Definition:

(noun) The process of combining two or more formerly separate bird species into a single species. If one of the former species has a much greater distribution or population, it is often considered the "nominate" species and may retain the former name – both common and scientific – while other species it is now combined with are considered subspecies. Many factors are taken into consideration when different species may be lumped, including:

• Overlaps in the geographic range, including frequency of vagrant sightings
• Ability for species to hybridize and characteristics of resulting offspring
• Common behavior shared by the species, including vocalizations
• Genetic testing and DNA analysis showing similarity between species, despite what may be superficial differences in appearance

Lumping species is never considered lightly and it can take years of discussion among leading ornithological groups before lumps are accepted. Birders may lose a life bird when a species is lumped, though they can continue to count the subspecies and may regain that lifer if the new species is later split into its former members again.

Species splits are far more common than lumps, but some notable species lumping includes:

• Audubon's warbler and myrtle warbler lumped into the yellow-rumped warbler (1973)
• Whistling swan and Bewick's swan lumped into the tundra swan (1982)
• Oregon, white-winged and slate-colored juncos lumped into the dark-eyed junco (1983)
• White wagtail and black-backed wagtail lumped into white wagtail (2005)

As genetic testing advances ornithologists' understanding of how birds are related, species that may be lumped in the future include the black-billed magpie and yellow-billed magpie, the black, brown-capped and gray-crowned rosy-finches and various types of doves, gulls and parrots.

Photo – Yellow-Billed Magpie © Linda Tanner

Pronunciation:

LUHMP