What is known as mother-croon of bird? Why is the song sung in hushed voice?

• “Mother-croon of bird” is the gentle humming voice of a mother-bird to its baby.
• The song is not sung in a hushed voice, but it is heard in the hushed moments of twilight, as then the noises in the surroundings gets reduced.

To explain the lines —

For song and mother-croon of bird,
In hushed and happy twilight heard —

The poet says that the song and mother-croon of the birds living on the tree are heard in the quiet evening hours. That makes the twilight hours happy for the man who hears the song.

• A-1 Mother croon of the bird is the gentle humming voice of a mother bird for her baby or her young ones.
• A-2 The song sung by the mother 🐦 bird for her baby or young ones is heard in the hushed hours.
• In the above lines the poet says that the mother 🐦 bird sings a song for her young ones in a sweet and gentle voice, thus making the whole universe a heaven.

• Song sung in silence and calm