also: みそさざい
noun
Eurasian wren; wren
A small brown songbird (Troglodytes troglodytes) found across Eurasia. In everyday Japanese, the katakana name is standard.
ミソサザイは小さくて丸い鳥だ。
The Eurasian wren is a small, round bird.
森でミソサザイのさえずりを聞いた。
I heard a wren singing in the forest.
Rare kanji form; the characters are obscure and not in common use.
Ateji spelling; the kanji 三十三才 literally mean 'thirty-three years old' and are used phonetically for the bird's name.
The Japanese name ミソサザイ is of uncertain origin. The kanji 鷦鷯 are Chinese characters for the wren, while 三十三才 is an ateji spelling based on the reading.