Abstract
We report nest site characteristics and seasonality of breeding behaviors observed in a Common Crossbill Loxia curvirostra population of Shimokita Peninsula, Northern Japan. Twenty nests were observed during the six breeding seasons from 2010/2011 to 2015/2016. Observation of banded birds confirmed that at least some crossbills were residential breeders in the study site. During the winter of 2012/2013 season, when ripe pine cones were scarce, we were unable to find any nests. The crossbills of this population, therefore, seem to opportunistic breeders, as reported for populations in other countries. Most of the nests were placed at the edge of black pine Pinus thunbergii forests. The nest height ranged from 8 to 18.4 m. The main breeding season was from November to April, which seems adapted to the timing of ripening pine cones
