Birds Of Japan 33:Eurasian Teal-日本の野鳥33: コガモ

The Eurasian teal (Anas crecca), also known as the green-winged teal, is a small species of dabbling duck found across Europe, Asia, and parts of North America. Here's some key information about this species:

Physical Description

• Size: One of the smallest ducks, measuring about 33-38 cm (13-15 inches) in length, with a wingspan of 58-64 cm (23-25 inches).
• Weight: Typically around 250-400 grams (8.8-14.1 ounces).
• Male (Drake): The male has a distinctive appearance with a bright greenish patch on the wing (from which it gets the name "green-winged teal"), a chestnut-colored body, and a dark green head. In breeding season, it also sports a prominent white vertical stripe running down the body.
• Female (Hen): The female is more muted in color, with mottled brown plumage, a pale face, and a small, inconspicuous patch of green on the wing. She resembles many other duck species but is generally smaller and more slender.

Habitat and Distribution

• Range: The Eurasian teal is found across Europe and much of Asia, from the British Isles to Japan and Siberia. It is also present in parts of North America, particularly in winter when migrating.
• Habitat: Prefers wetlands, including shallow lakes, ponds, marshes, and rivers. It can also be found in estuaries and coastal lagoons, especially during migration periods.
• Migration: A migratory species, the Eurasian teal winters in southern Europe, the Middle East, and parts of Asia. Some populations, especially in the more temperate zones, are partial migrants, while others migrate long distances.

Behavior and Diet

• Feeding: The Eurasian teal is a dabbling duck, meaning it feeds mainly on the water's surface or dips its bill into the water to forage for seeds, aquatic plants, algae, and small invertebrates. During migration, they may also forage in wet meadows or rice paddies.
• Behavior: They are often found in small groups or pairs, especially outside of the breeding season. They are known for being agile in flight and tend to form large flocks during migration.
• Communication: The call of the Eurasian teal is a soft "quack," but the male is known for a whistling sound during courtship.

Breeding and Nesting

• Breeding Season: Typically occurs in late spring and early summer. Mating pairs form in the winter and remain together until after the young are raised.
• Nesting: The female usually builds a hidden nest in dense vegetation near water. It is made of grasses, reeds, and down feathers. She lays between 6-12 eggs, which are incubated for about 23-25 days.
• Young: Ducklings are precocial, meaning they are born with their eyes open and are able to swim and feed almost immediately after hatching. They are highly dependent on the mother for the first few weeks.

Conservation Status

• IUCN Status: The Eurasian teal is listed as Least Concern by the International Union for Conservation of Nature (IUCN). However, some populations are subject to pressures from habitat loss, hunting, and environmental changes.

Interesting Facts

• The male Eurasian teal's distinctive green wing patch is one of the key identification features, and it is especially vibrant in breeding plumage.
• The species has a relatively long lifespan for a duck, living up to 20 years in the wild, though most don't reach this age due to predation or hunting.

In terms of importance, the Eurasian teal is considered a "game" species in some regions and is hunted for sport, although it is generally not at risk due to its wide distribution and adaptability.

コガモ（Eurasian teal、学名: Anas crecca）は、小型のカモ科の鳥で、日本を含むユーラシア大陸に広く分布しています。コガモは、世界中の湿地帯、湖、池、川などの浅い水域で見られ、渡り鳥として知られています。

特徴

• 体長: 約34–38 cm
• 体重: 約300–450 g
• 翼開長: 約55–60 cm

コガモは、ダブリングカモの一種で、首を水に突っ込んで植物や小さな水生昆虫を食べます。繁殖期におけるオス（ドレーク）は非常に鮮やかな色合いが特徴で、頭部に緑色の斑点があり、胸は赤褐色、体には褐色の斑点が見られます。メスは、全体的に茶色っぽく、保護色として地面や水辺の環境に溶け込むような姿です。

生息地

コガモは湿地、湖沼、浅い川、干潟などで繁殖し、冬は暖かい地域へ移動します。特に日本では、冬の渡り鳥として見られることが多く、春と秋の渡りの時期に湿地や河川の中に群れを作っているのを目にすることがあります。

食性

コガモは水辺で水生植物の種子、葉、根、昆虫や甲殻類を食べます。水面でくちばしを使って水草をついばんだり、潜水して小動物を捕まえたりします。

渡り

コガモは渡り鳥で、北方の繁殖地（特に北ヨーロッパや中央アジア）から南方の温暖な地域（日本、中国、インドなど）に移動します。日本には冬に渡来し、春になると北方に戻ります。

保護状況

現在、コガモはIUCN（国際自然保護連合）によって「低危険（Least Concern）」に分類されており、全体的な個体数は安定しています。しかし、湿地の埋め立てや環境汚染などが影響を及ぼす可能性があるため、今後も生息地の保護が重要です。

コガモは、特に秋から春にかけての季節に日本の湿地で見ることができる美しい鳥で、その姿を観察することは多くのバードウォッチャーにとって楽しみのひとつです。