Loons have solid bones, which makes them denser than water therefore making it easier to dive deep into the water. Loons breed in the summer and both parents spend equal time sitting on the nest incubating the two brown eggs. Their nests are on a mound by the water's edge. Both parents help raise the chicks and for the first three weeks the chicks spend most of their time riding on their parents' back. They do this to avoid hungry predators like fish and turtles.
Loons fly south in late fall and return again in late spring.
They need the wind to help lift them up out of the water. In the last few decades, scientists have found that acid rain which falls into lakes can stop loons from being able to breed. The dangerous chemicals also poison the fish, crayfish, and mollusks that the loons feed on. When these animals die the loons starve. This is more evidence that humans need to stop polluting because of the negative effects on wildlife.