Black or white, color aberrations in rufous-collared sparrow Zonotrichia capensis

We present a review of the color aberrations in rufous-collared sparrow (Zonotrichia capensis), categorizing 86 individuals to pre-defined kinds of melanin expression and documenting the known range of plumage variation in this widespread species. Additionally, we monitored aberrantly colored birds in Ecuador, including two fully whitish individuals and a family where both the parents and the offspring were melanistic. The whitish birds are notable for surviving a considerable time with this condition, and the melanistic offspring evidence heritability of this phenotype. Of the 86 individuals we categorized, 29 individuals are documented in the literature and another 51 are documented on online citizen science databases (eBird, iNaturalist, and WikiAves), covering the species’ entire broad distribution. We re-identified and identified the plumage aberrations, and found individuals representative of seven phenotypes (Leucism, Progressive Greying, Albinism, Brown, Ino, Dilution, and Melanism). Progressive Greying was the most common condition encountered, with 50 reported cases. Ecuador was the country with the most records of aberrant birds, totaling 27 individuals. Our results highlight the utility of a standardized vocabulary for plumage aberrations for characterizing the range of phenotypes exhibited by a common passerine species, and serve as motivation for the continued formal publication of these records which have relevant implications, as we briefly discuss.