6 strange loon behaviours, explained

In the spring breeding season, some loons will perform a “circle dance” when they encounter other loons. The loons circle each other, alternating between dipping their heads underwater and staring at each other suspiciously. Often, this behaviour happens when a non-breeding male enters a breeding pair’s territory. Sometimes the intruder backs off and leaves; other times, the dance turns into a fight. (Male and female loons also have mating rituals and interactions, but these end in…well, it’s not a fight.)

Nature doesn’t often play nice. Loons hold huge breeding territories; sometimes a breeding pair will dominate an entire lake, or, for example, a bay in a large lake. And they’ll defend it to the death from pretty much any species, including other adult loons. Other birds—some songbirds, for example—are more tolerant of each other, and will nest close together.

They’re not. At least, they’re not for the same reasons that we do. But sometimes, you might see several young loons—up to 15—swimming quietly next to each other, or in a long line. There’s no diving, no flapping, no eating, and the loons will typically stay about a body-length apart from each other. Experts believe this kind of social gathering could be a way for young loons to check out potential future mates. Oh, kind of like speed dating?

In late summer and early fall, you might spot loons clustered in a group. By this time of the year, breeding is over, the babies are born, and loons no longer hate each other. Aww, that’s nice—they’re finally getting along! But really: biologist think this behaviour (called “rafting”) helps loons feed more efficiently, and that it helps protect them from predators. Safety in numbers, and so on. Loons also gather in large groups—up to 250 birds—on their wintering grounds. Since it’s not breeding season, there’s no reason not to get along.

Have you ever seen a loon literally shaking a leg? “Foot waggling”—when a loon lifts one leg out of the water and shakes it—is still misunderstood. The loon could be trying to regulate its temperature (other birds stand, and even sleep, on one leg to do this). Or the loon could be stretching. Or the loon could be waving at you—it doesn’t have any hands. Okay, probably not that last one.

Wait, what? Who would eat pebbles? Loons don’t actually eat them—but they do swallow them. It helps with digestion. Tiny pebbles crush up the bones or exoskeletons of the prey that loons swallow whole: largely fish, but also small amphibians and crustaceans. Other birds do this too.