Breeding of the black woodpecker in plantation forests in Hokkaido, Japan, including retention-harvested stands: a comparison of nest trees and nesting habitats across Japan and Europe

In Japan, the black woodpecker (Dryocopus martius) is known to breed mainly in natural forests. This study reports black woodpecker breeding records from plantation forests, including retention-harvested stands (harvested stands with broadleaved tree retentions) in Hokkaido. It compares nesting habitat characteristics with previous studies from Hokkaido, the Tohoku region, and Europe and provides implications for forest management to conserve the species in Hokkaido. At Japan’s first retention forestry site established in 2013, breeding was first confirmed three years after harvesting in retained broadleaved trees and has since been recorded only in the medium- (50 trees/ha) and large- (100 trees/ha), but not the small-amount (10 trees/ha) retention treatments. Multiple black woodpecker breeding records were recorded in plantations in central Hokkaido. Excluding retention-harvested stands, almost all nest trees in plantations were planted trees, but two nest trees found in Japanese larch (Larix kaempferi) plantations were naturally regenerated broadleaved trees. The mean tree density and basal area (BA) within a 10 m radius of nest trees were 430.3 trees/ha and 20.4 m2/ha, respectively, indicating relatively open conditions around nest trees. Within a 500 m radius of nest trees, plantation forests were the dominant land-cover type at all but one site. Our findings and those of previous European studies suggest that retention forestry could be a beneficial management approach that accommodates this species by retaining trees that meet their nesting requirements. We also recommend considering potential black woodpecker nesting in plantations older than 40–45 years.