The taxonomic history of Black-shouldered Peafowl; with Darwin's help downgraded from species to variation

Summary. In the 19th century the black-shouldered variety of Indian Peafowl Pavo cristatus was erroneously viewed by many as a separate species, named P. nigripennis. Others had doubts about its taxonomic status, but Darwin presented firm evidence for it being a variety under domestication, which treatment is now well established and accepted. It being a colour variation rather than a wild species was important for Darwin to prove, as otherwise it could undermine his theory of slow modification by natural selection in the wild. ‘I cannot consider it a domesticated variety, because the differences in both sexes appear to be constant, and to descend to the progeny’ (Sclater 1860: 222). ‘The black-shouldered peacock is a variety, the case is the most remarkable ever recorded of the abrupt appearance of a new form, which so closely resembles a true species that it has deceived one of the most experienced of living ornithologists’ (Darwin 1868: 292).