夏なつ羽ばね

noun

summer plumage; nuptial plumage

Ornithological term for the breeding-season plumage of birds, often brighter or more colorful than winter plumage.

• 夏なつ羽ばねになると、オスの羽はね色いろが鮮あざやかになる。

  When they get their summer plumage, the males' feather colors become vivid.

• この鳥とりの夏なつ羽ばねは、頭とう部ぶが黒くろくなるのが特とく徴ちょうです。

  A characteristic of this bird's nuptial plumage is that its head turns black.