why do you think wordsworth has chosen the song of the nightingale and the cuckoo forcamprison with the solitary reaper song

Usually melodious tunes or voices are compared to that of a cuckoo's or a nightingale's. Therefore, to highlight the fact that the solitary reaper sung more melodiously than even the most melodious birds known, the poet uses the comparison of both the birds. This shows how much the poet was touched by the song of the reaper. Please go through the summary to understand the imageries used in the poem. The summary is available at our website.