Oosthuizen & de Bruyn: Isabelline King Penguin at Marion Island 275

• Main Author: Short Commun Catio S
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Crawford; Antarc*; Marion Island
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.690.6369; http://marineornithology.org/PDF/37_3/37_3_275-276.pdf

Isabellinism is a form of pigment dilution caused by a genetic mutation that results in a reduction in the concentration of eumelanin, the pigment responsible for black, grey and dark brown feathers in birds (Van Grouw 2006). It results in a uniform lightening of dark colouration, which appears greyish-yellow or pale brown (Everitt & Miskelly 2003, Voisin et al. 2002). This colour aberration has sometimes been used interchangeably with leucism, even though it differs from leucism, which is the total lack of eumelanin and phaeomelanin in feathers (Van Grouw 2006). An isabelline adult King Penguin Aptenodytes patagonicus was sighted at sub-Antarctic Marion Island (46°54′S, 37°45′E) on 21 November 2007 [Fig. 1(a)]. The individual was seen at the periphery of the large Kildalkey Bay King Penguin colony, where approximately 18 000 pairs of adults breed (Crawford et al. 2003). The face, dorsal surface and flippers were pale grey in contrast with