Breeding distribution and habitat of Yellow-breasted Bunting before and during its population collapse in Hokkaido, northern Japan

Abstract

Yellow-breasted Bunting Emberiza aureola was a once an abundant summer migrant in the Northern Palearctic, but its population collapsed during the 1990s. The aim of this study was to clarify the breeding distribution of Yellow-breasted Bunting before and during the population collapse periods in Hokkaido, and then, I examined the habitat characteristics including vegetation and elevation. Distributional data were collected through a questionnaire survey of birdwatchers and from published data. In total, 5,264 observation records were collected. These data were summarised into 240 distribution points on a 10-km square scale. The distribution points were widely spread in coastal areas and in the middle and lower reaches of rivers and were abundant in the Eastern and Northern areas but fewer in the Western and Southwestern areas of Hokkaido. Yellow-breasted Bunting was mainly distributed in wetland vegetation, which might be its most important habitat. Natural grassland or anthropogenic habitats such as pastureland or crops, including rice and weedy fields, were also of major importance. From the elevation survey, Yellow-breasted Bunting occurred mainly in the range of 0–99 m above sea level, with its main habitat defined as lowland. Although the current population status of Yellow-breasted Bunting is still severe, the distribution map and habitat investigation revealed by this study will provide some important evidence for considering future conservation measures.