In 2016, due to research showing that the only distinguishing characteristic between American and Caribbean coots, the presence or absence of red in the frontal shield, was not distinct to Caribbean coots as some American coots, in locations where vagrancy from Caribbean populations was highly unlikely, had fully white shields and, therefore, there was no way to reliably distinguish the species, and there was no evidence of Caribbean and American coots engaging in assortative mating, the American Ornithological Society lumped the Caribbean coot as a regional variation of the American coot. The American coot is a highly gregarious species, particularly in the winter, when its flocks can number in the thousands. When swimming on the water surface, American coots exhibit a variety of interesting collective formations, including single-file lines, high density synchronized swimming and rotational dynamics, broad arcing formations, and sequential take-off dynamics. The American coot can dive for food but can also forage and scavenge on land. Their principal source of food is aquatic vegetation, especially algae. Yet they are omnivorous, also eating arthropods, fish, and other aquatic animals. During breeding season, coots are more likely to eat aquatic insects and mollusks—which constitute the majority of a chick's diet. The coot mating season occurs during May and June. Coot mate pairings are monogamous throughout their life, given they have a suitable territory. A typical reproductive cycle involves multiple stages: pairing, nesting, copulation, egg deposition, incubation, and hatching. The American coot typically has long courtship periods. This courtship period is characterized by billing, bowing, and nibbling. Males generally initiate billing, which is the touching of bills between individuals. As the pair bond becomes more evident, both males and females will initiate billing only with each other and not other males or females. After a pair bond is cemented, the mating pair looks for a territory to build a nest in. A pair bond becomes permanent when a nesting territory is secured. Copulation behavior among coot pairs always falls under the same general pattern. First the male chases the female. Then, the female moves to the display platform and squats with her head under the water. The male then mounts the female, using his claws and wings to balance on the female's back while the she brings her head above the water. Sexual intercourse usually takes no longer than two seconds. The American coot is a prolific builder and will create multiple structures during a single breeding season.