The Common Merganser is one of our biggest ducks, about the size of some loons. Although it’s not closely related to loons, it has evolved a similar overall structure and predatory behavior. But a merganser has a unique feature: tooth-like serrations along the edge of the bill that help the bird grasp slippery fish. Common Mergansers nest in the northern states and Canada. So do loons. But loons nest on the ground at the edge of a lake, while the mergansers nest mostly in tree cavities and rock crevices near large lakes or along rivers. Learn more at BirdNote.org.