Loons will give a yodel or tremolo call when they feel threatened. They will also rise up out of the water, possibly row across the water too while doing a penguin dance. If you see a Loon do this and there is no other danger around, then it means YOU are too close and need to back off. These particular photos I shot from a distance as an eagle flew overhead. Eagles are a big predator of Loon chicks.
P.S. Some fantastic news, the Loons are building a nest right at the end of my dock at the log cabin. It's on a grassy tuft that is about 5 feet away from shore. I never could have dreamed that something this spectacular would happen to me! (By the way, our log cabin is named "The Loons' Nest" - ironic, eh?
Plant some milkweed
3 minutes ago