Nestling Diet and Prey Selection of the Japanese Wagtail Motacilla grandis.

Abstract

Nestling diet of Japanese Wagtails (Motacilla grandis) was investigated by the neck ligature method and compared with the food availability in their feeding habitat during the breeding season of 1999 in Higashi Hiroshima, western Japan. Nestling diet comprised of 85.5% insects, 14.2% arachnids and 0.3% chilopods in individual number basis. Odonata order comprised nearly one-fourth of the diet in dry weight basis. Diptera, Lepidoptera, Coleoptera, Orthoptera and Arachnida were also important contributors to the total prey weight. Chironomidae and Ephemeroptera families were the most numerous prey items but their contribution to the total prey weight was small. Electivity indices indicated that the Japanese Wagtail prefer certain prey items (Libellulidae, Tipulidae, Dytiscidae) when collecting prey for the nestlings.