Language: English with trilingual summaries in English, French, and German
Records of aberrant grebes Podicipedidae of all species worldwide (i.e. mentioned in the ornithological literature; reported by museums of natural history; retrieved via the internet; stemming from own observations) were aggregated in a register. Based on the available descriptions and photos, each record was analysed individually with respect to the cause for its abnormal appearance. The study was based on the assumption that grebes’ integument colouration is almost entirely based on the two melanin colour pigments, eumelanin and phaeomelanin. Its main objective was to distinguish between genetic and non-genetic causes of aberrations and to correctly classify individuals in the first category according to the genetic mutations.