If I were the writer, I would be so much likely to write it as: In the summer, …in the autumn… However, after reading it, I have a feeling that “in autumn” is much better.
Is it because “In the summer” = in the season of summer wherein “roses”…, while “in autumn” = in autumn times wherein no particular “players” on the stage, or simply the asymmetricity is better here?
Oh, it’s a great help to me. The linkage of “the” to a succeeding of-phrase allows my nearsighted eye to see Alan’s birds fly south in a clearer and more convinced manner.