The impact of forest characteristics, and bird and insect diversity on the occurrence of the Great Spotted Woodpecker Dendrocopos major and Grey-headed Woodpecker Picus canus in South Korea

ABSTRACT Capsule Although the Great Spotted Woodpecker Dendrocopos major and Grey-headed Woodpecker Picus canus have overlapping ranges in South Korea, they occur in areas with different forest structures and the occurrence of each species is associated with their main foods. Aims To investigate the biotic factors related to the occurrence of the Great Spotted Woodpecker and the Grey-headed Woodpecker, two species that frequently inhabit overlapping regions in South Korea. Methods Correlations between the occurrence of the two woodpecker species, forest characteristics, and bird and insect species richness were evaluated based on large-scale public data from the National Ecosystem Survey and a Forest Type Map. Results The occurrence of Great Spotted Woodpeckers was associated with forest stands with at least 75% coniferous trees, whereas the occurrence of Grey-headed Woodpeckers was negatively associated with forested areas with canopy cover exceeding 50%. The occurrence of both species was strongly and positively correlated with the species richness of forest birds. The occurrence of Great Spotted Woodpeckers was correlated with the species richness of Coleoptera, while that of the Grey-headed Woodpecker was correlated with the species richness of Hymenoptera and Diptera. Conclusion The co-occurrence of the two woodpecker species within shared habitats can be explained by low competition due to differences in preferred forest characteristics and in the food sources used by each species.