Birds on the north coast of the Sea of Ariake

I. Seasonal changes in number of species and individuals on the representative birds

Abstract

Bird censuses were conducted approximately once a month in and around Yamato reclaimed land, Yamato Machi, Yamato Gun, Fukuoka Prefecture, i. e. on the north coast of the Sea of Ariake, from July 1974 to December 1976. Birds observed were 25 families including 99 species. The three of these families, Anatidae, Charadriidae and Scolopacidae included 47 species (47. 5% of all). The authors, therefore, decided to study seasonal changes in number of species and individuals of these three representative families.
1. The number of individual ducks (Anatidae) was greatest in winter, the number of species was greatest either in spring or autumn.
2. The highest number of individual plovers (Charadriidae) occurred in the autumn migratory season. The number of species was almost equal in spring and autumn (4 species in spring, while 5 species in autumn).
3. On the other hand, the number of individuals of sandpipers (Scolopacidae) was greater in the spring migratory season than in the autumn. The number of species was almost equal in spring and autumn (16 species vs. 18 species).
4. The record of bird observations on the north coast of the Sea of Ariake was compared with those in Osaka Bay, Tokyo Bay and the Gamou coast, Miyagi Prefecture. Among 35 species of shore birds observed on the north coast of the Sea of Ariake, 17 species were chosen (18 species were eliminated because of the rarity of observed individual), to compare the migratory types with those of the shore birds observed in the three districts above mentioned.
5. Six species (Charadrius mongolus, Pluvialis squatarola, Tringa erythropus, T. nebularia, T. brevipes, Xenus cinereus) on the Ariake Sea cost showed the same migration types as the in other three districts, and the other 11 species (Charadrius alexandrinus, Pluvialis dominica, Arenaria interpres, Calidris ruficollis, C. alpina, C. tenuirostris, Tringa glareola, Limosa limosa, L. lapponica, Numenius madagascariensis, N. phaeopus) on the Ariake Sea cost showed a difierent nigration type from these in the other three districts. As a result of taking the migration types into consideration, we might propose a fourth migratory course to the north, in addition to the three courses described by Kobayashi (1959). That is a route along the south coasts of the Japanese Islands. Two courses are described as the southward migratory route of the shore birds.
6. Whether migrating north or south, several opecies of shore birds seems pass the north coast of the Sea of Ariake migrate via Korean Peninsula, instead of passing through Honshu Island of Japan.