In 2014, approximately 95 of the nation’s 365 regularly-occurring bird species were considered to be ecologically dependent on forest. Only one forest species was considered likely to have been nationally extirpated in the last century: White-bellied Woodpecker Dryocopus javensis. Instead, the majority of forest species were considered at that time to have a good conservation status nationally, including species like the globally Vulnerable Fairy Pitta Pitta nympha, thanks in large part to a combination of the maturation of forests planted in the second half of last century and the warming climate, resulting in a gradual northward spread of warm temperate broad-leaved evergreen forest and the spread of mixed and oak forest (Moores et al. 2014).  Research since 2014 suggests that the national population of Fairy Pitta likely now exceeds 1,000 pairs – a substantial proportion of the global population. It is less clear whether bird species that are dependent on cold temperate coniferous forests –e.g., in higher areas of Seorak and Odae mountains – are as successful, although the provision of breeding boxes for Ural Owls Strix uralensis has resulted in increased numbers in the core of their ROK range, and perhaps also contributed to an increase in records south as far as Ulsan.​ ​ Either way, thanks to extensive reforestation efforts last century, forest is at present the second most extensive of the five main habitat types in the ROK, covering 5,933,300 ha in 2023 – approximately 58.5% of terrestrial habitats nationwide (ROK 2023). Although a massive improvement when compared to the first half of last century, this is a decline in forest area of about 775,000 ha since the 1980s, when 6,708,500 ha of forest were estimated (ROK 2023).   Although some forests are found in large near-inaccessible tracts (either because they are contained within the CCZ or in mountain ranges), many lowland forests are broken up by roads or are found in and around urban areas, where diversity tends to be rather low. In a few areas, however, wooded parks now supports an increasing number of species that originated largely from Japan or southern China, including Warbling White-eye Zosterops japonica and the recent colonist Chinese Blackbird Turdus mandarinus as well as species like Grey-backed Thrush Turdus hortulorum, which now breeds from hill forest down to near sea-level throughout most of the country. ​ In many areas nationwide, reforestation efforts depended on fast-growing conifers. However, many of the conifers planted last century have already died off (due in part to climate-related stresses) and have been succeeded by mixed forest or forest dominated by Quercus mongolica or Q.serrata (Choung et al. 2020, Hong et al. 2025).  ​ Currently, only 38.8% of the country’s forests are coniferous (in Hong et al. 2025), down from an estimated 40.5% of forest in 2014 (ROK 2014). More recent research suggests that almost a third of remaining coniferous forest might be replaced by mixed forest in only two decades, with the greatest rate of loss in Jeju and in the west (Kim et al. 2024). The majority of deciduous forest is currently dominated by Quercus mongolica, with such forest mainly dominant >800m.a.s.l. In many such forests, dominant species also “distributed with Q. mongolica included Pinus densiflora, Quercus variabilis, Acer pseudosieboldianum, Fraxinus rhynchophylla, and Quercus serrata… The dominant species distributed at the lower layer of Q. mongolica forests were Sasa borealis, Lindera obtusiloba, Rhododendron mucronulatum, Rhododendron schlippenbachii, Q. mongolica, and Fraxinus sieboldiana” (Kwon et al. 2022). ​ While the information base on forests is improving quite rapidly, our knowledge of forest birds still contains major information gaps. ​ For example, we know of very little research on population densities of even widespread breeding species, either within “forest” or within different types of wooded habitats.  We are also not aware of any detailed mapping of any forest-dependent bird species’ range within the ROK. Without better knowledge of habitat niche, territory size and distribution, it is not possible to make robust evidence-based population estimates that can then be used to measure changes in population due to changes in habitat area and quality. ​ Within this decade, can e.g., eBird data be used to identify forest types and bird distribution? Can targeted research projects develop usable estimates of population density by forest type? References Choung YS., Lee JS, Cho SY. & Noh JS. 2020. Review on the succession process of Pinus densiflora forests in South Korea: progressive and disturbance-driven succession. Journal of Ecology and Environment (2020) 44:16. https://doi.org/10.1186/s41610-020-00157-8 Hong M., Ko Y., Lee S., Song M. & Lee W.-K. 2025. Can Forest Management Improve Water Retention Conservation Under Climate Change? A Case Study of the Republic of Korea. Forests 2025, 16, 862. https://doi.org/10.3390/f16050862 Kim, E.-S., Jung, J. B., & Park, S. (2024). Analysis of Changes in Pine Forests According to Natural Forest Dynamics Using Time-series NFI Data. Journal of Korean Society of Forest Science, 113(1), 40–50. https://doi.org/10.14578/JKFS.2024.113.1.40 Kwon K C et al. 2022. Site Characteristics and Stand Structure of Quercus mongolica Forests in the Republic of Korea. Journal of Korean Society of Forest Science (한국산림과학회지) Volume 111 Issue 1 Pages.100-107. 2586-6613(pISSN) , 2586-6621(eISSN) Moores, N., Kim, A. & Kim R. 2014. Status of Birds, 2014. Birds Korea report on Bird Population Trends and Conservation Status in the Republic of Korea. Published by Birds Korea, September 2014. ROK. 2023. The Republic of Korea’s Fifth National Biodiversity Strategy (2024~2028). Published in December 2023.