Effects of environmental factors and intraspecific niche overlap on the body and ecological characteristics of red-tongued pit vipers (Gloydius ussuriensis).

The body condition of a snake species provides important physiological, morphological, and ecological information that elucidates its habits, life cycle, and competitive relationships. We measured the body size and condition of the wild Gloydius ussuriensis population in South Korea from 2018 to 2022, analyzed the degree of intraspecific niche overlap, and identified the geographic and climatic factors affecting their body condition. We found that the females were longer than the males. The body condition index (BCI) of G. ussuriensis differed depending on sex and season; the BCI of the females and males was highest in August and October, respectively. Environmental factors related to altitude and temperature affected the body condition of G. ussuriensis; BCI increased as the mean annual temperature and winter temperature increased; however, it increased when the annual temperature range decreased. The mean Pinaka index was 0.96, indicating a high degree of niche overlap; however, the niche overlap among the neonates was less than that among the adults and juveniles. To elucidate the causes of niche overlap and mechanisms behind the intraspecific competition among G. ussuriensis individuals, the habitat and utilization of food resources at different development stages of G. ussuriensis should be further investigated.

Complete mitochondrial genome of Asian koel Eudynamys scolopaceus (Aves: Cuculiformes) from South Korea.

In this study, we analyzed the complete mitochondrial genome of Eudynamys scolopaceus using Illumina and Pacbio next-generation sequencing. The total length of the mitogenome was 18,170 bp and contained 13 protein-coding genes (PCGs), two ribosomal RNAs, 22 transfer RNAs, a non-coding control region, and two repeat regions. The order of the genes and genome structure were the same as those in a previous publication in other Cuculidae species. A phylogenetic tree constructed with 13 PCGs indicated that E. scolopaceus is closely related to Urodynamis taitensis and genus Cuculus.

Foraging Strategy of Black-faced Spoonbill During Breeding Period in Rice Fields of Korea.

Rice fields are important habitats for a variety of water birds, and their importance is increasing with the destruction of natural wetlands. This study was conducted to understand the foraging strategy of the black-faced spoonbill, an internationally endangered species, in rice fields. To achieve this objective, the feeding success rate of black-faced spoonbills in rice fields was analyzed considering the species' feeding behavior, environmental factors, and external factors. The number of sweeps per minute and number of steps per minute were evaluated as features of feeding behavior; rice field type, water level, and rice height as environmental factors; and the size of a flock and number of other species in the fields when black-faced spoonbills were feeding as external factors. The feeding success rate of the black-faced spoonbills increased as they were feeding while moving at a fast pace in a rice field with a water level of 10 cm or below, rice height of 15 cm, and without herons (competitor species). These factors may be an effective strategy to increase the probability of food acquisition by black-faced spoonbills in rice fields. Therefore, to allow black-faced spoonbills during breeding season to use the rice fields for feeding, it is necessary to maintain a water level of 15 cm or less before transplanting rice. Moreover, the use of pesticides must be minimized to increase abundance of the food resources in rice fields.

The establishment of ecological conservation for herpetofauna species in hotspot areas of South Korea.

Understanding the geographic distribution of species is crucial for establishing protected areas. This study aimed to identify the preferred habitat environment of South Korean herpetofauna using distribution point information, providing the information necessary to protect their habitat by establishing a species distribution model. We found that climate variables in the region where 19 amphibians and 20 reptiles were distributed correlated with the altitude, suggesting that altitude had a major influence on their distribution. The species distribution modeling indicated that 10-12 amphibian and 13-16 reptile species inhabit the Gangwon-do region, forming hotspot areas in the eastern and western regions around the Taebaek Mountains. Some of these hotspot areas occurred in the Demilitarized Zone and national parks, which are government-managed ecological conservation areas. However, some hotspot areas are vulnerable to habitat destruction due to development and deforestation as they are not designated conservation areas. Therefore, it is necessary to establish new conservation areas with a focus on herpetofauna after confirming the actual inhabitation of species through precise monitoring in predicted hotspot areas and designating them as protected areas. Our results can serve as important basic data for establishing protection measures and designating protected areas for herpetofauna species.

Impact of rice paddy agriculture on habitat usage of migratory shorebirds at the rice paddy scale in Korea.

Approximately 58 shorebird species, including endangered and threatened species, use various habitats while traveling on their long-distance migratory routes in the East Asian-Australasian Flyway (EAAF). Coastal rice paddies in midwestern Korea, which are located in the EAAF, serve as inland wetlands and provide important stopover sites for long-distance migratory shorebirds. We studied how shorebird population density is affected across periods, time since habitat formation, and field type, at the rice field scale. The shorebirds most frequently observed in rice paddies were, in order, black-tailed godwits (Limosa limosa), common greenshanks (Tringa nebularia), and wood sandpipers (T. glareola). Black-tailed godwits and wood sandpipers were affected by time since formation, field type, and water level, whereas field type affected common greenshanks. We propose that (1) flooding time, (2) shallow water level, (3) harrowed field type, and (4) 5-7 days of management intervals at paddy fields are important factors influencing shorebird species density, although all the factors did not influence common greenshank density. We propose that environmental characteristics derived from field management in rice paddies influence habitat use by migratory shorebirds. These factors need to be considered to systematically protect and manage shorebirds that use rice paddies as stopovers during their migration events.

Effect of different management techniques on bird taxonomic groups on rice fields in the Republic of Korea.

Many bird species rely on the ecological functions of rice field habitats (e.g., paddy, levee, road, and ditch). However, recent intensive practices are causing rice fields to provide fewer suitable habitats. This study examined bird habitat usage and how it is affected by cultivation methods (e.g., eco-friendly vs conventional fields). Eco-friendly and conventional rice fields in the midwestern region of the Republic of Korea were surveyed from January 2014 to December 2016, and the species presence, number of birds, and locations of observed habitats were recorded. It was found that shorebirds and herons used more eco-friendly rice paddies with lower or no pesticide and/or herbicide use, while waterfowl used paddy habitats more than the other habitats, regardless of the amounts of pesticides and/or herbicides used. Land birds used ditches or roads in conventional rice fields more than those in fields that used pesticides and/or herbicides. Pesticide and/or herbicide use affected bird taxonomic groups differently. Consequently, the use of habitats by different bird taxonomic groups varied depending on the crop cultivation as well as the cultivation methods. These results provided valuable information for managing rice fields, which serve as habitats for birds.

Complete mitogenome and phylogenetic analysis of two species (Mareca penelope and Mareca falcate).

We determined the complete mitogenomes of two wigeons, Mareca penelope (16,603 bp) and Mareca falcata (16,597 bp) of the family Anatidae using Illumina next-generation sequencing to better understand phylogenetic relationships. Both species consisted of 37 genes (13 protein-coding genes), two ribosomal RNAs, 22 transfer RNAs, and one control region. A + T content (M. penelope 51.25%, M. falcata 51.2%) was slightly higher than G + C content (M. penelope 48.75%, M. falcata 48.8%). Phylogenetic analysis based on 13 concatenated PCG sequences indicated that M. penelope and M. falcata belong to the Mareca genus, with high bootstrap values.

Effects of Pesticide Use on the Distributions of Grey Herons (Ardea cinerea) and Great Egrets (Ardea alba) in Rice Fields of the Republic of Korea.

Pesticide use is known to have a negative impact on the habitat use of birds. The decomposition of residual pesticides causes a drastic decrease in the biomass of wildlife food sources, indirectly affecting the ecosystem. In this study, we investigated the effects of pesticide use on the distributions of grey herons (Ardea cinerea) and great egrets (Ardea alba) in rice fields in the Republic of Korea. From early May to mid-June in 2015 and 2016, we recorded the abundance of these birds and their prey (loaches, other fish, tadpoles, and benthic invertebrates) and investigated their dependence on rice agricultural practices (eco-friendly vs conventional) and field types (harrowed, plowed, or transplanted). We found that both grey herons and great egrets preferentially used transplanted fields. Grey herons were observed more in conventional rice fields, while great egrets were observed more in eco-friendly rice fields. This may be driven by the distribution of their preferred prey types; we observed a higher density of tadpoles (the prey type favored by grey herons) in conventional fields and a higher density of loaches (the preferred prey of great egrets) in eco-friendly fields. Pesticides drive these patterns both directly and indirectly; pesticide use in conventional rice fields directly suppresses the abundance of loaches, which frees the tadpole population from predation pressures and indirectly boosts their abundance in conventional rice fields. Our findings suggest that the distributions of grey herons and great egrets vary depending on food availability and are directly and indirectly influenced by pesticide use.

Flexible Behavior of the Black-Tailed Godwit Limosa limosa is Key to Successful Refueling during Staging at Rice Paddy Fields in Midwestern Korea.

Successful refueling at staging sites is essential for the survival and reproduction of migratory birds. Understanding their staging ecology is therefore crucial for the conservation of migrant species. Rice fields in the mid-western region of the Korean Peninsula serve as staging habitats for the black-tailed godwit (Limosa limosa). We examined the behavior of staging black-tailed godwits in rice fields located in the East Asian-Australasian Flyway during their northward migration. Specifically, we tested the effect of flock size and water level on the foraging, vigilance, and resting behaviors of black-tailed godwits. Our observations revealed that as flock size increased, stepping rate, pecking rate, and vigilance duration decreased, while probing rate, preening duration, and foraging efficiency increased. Stepping and pecking rates increased at low water levels, compared with high water levels. We determined that the behavior of black-tailed godwits at the staging site is influenced by flock size and water level. These observations suggest that black-tailed godwits form larger flocks to increase foraging efficiency by lowering individual-level vigilance, and to spend more time on preening, which is critical for flight and survival. It can be also inferred, based on the shift in primary foraging mode between probing and pecking depending on the water level, that they obtain higher foraging efficiency by flexibly adapting their foraging mode to the conditions in rice fields that are subject to agricultural activities. Our results are expected to serve as basic data for establishing efficient management strategies for anthropogenic habitats for the conservation of migratory shorebirds such as black-tailed godwit.

Does Nest Predation Influence Colony Movements of Saunders's Gulls (Saundersilarus saundersi) in a Reclaimed Land Area?

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.