Novel hybrid finds a peri-urban niche: Allen’s Hummingbirds in southern California

Species range expansions and contractions can have ecological and genetic consequences, and thus are important areas of study for conservation. Hybridization and introgression are not uncommon in closely related populations that experience secondary contact during a range expansion. Allen’s Hummingbird (Selasphorus sasin) in California comprises two subspecies: the migratory S. s. sasin, which winters in central Mexico and breeds in central and northern California, and the resident S. s. sedentarius, which lives and breeds year-round on several of the Channel Islands off the California coast. Within recent decades, Allen’s Hummingbirds have been found living and breeding year-round in the southern California peri-urban mainland near Los Angeles. Ornithologists assumed that the L.A. birds were an expansion of the island subspecies, S. s. sedentarius due to similar but very subtle morphological characteristics. However, the genetic relationships among the three putative populations of All...