There are three principal methods humans use to evoke avian vocalizations. This paper explores the two that are constrained by human language: onomatopoeia and warblish. In onomatopoeia, new words are created to mimic sounds within the constraints of a language's phonology. Warblish, named and thoroughly described for the first time in this paper, is the imitation of avian vocalizations using existing words in human language. None of the conventionalized ways humans imitate birdsong has yet been studied rigorously, least of all warblish, for which a term has not even existed. Combing the ethno-ornithological literature for instances of warblish shows patterns in its functions and semantics across cultures, which range from friendly messages to ribald mocking. Warblish may evoke perceived ties between bird calls and other natural phenomena and can even offer clues to historical contact between human communities. Investigation of methods of birdsong imitation may expose alternative folk taxonomies based on vocalization type rather than morphology. As artifacts of human creativity in response to nature, warblish and the other methods of birdsong imitation described here merit interdisciplinary inquiry.