White black swan (1309/2613)

Cygnus-atratus_10870.jpg Black swanThumbnailsWhite black swan

An unusual white black swan. There are many causes of anomalous white colouration in birds which are difficult at best to diagnose from a distance. This swan may have progressive greying or be partially leucistic –two conditions that are particularly difficult to distinguish in the field. Leucism occurs when a bird produces melanin (unlike albinos) but the pigment is not correctly deposited in some or all feathers and is less common than progressive greying.

Scientific name
Cygnus atratus
Common names
black swan, kakianau
Lake Taupo, Waikato, New Zealand
Photo ID