When a loon is several years old, his readiness for mating shows in fancy, striped and patterned plumage. He sets up a territory on the edge of a lake and attracts a female by making yodeling sounds. Once a female responds, the male and female court each other by mewing softly and singing duets. If all goes well, they become a mated pair. The mated pair builds a nest of aquatic plants and mud on the water's edge. They defend their territory from other loons using a variety of aggressive calls (including toots, wails, and tremolos). The female typically lays two eggs, and both parents incubate them, taking turns. The chicks that hatch after about a month ride safely on their parents' backs around the lake. Until they mature, they peep and yelp for food and are rewarded with small fish, insects, and crayfish that the parents catch.