Abstract
We carried out an ecological and civil-engineering study on nest site selection of the three sympatric species of plovers, Charadrius dubius, C. placidus and C. alexandrinus on a flood-bed of the Kizu-river flowing through Kyoto Prefecture, Japan. The viewpoint of hydro-physics and animal ecology are applied and substrate size-sorting during the annual flood plays an important role here. We divided substrate size class around the plover nest site into six categories. C. alexandrinus, which generally nest on seacoast, significantly preferred fine texture “sand.” C. placidus and C. dubius significantly preferred larger texture “pebbles.” C. placidus tended to nest on larger substrate than C. dubius, although this difference was not significant. We discuss the physical mechanism driving the substrate distribution pattern on the sandbar, and suggest that flood-out is necessary for forming and maintaining the breeding habitat and coexistence of the three species of plovers.
