Interspecific hybridization occurs among birds, and closely related sister taxa tend to hybridize at a high rate. Genomic hybridization markers are useful for understanding the patterns and processes of hybridization and for conserving endangered species in captivity and the wild. In this study, we developed genomic hybridization markers for the F1 progeny of the sister taxa feral pigeons (Columba livia var. domestica) and endangered hill pigeons (Columba rupestris) (family Columbidae). Using whole-genome re-sequencing data, we performed genome-wide analysis for insertion/deletion (InDel) polymorphisms and validated using primers. We conducted polymerase chain reaction (PCR) and agarose gel electrophoresis to identify species-specific InDels. We produced eight F1 hybrids of hill and feral pigeons, and their samples were tested by re-performing analyses and sequencing using 11 species-specific InDel polymorphisms. Eight InDel markers simultaneously amplified two DNA fragments from all F1 hybrids, and there was no abnormality in the sequencing results. The application of genomic tools to detect hybrids can play a crucial role in the assessment of hybridization frequency in the wild. Moreover, systematic captive propagation efforts with hybrids can help control the population decline of hill pigeons.

Some seabirds commonly use artificially reclaimed lands, which are frequently located next to mainland environments, for breeding. Nest predation risk caused by birds or mammals from the mainland has negative influence on fitness-related costs and distribution of seabirds. Here, we sought to link potential factors, specifically those related to nest predation and nest environment, with breeding performance and colony movements of the Saunders's gull (Saundersilarus saundersi), a vulnerable species, on a large reclaimed area (1350 ha) in Incheon in Republic of Korea. This reclaimed area has experienced rapid changes in communities of nest predators from the mainland and vegetation ranging from halophytes to terrestrial plants after reclamation. Additionally, changes in the surrounding of used nest sites were retrospectively examined to determine whether colony movement was reversible in this reclaimed area. Our results indicated that high nest predation in a previous year induced colony movements in a consecutive year while the breeding colony exhibited a gradual reduction in clutch size. However, such movement after high nest predation seemed to be irreversible due to ongoing habitat degradation caused by construction and vegetation alteration. This study highlights that high nest predation may exert strong pressure on breeding colonies of Saunders's gulls. It also has anthropogenic impacts, leading to continuous dispersal of colonies to new areas for this vulnerable seabird in a reclaimed land.

Background: Hill pigeons (Columba rupestris) are close to local extinction (ca. less than 100 individuals) in South Korea where a variety of conservation management procedures are urgently required. Objective: This study was aimed at determining the conservation direction of captive propagation and reintroduction of hill pigeons using genetic information based on mitochondrial DNA. We also evaluated the extent of hybridization between hill pigeons and cohabiting domestic pigeons. Methods: We used 51 blood samples of hill pigeons from Goheung (GH), Gurye (GR), and Uiryeong (UR), and domestic pigeons cohabiting with hill pigeon populations. Genetic diversity, pairwise Fst, analysis of molecular variance, and haplotype network analysis were used to examine the genetic structure of hill pigeons. Results: Hill pigeons that inhabited South Korea were not genetically distinct from Mongolian and Russian populations and showed relatively low genetic diversity compared with other endangered species in Columbidae. The GR population that exhibited the largest population size showed lower genetic diversity, compared to the other populations, although the pairwise Fst values of the three populations indicated low genetic differentiation. The GH and GR populations were confirmed to lack hybridization, relatively, whereas the UR population was found to exhibit some degrees of hybridization. Conclusion: To conserve hill pigeons with low genetic diversity and differentiation in South Korea, the conservation process of captive propagation and reintroduction may require artificial gene flows among genetically verified populations in captivity and wildness. The introduction of foreign individuals from surrounding countries is also considered an alternative strategy for maintaining genetic diversity.

The latitudinal and elevational patterns of species richness of resident and migrant birds have been of interest to researchers over the past few decades, and various hypotheses have been proposed to explain the factors that may affect these patterns. This study aimed to shed light on the elevational distribution patterns of resident and migrant bird species richness by examining biotic and abiotic factors such as climate, and habitat heterogeneity using a piecewise structural equation model (pSEM). The overall pattern of resident species richness showed a decreasing trend with increasing elevation, whereas that of migrant species richness showed an increasing trend. The mid-peak pattern of species richness was affected by a combination of resident and migrant species and not by either resident or migrant species. Our results showed that resident species were distributed in lower elevation regions with higher mean spring temperatures, whereas migrant species were found in higher elevation regions with lower mean spring temperatures and higher overstory vegetation coverage. Although high elevation conditions might adversely affect the reproduction of migrant birds, higher overstory vegetation coverage at high elevations seemed to compensate for this by providing a better nesting and roosting environment. Despite the significance of habitat diversity and understory vegetation coverage in univariate linear regression models, multiple regression models of the interconnection of ecological processes demonstrated that mean spring temperature and overstory vegetation coverage were more explanatory than other variables.

Captive propagation and reintroduction are the major steps in the ex-situ conservation of locally extirpated endangered species in a historical region. In a species restoration project conducted in South Korea, we examined temporal changes in demographics and genetic diversity of oriental storks (Ciconia boyciana). Demographic and genetic data from 1996–2018 were analyzed for 80% of all captive and recently reintroduced individuals. Founder establishment and pair formation induced increases in population size and genetic diversity during the early stage of captive propagation. The degree of genetic diversity was found to become saturated and stable with long-term captive propagation. However, this might be a concern for future genetic diversity of both captive and reintroduced populations simultaneously due to the extraction of captive populations at the early stage of reintroduction. Our findings suggest that periodic evaluation of genetic diversity and selection for releasing individuals, using effective genetic markers, would assist in balancing the genetic diversity of the captive and reintroduced oriental storks at the early stage of reintroduction.