It is the imagination of the poet and the emotional migration of the poet. Birds are tired, so are people. The word "Tuo" is a further rendering of the scenery and a fantastic imagination. On the other hand, it also highlights the fatigue degree of birds, because Tuo is a load, which is carried by the sun. In this way, what you see is not only a kind of scenery, but also the poet's experience of life.
Extended data:
This poem adopts the popular poem style at that time from the overall framework. Small description, concise outline, prose sentence pattern and improvisation all show the style of Tagore and Japanese haiku. Liu Dabai pays attention to the combination of emotion and scenery in his description of nature. This is the so-called combination of poetry and painting, and the blending of scenes in old poems.
The whole poem is full of the emotional appeal of the old poem, with only a few strokes, that is, it outlines a beautiful picture with sound and emotion, and at the same time it has the poet's own style, just like the last two sentences, which personifies the reed through "makeup" and "beauty", adding a little interest and vitality to the whole poem.