Print ISSN : 1347-0558
  • Toru NAKAHARA, Katsuhisa MIYAHARA, Yoshito MORIMOTO, Kazuya NAGAI
    2024 年 23 巻 1 号 p. 3-12
    発行日: 2024年
    公開日: 2024/01/29
    ジャーナル フリー

    The distribution of Light-vented Bulbul Pycnonotus sinensis has been expanding in East Asia in recent decades. Since the 2000s it has even bred sporadically in mainland Japan, in both Kyushu and Honshu, which it may have reached by natural dispersal. In this study, we aimed to clarify the origins of the birds seemingly colonising western Japan. First, we reviewed observations of the species in South Korea and western Japan and clarified spatiotemporal changes in its distribution since the 2000s. Second, we captured Light-vented Bulbul in Kitakyushu, where it has been observed since 2017 and compared its morphological characteristics and ND2 sequence in the mitochondrial DNA with those of other populations. We obtained three key results: 1) the number of observations of the Light-vented Bulbul has increased since the late 2000s in western Japan, which is consistent with the timing of its expansion in South Korea; 2) individuals captured in Kitakyushu had morphological characteristics similar to those of P. s. sinensis in China; and 3) we observed multiple haplotypes in the Kitakyushu population, which were all included in the cluster of P. s. sinensis and P. s. hainanus, but not included in the cluster of P. s. formosae in Taiwan, P. s. orii in the Yaeyama Islands, or in the unidentified subspecies on Okinawajima Island. These results suggest that China is the origin of individuals recently observed in western Japan, and it is considered likely that dispersal has occurred naturally from the Eurasian continent via the Korean Peninsula. Since the Light-vented Bulbul has already become established, and is still increasing in numbers, in southeastern South Korea, observations are also likely to increase in western Japan.

  • Akihiko KOGA, Kornsorn SRIKULNATH
    2024 年 23 巻 1 号 p. 13-20
    発行日: 2024年
    公開日: 2024/01/29
    ジャーナル 認証あり

    Two Carrion Crow Corvus corone kept at a bird conservation facility in Niigata, Japan, had entirely white plumage, pink feet and beaks, and red eyes, indicative of a lack of melanin pigments. Tyrosinase, an enzyme essential for melanin biosynthesis, is encoded by the TYR gene. Sequencing analysis of TYR of the white individuals revealed a deletion of 18 consecutive nucleotides, leading to the loss of six amino acids from the tyrosinase protein. The body color mutation is likely to have been caused by this 18-nucleotide deletion. White crows have been found frequently in the Niigata region for over 30 years. The deletion mutant gene is considered to persist in the natural Carrion Crow population of this region, mainly in heterozygous carriers and primarily owing to random genetic drift.