The Common Loon doesn’t nest on Kootenay Lake. The spring freshet would flood the nests it must make on the edge of the shore. Rather, loons nest on little mountain lakes high above Kootenay Lake. During this nesting time, the bird is territorial and will drive off competitors.
However, when the breeding season is over and they prepare for their migration to the Pacific Coast, loons are social. They gather in (what are called) rafts on those larger lakes that have abundant fish. Kootenay Lake serves them well as they prepare for migration. We can hope to see rafts of loons here for the next month.
A raft of loons swims by as it hunts for fish.