The Relationships of Sparrows in the Genera Ammodramus, Passerherbulus, and Ammospiza with a Description of a Hybrid Le Conte's × Sharp-Tailed Sparrow

Abstract

THE first and second editions of the A.O.U. Check-list (1886, 1895) list the Henslow's Sparrow (now Passerherbulus henslowii) and the Le Conte's Sparrow (now Passerherbulus caudacutus) in the subgenus Coturniculus of the genus Ammodramus with the Grasshopper Sparrow (now Ammnodramus savannarum). When Ridgway (1901) raised the subgenera (Passerculus, Centronyx, Coturniculus, and Ammodramus) of Ammodramus to generic rank, he separated the Henslow's and Le Conte's Sparrows from the Grasshopper Sparrow and placed them with the former members of the subgenus Ammodramus, the Sharp-tailed Sparrow (now Ammospiza caudacuta) and the known Seaside Sparrows (now Ammospiza maritima and nigrescens), a treatment later followed by the A.O.U. (1903). The Ammodramus group remained intact, despite being renamed Ammospiza (Oberholser, 1905) and then Passerherbulus (Stone, 1907), until Oberholser (1917) split the group into four genera: Thryospiza for the Seaside Sparrows, Ammospiza for the Sharp-tailed Sparrow, Passerherbulus for the Le Conte's Sparrow, and Nemospiza for the Henslow's Sparrow. Subsequently the A.O.U. (1931) recognized the genus Ammospiza containing the Sharp-tailed and Seaside Sparrows, the genus Passerherbulus containing the Le Conte's and Henslow's Sparrows, and the genus Ammodramus, containing the Baird's (A. bairdii) and Grasshopper Sparrows. No changes have been made since, and as yet no diagnoses exist for these genera as presently constituted. More recently Tordoff and Mengel (1951) questioned the present classification when they discovered that the prealternate molt of the Le Conte's Sparrow was extensive and thus more like that of the Sharp-tailed Sparrow than that of the Henslow's Sparrow. Graber (1955) actually transferred the Le Conte's Sparrow to Ammospiza on the basis of the similarity of the juvenal plumages of the Le Conte's and Sharp-tailed Sparrows. With the discovery of a hybrid between the Le Conte's and Sharp-tailed Sparrows (described below), it seems appropriate to consider the evidence of molt, plumage, and voice bearing on the relationships of these species. Molt.-The descriptions of the molts of the species being considered are generally incomplete or erroneous. Detailed studies for most species have yet to be made. The best that can be done now is a brief comparison of what is known.