Nest Site Selection of Six Heron Species in a Breeding Colony

Abstract

The author investigated nest site selection of six heron species in a breeding colony, Matsue city, Shimane Pref, San' in Region, Japan. The colony was located on a low hill facing to a bypass-highway, covered with a secondary forest, which was composed of Japan cedar (Cryptomeria japonica), Chestnut (Castanea crenata), Red pine (Pinus densiflora), etc. One-half fo nests were occupied by Nycticorax nycticorax, and there were a few nests of Egretta alba and Ardea cinerea. The nest distribution of the last two species showed a tendency to concentrate in the east-side of the colony, while those of Egretta ganetta, Egretta intermedia and Bubulcus ibis did a tendency to concentrate in the west-side of the colony. Two species nested mainly at the tops of trees of P. densiftora. On the other hand, N. nycticorax, E. garzetta, E. intermedia and B. ibis tended to select other tree species than above-mentioned trees. These species liked to nest in lower trees, and E. ganetta selected inside the crowns, while E. intermedia and B. ibis did near the tops of trees. N nycticorax nested widely within the colony and tended to select at the tops of trees. E. alba showed a significant nesting association with A. cinerea. B. ibis showed a significant nesting assosiation with E. ganetta and E. intemedia.