Seasonal Change in Breeding Success of the Black-Billed Magpie Pica pica sericea

Abstract

Breeding success of the Japanese race of the Black-billed Magpie (Pica pica sericea) was studied in a rural habitat between 1988 and 1992. Most clutches were laid in March and April every year. The mean clutch size (6.19) and mean number of hatchlings (3.88) were within the ranges of values for European and North American races. The nesting success was low, with only 17% of pairs fledging young. Predation, mainly by crows, accounted more than 80% of the failures. Predation rate was not related to brood size. Nesting success declined seasonally, due to an increase in nest predation by crows. The nutritional state of nestlings did not change seasonally.