Leucism in a family group and a review of color aberrations in Burrowing Owls (Athene cunicularia)

Avian color aberrations capture public interest and sometimes indicate ecological problems. Diagnosing color aberration type can be difficult because nomenclature is inconsistent, appearance of color aberrations vary, typical coloration varies, and there are many undocumented color aberration types. One type of recognized avian color aberration is leucism. Leucism is often colloquially used to refer to all birds that are paler than normal but not albino, but it specifically refers to a plumage aberration in which, from hatching onward, birds are either all white or have patches of bilaterally symmetrical white feathers mixed with normally colored feathers, while retaining black pupils. Here, we document a case of leucism in a family of North American Burrowing Owls (Athene cunicularia). We observed a family group (two adults and five juveniles) of five leucistic, nearly all white owls, and two typically colored owls, in the Conata Basin, South Dakota, USA, in summer 2024. We also compiled all searchable records of color aberrations in Burrowing Owls across their North and South American range. We found 60 records of color aberrations, seven of which were cases of potential leucism. Twenty-five color aberrations were an unknown type in which only eye color was affected, all of them in Florida (USA) or south/central Brazil. Documenting color aberrations in birds can help expand our understanding of the types, causes, and consequences of color aberrations as well as the pigments and genetics that underly normal coloration.