What Colour Is That Sparrow? A Case Study: Colour Aberrations In The House Sparrow Passer Domesticus

Abstract

In this paper 16 distinct, heritable colour aberrations (mutations) in the House Sparrow are described, based on specimens found in museum collections, records of individuals seen in the wild and from bird breeders keeping aberrant coloured sparrows in captivity. Based on the frequency found in the museum specimens Brown is the most common mutation in the House Sparrow, followed by Ino and Albino. Besides the mutations there is also a, presumably, non-heritable aberration called Progressive Greying described. Progressive Greying is in fact by far the most common colour aberration found in the species but was, in the past, always assigned as ‘Partial Albino’ without its real nature being understood. This paper will give some insight in the nature of Progressive Greying.