PLUMAGE ABERRATIONS IN ICTERIDAE IN BRAZIL

Plumage aberrations in Icteridae

Abstract

Plumage aberrations are uncommon phenomena in wild birds and remain poorly documented in neotropical taxa. Here, we provide the first synthesis of melanin-related plumage aberrations in Icteridae from Brazil based on published literature and online ornithological platforms and report a new case of aberrant plumage in the Giant Cowbird Molothrus oryzivorus. We compiled 32 documented records involving eight species from seven genera across nine Brazilian states, within the Atlantic Forest, Cerrado, and Pampa. Progressive greying was the most frequently assigned diagnosis (65.6%), whereas five records could not be confidently assigned to a single category. Most records came from Rio Grande do Sul and São Paulo. Because photographic diagnoses may be uncertain, records were classified only when diagnostic features were sufficiently visible, and uncertain cases were explicitly indicated. The Giant Cowbird exhibited predominantly whitish plumage but retained pigmentation in the bill and feet, ruling out complete albinism. Our results show that plumage aberrations in Brazilian Icteridae remain scarce and geographically uneven and highlight both the value and the limitations of online ornithological platforms for documenting rare phenotypes.