Behavior Swans gather together in flocks except during the breeding season when they pair. In general, they are bold aggressive birds, taking on animals much larger than themselves. Due to their size, swans have difficulty becoming airborne, requiring long runs over land or water to take off. They are strong fliers, but poor at maneuvering and many deaths are caused by collisions. Black swans produce a whistling sound in flight caused by the downstroke of their wings.
Swans feed by dipping their heads underwater and pulling up vegetation.
They are good swimmers but never dive. Reproduction Swans are strictly monogamous. During the courtship the male caresses the females head and neck, uttering soft and gentle cries. Both birds help in building the nest, although the female does most of the building. The males aggressively defend the nesting territory, chasing away other birds and the pair's young from the previous spring.