Identification of Geese, Swans and Ducks by the Barbule Structure of Feathers

Abstract

Variation in the barbule structure of the downy barbs of 30 species of Anseriformes occurring in Japan (six species of geese, one species of swan, and 23 species of ducks, including some domestic forms) was examined to confirm whether or not there were consistent differences among geese, swans and ducks. The distribution of the triangular nodes within one single barbule showed different tendencies among these three groups, although there was considerable overlap. The triangular nodes of ducks were clearly wider than those of geese and swans, but the latter two groups were mutually indistinguishable in this character. The barbules of swans were distinctly shorter than those of the other two groups. Similar tendencies were also found in the feathers of the domestic forms. Thus, this study suggests that it is possible to distinguish among geese, swans and ducks based on the barbule structure. This study also showed that the triangular nodes were absent in primary feathers, alula, primary-coverts, axillaries and very small feathers around the beak in most of examined species. Some species also lacked the triangular nodes in feathers around the oil gland, secondary and tertiary feathers and greater wing-coverts. In fledglings, all of the body feathers lacked the triangular nodes.