Several CLLS volunteers have commented in letters or survey reports about seeing large flocks of loons on their lakes. There are at least three possible explanations for the large numbers of loons observed on some lakes. I have seen these gatherings as early as July. Some researchers suspect that social gatherings later in the summer let loons slowly prepare for the presence of other loons during migration and on the wintering grounds. These non-breeding loons will often group together.
Loons also group together just before migrating, a behaviour known as staging.
Staging tends to happen on lakes with good fish stocks in September or October. The more I observe loons, the more I realize that, like humans, each is an individual. Therefore, there are probably as many reasons for groups of loons as there are groups of loons.