📸 PhotoPhoto: BS Thurner Hof · CC BY-SA 3.0 · Wikimedia Commons Source
Scaly-sided Merganser
Mergus squamatus (Scaly-sided Merganser · コウライアイサ)
🇰🇷 Class I endangered wildlife (Korea) · Natural Monument (Korea) «Scaly-sided Merganser»
💡 Everyday Comparisons for Size, Mass & Speed
- 💡 Dongsong Reservoir in Cheorwon, Lake Daecheong in South Chungcheong Province, Lake Chuncheon, and the Namgang River in Jinju are listed by the Korea Heritage Service as winter observation sites for this duck.
- 💡 Its body length of 62 cm is slightly shorter than a badminton racket (about 67 cm).
Reference standards: coach bus ~12 m, mid-size car ~4.9 m, compact car ~1 t, basketball hoop 3.05 m, credit card 8.56 cm.
📖 1. Overview
The Scaly-sided Merganser is an Endangered (EN) duck that breeds in the Russian Far East and northeastern China, and visits South Korea very rarely in winter.
🦴 2. Anatomy & Morphology
Males have a glossy dark green head and neck with a long crest extending from the back of the head, and distinct scale-like markings along the flanks. The bill is long, slender, red, and serrated along the edges.
🔍 3. Ecology & Behavior
It dives underwater to catch fish and aquatic invertebrates, and nests in riverside tree cavities, laying 10–11 eggs.
🇰🇷 4. Connection to Korea
It is an Endangered Wildlife Class I species and was designated a Natural Monument on March 17, 2005. Small numbers have been recorded in winter at Dongsong Reservoir in Cheorwon, Lake Daecheong, Lake Chuncheon, and the Namgang River in Jinju.
📚 Sources & References
- • IUCN Red List EN (2025) — https://www.iucnredlist.org/species/22680488/244637355
- • 멸종위기 야생생물 Ⅰ급 · 천연기념물 «호사비오리» — 국가생물종목록(국립생물자원관) ktsn 120000001474 — https://species.nibr.go.kr/home/mainHome.do?cont_link=009&subMenu=009002&contCd=009002&ktsn=120000001474
- • IUCN Red List category EN — latest assessment at iucnredlist.org
- • Korean protection status: Class I endangered wildlife (Korea) · Natural Monument (Korea) «Scaly-sided Merganser»
- • doi.org — avilist.v2026
- • iucnredlist.org — 244637355
- • 국가생물종목록(국립생물자원관) ktsn 120000001474 — https://species.nibr.go.kr/home/mainHome.do?cont_link=009&subMenu=009002&contCd=009002&ktsn=120000001474
- • heritage.go.kr — culSelectDetail.do
- • wikidata.org — Q495159
- • commons.wikimedia.org — File:245 Schuppensäger 20091229.JPG
- • eaaflyway.net
- • heritage.go.kr — cul 1369904480000.html
- • tracyaviary.org — scaly-sided-merganser
- • encykorea.aks.ac.kr — E0075058
- • species.nibr.go.kr — general-search
- • Silhouette: PhyloPic — Kai Caspar · CC0 1.0 (Congeneric silhouette — Mergus merganser)
Recorded dimensions are widely cited representative estimates from public literature and may vary by study or specimen.