Aberrant Colouration in the Atlantic Puffin (<i>Fratercula arctica</i>), the Common Murre (<i>Uria aalge</i>), and the Thick-billed Murre (<i>U. lomvia</i>) from Atlantic Canada

Abstract

The colour of birds’ plumage and bare parts is an important feature in choice of mate, camouflage, thermoregulation, species recognition, and flight mechanics. Abnormalities in colouration occur in a variety of species and can have important consequences for an individual’s survival and fitness. We present 7 new cases of colouration abnormalities in 3 species of auk (Alcidae) and review previous reports to correctly assign the proper form of abnormality to specimens in museums or photographs. Of the 53 reported colouration abnormalities, we reclassified 42, progressive greying being the most common (18 or 19 cases out of 42, 43–45%), followed by brown (10/42 cases, 24%), in addition to 6 cases of melanism, 4 of dilution, 2 of partial leucism, and 1 likely somatic mutation. Properly describing the form of colour abnormality improves our understanding of the frequency, causes, and consequences of aberrant colouration.