This is the 7839th most frequent Japanese word.
唄い
"唄い" (utai) means "singing" or "chanting."
Here, 『唄い声』 refers to the sound or voice of singing, emphasizing the musical quality.
彼は美しい唄い声で歌った。
He sang with a beautiful voice.
In this context, 『唄い』 is used to describe the act or sound of singing as produced by the bird.
その鳥の唄いは森の中で響き渡った。
The bird's singing echoed throughout the forest.
Here, 『唄い』 refers to songs or tunes from the past, treating it as a noun.