Ray Yeager on Instagram: "Loon “Calls” … 1st Wail, 2nd Tremolo, 3rd Yodel. The wail is sometimes used to locate partners or during the presence of an eagle, the tremolo is a distress call, and the yodel is a territorial warning to intruder loons. Only the males make the yodel call. They also make gentle “hoots” between themselves."

Ask the Scientist - National Loon Center Foundation

Understanding Social Gatherings: The Basics - The Loon Project

6 strange loon behaviours, explained