Rare and endangered Scaly-sided Merganser recorded in Ba Be National Park

05/03/2025

In March 2025, researchers from the Institute of Tropical Ecology at the Joint Vietnam-Russia Tropical Science and Technology Research Center recorded a pair of Scaly-sided Merganser (Mergus squamatus Gould, 1864) at Ba Be Lake, located within Ba Be National Park, Bac Kan Province. The birds were observed foraging during a migratory stopover. This species is classified as rare and highly endangered, facing a significant risk of extinction.

The Scaly-sided Merganser (Mergus squamatus Gould, 1864) belongs to the Anatidae family within the order Anseriformes. This is one of the birds with a fairly large body size, ranging from 52 cm to 58 cm. The male features a red bill and legs, green-black head with a crest of black feathers, a black upper body, and a white breast and belly. Its flanks are adorned with light black-scaled feather patterns. The female has a golden-brown head and crest, a light gray upper body, and a white throat. The sides of the breast and neck are marked with light gray-scaled feathers.

The Scaly-sided Merganser inhabits large rivers, lakes, and wetlands, ranging from lowland areas to elevations of approximately 500 meters above sea level. Its diet consists predominantly of fish and various aquatic organisms. Globally, the species is distributed across South Korea, North Korea, Japan, Myanmar, Thailand, China, Siberia, and the Ussuri region of Russia. In Vietnam, approximately 26 species of wild ducks have been recorded as either residents or migratory visitors. Previous records indicate that the Scaly-sided Merganser has previously been observed stopping over during migration in the northeastern and northwestern regions of the country.

Currently, the species is experiencing a severe population decline, driven by habitat degradation, reduced food availability, and illegal hunting during migration. Experts estimate that fewer than 50 individuals pass through Vietnam during migration. Under IUCN Red List criteria C2a(i), the species is classified as Endangered (EN), indicating a high risk of extinction. It is also listed in Appendix II of the Convention on Migratory Species (CMS).

In Vietnam, the species is included in Appendix IIB of Government Decree No. 84/2021/NĐ-CP, which governs the protection of endangered wildlife and enforces the Convention on International Trade in Endangered Species (CITES). Furthermore, the 2025 edition of the Vietnam Red Data Book classifies this species as Critically Endangered (CR), highlighting its urgent conservation priority.

To effectively conserve and protect the Scaly-sided Merganser as well as other wild bird species, it is essential to implement strict management and conservation measures. This includes the rigorous enforcement of Directive 04/CT-TTg (2022) issued by the Prime Minister, which outlines urgent tasks and solutions for the preservation of wild and migratory birds in Vietnam. According to Article 234 of the 2015 Penal Code (as amended in Clause 57, Article 1 of the 2017 Revised Penal Code), the illegal hunting of the Scaly-sided Merganser may result in monetary fines or imprisonment ranging from 7 to 15 years.