The Black-billed Magpie, Pica pica sericea, was introduced in Japan from Korea about 400 years ago. It inhabits a restricted area in northern Kyushu, but has relatively high nesting density in some areas (> 20 pairs per km²). Most nests are built in the vicinity of human habitation, even in the midst of cities. Most clutches are laid in March and April. Mean clutch size (6.2) and mean number of hatchlings (4.2) are within the ranges of values for European and North American races. Nesting success is low, with only 18% of clutches surviving to fledge. Predation, mainly by crows, is a major cause of failure, accounting for 81% of clutch loss and 84% of brood loss. Low nesting success may have taken place in recent years. Nests on utility poles are more successful than those in trees. Nesting on utility poles has been increasing, occupying more than 50% of total number of nests. The range of the Black-billed Magpie has been gradually expanding in Japan.
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