The Pacific black duck usually places its nest in a tree hole, but it may also use an abandoned nest from a corvid or even a nest on the ground. The Pacific black duck is primarily a vegetarian, consuming seeds of aquatic plants. It supplements its diet with small crustaceans, molluscs, and aquatic insects. The bird obtains its food through 'dabbling', submerging its head and neck underwater and tips up, raising its rear end out of the water. Sometimes, it seeks food on land in damp, grassy areas.