"I'll Stand By You"...Reproduction

          As mentioned briefly in the habitat section, during mating season, black-necked swans separate from the flock into their mating pairs.  Black-necked swans mate for life, becoming very territorial and aggressive during nesting.  These swans, which are normally very social, become very dhttp://images.google.com/imgres?imgurl=http://farm3.static.flickr.com/2273/2162604440_e24355697c_b.jpg&imgrefurl=http://animalphotos.info/a/2008/09/15/several-black-necked-swans-swim-off-beach-in-natural-south-american-habitat/&usg=__WO4VP4ewWn9kPmI3hnoC4Goc8e8=&h=511&w=1024&sz=312&hl=en&start=3&tbnid=tVyQiyhsIaAtGM:&tbnh=75&tbnw=150&prev=/images%3Fq%3Dblack-necked%2Bswan%2B%252B%2Bhabitat%26gbv%3D2%26hl%3Den%26sa%3DGefensive and will pursue any intruder that ventures near their nest, attempting to bite or beat them with their wings.  Black-necked swans are typically very quiet birds, but during their breeding season both sexes are extremely vocal.  The male swan courts the female through a series of calls and head tilts.  During breeding season, the red knob at the base of the beak of the male swan becomes dark scarlet and enlarged.  The breeding season lasts from July to September with females laying four to six eggs at a time, up to three times a season.  The female swan, known as a pen, is the only one who can sit on the eggs, while the male (cob) protects the nest and brings her food.  After around 25 days the eggs hatch and the cygnets (baby swans) are dependent on their parents for their first year of life.  Black-necked swans are unique in that both of the parents carry their young on their back continuously for the first three weeks of life.  This bird molts (loses its flight associated feathers) once a year, males and females at different times.  The female swan becomes flightless soon after breeding, spending her time incubating the eggs.  The males molt only after the female is finished.  The swans do this at different times so that one of the parents is always ready to defend their young.

Parent swan carrying a cygnet.