An opportunistic feeder, the American coot feeds mainly on plant material, but will also eat insects, snails, tadpoles, and small fish (2). While breeding, it gorges on seasonally abundant water insects, and the chicks are fed almost exclusively on this arthropod prey, until they gradually switch to a more vegetarian diet (8). This adaptable bird will also walk considerable distances to graze on terrestrial grasses and even scavenge for dead birds (3). On water, it may upend to feed upon submerged vegetation or dive in shallow water before bringing its food back up to the surface to consume it (2) (3).
Although gregarious for much of the year, during the breeding season, which runs from April to July in North America, the American coot separates into monogamous pairs which fiercely defend territories from other coots (2). Renowned for the aggressiveness with which it repels intruders, the male American coot marks its territory by patrolling, charging and water splashing, but on occasions fighting ensues, and it will viciously attack trespassers by striking with the bill and slashing with the claws. Shortly after arriving at breeding sites, the bond between breeding partners is reinforced by courtship displays involving bill touching, head bowing and preening (3). A floating nest made of piles of vegetation anchored to a bank is then constructed by both birds, usually within a few metres of open water. A clutch of 6 to 15 eggs is subsequently laid and incubated for 22 to 27 days. Capable of swimming almost immediately after hatching, the chicks soon leave the nest, but regularly return to the platform to be brooded and fed by the parent birds, before eventually becoming fully independent three to ten weeks later (2).