Check out the fuzziest additions to the Fort Worth Zoo. Two black-necked swan cygnets hatched in February 2015 and can be spotted catching a ride on their parents' backs in Waterfowl Walk. The cygnets' light gray plumage will turn white by the time they are 2 years old and they will develop distinctive black feathers on their necks and a bright red knob on the top of their bills. As the fastest of all swan species, the black-necked swan can fly at speeds of up to 50 mph once fully grown.