- 日本鑑識科学技術学会誌 (ISSN:13428713)
- vol.9, no.2, pp.95-102, 2004 (Released:2007-11-07)
In a recent murder case, many feathers were left at the crime scene and collected for analysis. It seemed they were likely left from the suspect's torn jacket. Goose and duck downs are commonly used for clothes and bedclothes, especially in high quality goods where goose feathers are used most often. Unfortunately, at the time of the murder there were few studies in Japan about down identification. This paper presents how to identify goose and duck downs by microscopy. Ten downs were removed at random from each stuffed bird from sixty-one species at the prefectural museum. Ten downs were removed at random from ten geese and ten ducks, respectively, at the prefectural farm. Therefore, the authentic sample set (family or species known) included ten downs each from eighty-one birds, representing sixty-three species. In addition, two hundred goose downs and two hundred duck downs were obtained from samples supplied by the Japan Spinners Inspecting Foundation in Tokyo. These down samples were examined microscopically with respect to eight morphological characteristics: full length, color, node shape, maximum node width, maximum node interval, node distribution, node density (number of nodes per mm) and pigment distribution. Morphological data from geese were compared with ducks and analyzed statistically using F-test. Duck and goose downs are identified primarily by their triangular nodes. In birds of the sixty-three species other than those from the duck and geese species, triangular nodes were found only in the Anatidae, Columbidae and Psittacidae families. Fortunately, it was quite simple to distinguish the families by the node distribution along the shaft of the barbules. For example, the Anatidae family has triangular nodes only toward the tip of the barbule, the Columbidae family has them mainly toward the base of the barbule, and the Psittacidae family has them uniformly distributed along the shaft of the barbule. Based on feather nodes, both goose and duck can be placed in the Anatidae family. Nevertheless, they can be distinguished. Goose has wider maximum node intervals than the duck, usually more than fifty-five micrometers. On the other hand, duck has higher node density than the goose, more than sixteen per mm. Statistical analysis using the F-test showed that the maximum node interval and node density were useful characteristics for distinguishing a goose from a duck down.