insects out during daylight hours.
There doesn’t appear to be any universal nest swap schedule for loons. Some pairs seem to swap every three to five hours while others, such as this pair, prefer to do much longer shifts.