Nest Site Selection of the Brown Dipper Cinclus pallasii

Abstract

A study on the nesting behavior and nest site selection of the Brown Dipper Cinclus pallasii was carried out in Yabe, Kumamoto Prefecture, central Kyushu, from 1982 to 1985.
1) Nest building occurred from August to April, with a peak in December and January. Nest building observed in August to October was not completed.
2) Male and female contributed equally in nest building. Any division of labor was not observed.
3) Of 53 nests found, 26 (49%) were built under the bridges, 13 (25%) on the overhanging banks or stone walls, and the remainder in the culverts, behind a water fall, in the disused drainage, on the rock, and so on. The use of bridges increased from 1982 to 1985. Nests built on the artificial structures were 64% of all.
4) Re-use of a nest over two successive breeding seasons was rare (only one case), but some nest sites were used for several years.
5) There was not significant difference in the breeding success between the cavity or covered nest sites and exposed ones.
6) The number of breeding pairs increased from six in 1982 to 13 in 1985. Available nest sites did not increase during the study period, but the area of shallows preferred as a foraging site by dippers increased due to the river improvement works, which may have caused the increase of breeding pairs.