白頭鷲とイヌワシ Bald Eagle And Golden Eagle


どうやって見分けますか? How do you identify which is which?

白頭鷲の大人は誰でもわかりますよね。I assume you can tell easily that this bird is a Bald Eagle.

こちらは犬鷲の大人。違いははっきりしてますね。This is a Golden Eagle. They look very different.

ただ、巣立ってから完全に成長するまでの5年間、この鳥たちは姿を変えていきます。クチバシと羽の色が変わっていくので、遠い上空を飛んでいる鳥を見ても、はっきりと見分けられない時の方が多いかもしれません。The problem is that they transform their appearance until fully grown for about five years after they fledge. So, many people can’t identify what they are for sure when they are flying up high in the sky.

白頭鷲の幼鳥。This is a juvenile Bald Eagle.

イヌワシの幼鳥の写真は残念ながらありません。その代わり、こちらのリンクをご覧ください。両者を比較しています。 Unfortunately, I didn’t find even one juvenile Golden Eagle on this trip. So, I found this site instead, a very useful website comparing both juvenile birds.

白頭鷲の幼鳥は成長するにつれて徐々に頭が白くなります。また、嘴も黒から黄色に変わっていきます。The head of juvenile Bald Eagles changes from dark brown to white gradually. The beak also changes from dark to yellow.

方や、イヌワシの変化は羽を広げた時の白い部分が少しずつなくなっていくことと、嘴の根本部分の鮮やかな黄色が徐々に焦茶色になる。つまり、脚をのぞいて全体が焦茶色になっていくことだと理解しています。On the other hand, the juvenile Golden Eagle has some white patches on their wings that will go away. The base of the beak is yellow but will become dark brown later. In fact, their entire body will become dark except for their feet.

こんな風に比較しても識別はまだまだ難しい。写真を撮ってズームアップしてみないとわからない。例えばこんな写真、どっちだかわかりますか?ヒントは、尻尾の羽の色と、胸のまだら色、それに嘴です。Although I summarized the comparison, it is still very difficult to identify them until you capture them and zoom in close. For example, refer to the picture below. Which bird is this? The hint is tail and chest, and beak.

答えは、白頭鷲の幼鳥です。羽を大きく広げてもらえるとわかりやすいですね。The answer is a juvenile Bald Eagle. It’s so much easier to identify it when it spreads its wings.

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