Species-specific responses of forest birds to high-quality forest vegetation and forest cover during the breeding season in South Korea

Understanding how forest birds respond to habitat quality and quantity is essential for forest biodiversity conservation. We used nationwide data from the Fifth National Ecosystem Survey of South Korea (2019–2023), compiled for approximately 3.8 × 4.6 km grid cells, to assess species-specific associations between forest bird occurrence and forest quality and forest cover during the breeding season, while accounting for mean elevation within each grid cell. Forest quality was defined as the proportion of forest areas classified under vegetation conservation grades 1 and 2 relative to the total forest area within each grid cell, representing forests with high conservation value and relatively intact natural vegetation. We fitted species-specific logistic regression models for 57 forest- and woodland-associated bird species and applied Benjamini–Hochberg false discovery rate (FDR) correction separately to each variable. Forest quality was significantly associated with the occurrence of 17 species, including three positive and 14 negative associations. Forest cover showed significant positive associations with the occurrence of 44 species, highlighting the broad importance of habitat quantity. Mean elevation was significantly associated with the occurrence of 28 species, indicating that broad elevational gradients also influenced forest bird occurrence. These results indicate that forest bird species respond differently to forest quality, forest cover, and elevation. Our findings suggest that forest biodiversity conservation in South Korea should address both the qualitative and quantitative aspects of forest habitats.