Swans fly and swim well. They do not dive, but merely submerge the head and neck, sometimes also the forward part of the body, when foraging for food. By changes in their posture, these gregarious birds communicate to other members of their flock when they are about to fly. This is an important signal, for larger-bodied birds need considerable takeoff space. Thus a Black swan's flight is heralded when the bird raises its neck, smoothes its plumage and face into the wind.
Swans fly with matchless blend of elegance and power.
They have been clocked at speeds of up to 50 miles per hour. Swans will attack any human who intrudes on their nesting territory. Belligerent, ill-tempered and territorial, they will not tolerate other swans, except their mates and young. The general rule is for one pair of swans to occupy the same pond or stretch of stream for their 30 to 40 years life span. Swans frequently hiss, grunt, or when they are caring for their young cygnets, even bark like dogs.