The sooty fox sparrow (Passerella (iliaca) unalaschcensis) contains the darkest-colored taxa in the genus Passerella. It is currently classified as a "subspecies group" within the fox sparrow pending wider-spread acceptance of species status. It has long been suspected to be a separate evolutionary lineage due to morphological distinctness (Swarth 1920), and this is confirmed by analysis of mtDNA sequence and haplotype data (Zink 1994, Zink & Kessen 1999, Zink & Wecks