Hwat dostu godes a-mong monne?
Na mo pene dop a wrecche wrenne.
(What good do you do among men?
No more than does a wretched wren.)
(The Owl and the Nightingale, Middle English poem, 13th century, lines 563–566; Wells 1907)
Most bird species possess 12 rectrices in six pairs, although the number of rectrices varies among all species from 6 to 32 (Van Tyne and Bergen 1976). Within a species, variations from the typical number of rectrices also occur, commonly in some species, and it is this type of variation that has probably attracted most attention. Audubon (1831:139, 140), for example, reported a female Carolina Parakeet (Conuropsis carolinensis) with a pair of supernumerary rectrices; he recognized it as an individual aberration and chose to highlight it in his painting of this species. Somadikara (1984) used the term “polyrecticly” for supernumerary rectrices, and Hanmer (1985) coined the term “anisorectricial” for an abnormal number of rectrices, whether in an asymmetrical or symmetrical context.