Genetic Evidence Supports Boreal Chickadee (Poecile hudsonicus) × Black-capped Chickadee (Poecile atricapillus) Hybridization in Atlantic Canada

Abstract

Both morphological and genetic evidence support a hybridization event between a Boreal Chickadee (Poecile hudsonicus) and a Black-capped Chickadee (Poecile atricapillus) in Atlantic Canada. Plumage of the hybrid was intermediate to both parental species, with buffy sides and a dark brown cap on the head. Mitochondrial DNA control region showed the female lineage to be from a Boreal Chickadee, while Z-linked markers showed mixed Boreal Chickadee × Black-capped Chickadee heritage, likely representing an F1 hybrid. This is the first documented case of hybridization between these species in eastern North America, and it adds to the increasing evidence supporting intrageneric avian hybridization.