Avian species survey with citizen-science data in Janghang Wetland, Goyang, Republic of Korea

Abstract Background Monitoring of avian populations in Janghang Wetland, Goyang, Republic of Korea (ROK) is based on citizen science (also called community-based monitoring). This monitoring data can be used to track avian density, population status and waterbird census at local, national and regional levels. The Ministry of Environment (MoE) ROK has surveyed since 1999, including Odusan Unification Tower to Ilsan Bride, which connects the cities of Gimpo and Goyang along the Han River estuary. However, it has not covered Janghang Wetland, which is located in the Han River estuary at the transboundary between the two Koreas. The Janghang Wetland is a protected wetland in the Demilitarized Zone (DMZ) between the two Koreas. In 2019, Janghang Wetland was designated as a Flyway Network Site by Goyang City and the East Asian-Australasian Flyway Partnership. This Network site is a voluntary collaboration and includes many internationally significant wetlands for waterbirds that still lack formal national protection. In addition, it was designated as a Ramsar site in 2021. The wetland currently supports wintering population of White-naped Crane (Grusvipio), species listed as vulnerable and Tundra Bean Goose (Ansercygnoides), spring-autumn migration population of Swan Goose (Ansercygnoid), species listed as vulnerable and a breeding population of Black-faced Spoonbill (Plataleaminor), species listed as endangered in summer. New information We provide data that the Janghang Wetland is a significant area for migration and breeding for waterbirds; and that Han River estuary is also internationally important for waterbirds during the migratory bird season. We observed 14 orders, 42 families and 132 species. The surveys also observed the critically-endangered Black-faced Spoonbill (Plataleaminor), Swan Goose (Ansercygnoides), White-naped Crane (Grusvipio), Whooper Swan (Cygnuscygnus) and Peregrine Falcon (Falcoperegrinus). We also observed the Black-faced Spoonbill, Great Egret, Little Egret, Great Cormorant, Eastern Spot-billed Duck, Pheasant and Brown-eared Bulbul at the sensor camera point and White-naped Crane, Hooded Crane, Bean Goose, White-fronted Goose, Snow Goose, Swan Goose, Great Cormorant and Eastern Spot-billed Duck at the closed-circuit television camera point from the camera-trap surveys. Based on the species recorded, the survey area is of clear importance for biodiversity conservation.


Introduction
The Janghang Wetland is a site of international importance located in Han River estuary. It is an estuarine wetland teeming with a stretch of Salix koreensis (Korean willows), rarely seen in other brackish water zones of Korea. The Salix koreensis community has not only a symbiotic relationship with benthos, including Chiromantes dehaani, Sesarmops intermedius and Ilyoplax deschampsi, which are indicator species of a blackish water zone, but also plays a role in regulating temperature of the urban area, decreasing carbon and protecting the margins of the river. It serves as an important stopover site for more than 30,000 birds each year, providing habitat and food for winter visitors, such as Black-faced Spoonbill (Platalea minor), Hooded crane (Grus monachal), White-naped Crane (Grus vipio) and Bean goose (Anser fabalis . However, the current area of the Asia Waterbird Census does not include the westernmost part of the Han River estuary area, including Siman-ri Wetland in Gimpo-si (city) and Janghang wetland in Goyang-si (National Institute Biological Resource 2020, National Institute of Biological Resources 2022). In both areas, there are, at this time, thousands of geese, plus numerous other waterbirds. With this background, this work aimed to conduct an inventory of the waterbirds in the inner border area of Goyang in ROK, focused on the Janghang Wetland.

Additional information:
The survey result is provided in the supplementary material (Suppl. material 1).

Project description Title: Ecological Survey in Janghang Wetland
Personnel: The survey was led by a citizen-science group, including four experts who have experience over 10 years, 10 assistants who have experience over 5 years, one officer within local government and two ornithologists for identification and data preparation at research institutes. To ensure accuracy for the bird identification, we recorded photos and did peer-reviews. The survey was conducted over 11 months between April 2020 and March 2021 by ECO Korea, a citizen-science organisation. We gathered data during fortyfour surveys.

Study area description:
The study area is part of Han River Estuary Wetland Protected Area, designated on 17 April 2006 by the Ministry of Environment, ROK. The total area is 60,668 km (Fig. 1). In addition, the study area is a civilian-controlled area in the DMZ, where access to the public is restricted due to the threat of land mines and the Military Installation Protected Area.

Funding:
The project is supported by the Basic Science Research Program through the National Research Foundation of Korea, funded by the Ministry of Education (NRF-2021R1A6A1A10045235) and Han River Basin Environmental Office.

Sampling methods
Description: This study covered Janhang Wetland and the surrounding area along the Jayu-Ro (road).

Sampling description:
We focused counting on bird species found in open wetland habitats, as defined by the Ramsar Convention (e.g. along streams and waterways; the river edge). We covered five points with specific and secured areas (Fig. 2) and stayed for a particular time to survey with binoculars (8×32, Swarovski) and telescope (20~60×, Swarovski). We also did camera-trap surveys to record the cryptic species at the tidal channel, the inner area of Janghang Wetland, such as with a sensor camera (HP2X Hyperfire 2 Covert IR Camera) and a closed-circuit television camera at the submerged sleeping ground of the winter birds. During the surveys, we counted every individual bird, based on point surveys and line surveys that we either heard or saw from a slowly moving vehicle (average < 20 km/h) and walking in Janhang Wetland. We also did video analysis using camera trapping for the bird identification.  The name of the country or major administrative unit in which the Location occurs. locality The specific description of the place.
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coordinateUncertaintyInMetres The horizontal distance (in metres) from the given decimalLatitude and decimalLongitude describing the smallest circle containing the whole of the identificationReferences List of references (publications) used in the Identification.