Creation and adaptive management of a wild bird habitat on reclaimed land in Osaka Port

We examined the efficacy of habitat creation for shorebirds on reclaimed land in Osaka Port. The Wild Bird Park was laid out on a reclaimed land in Osaka Port in 1983. A modern history of the area as a habitat for shorebirds can be divided into four stages. First, many shorebirds visited the tidal flat of 30 ha that emerged on the south part of the Sakishima, which had been reclaimed from the sea in 1941, but was abandoned between 1950 and 1958 [Notes on Osaka Bay Waders. Private Publishing (in Japanese with English abstract)]. Second, the tidal flat disappeared because of the start of the reclamation of the north part of Sakishima in 1958, and a salt marsh of 85 ha emerged in the north part between 1974 and 1982. Third, the salt marsh disappeared due to the construction and the Wild Bird Park was opened on a part of the salt marsh in 1983. The park had a planted area of 6.5 ha and a sandy area of 12.8 ha, which included two ponds and a lagoon. Fourth, one of the ponds was restored to a tidal flat in 1995 after consultation among the manager, NPO, and scientist as a result of the monitoring. The area of tidal flat increased from 0.2 to 2.6 ha, and the number of shorebirds increased from 205 (the average of 1991–1995) to 1042 (1996). The abundance and species richness of shorebirds is equivalent to those at the first stage (1950s). The species composition of benthic animals had also changed; the dominant group was Chironomid larvae during the second and third stages and Polychaetes during the fourth stage, and the species richness was greatest at the fourth stage. However, the tidal flat of the park had fewer brachyurans and mollusks than natural tidal flats in Japan. This might result in a lower abundance of large sandpipers at the fourth stage compared with that at the first and second stages.