Rashi: When summer is approaching, trees produce flowers, and travelers enjoy seeing them.

Rashi (13, from Shir ha'Shirim Rabah 2:25): They are Moshe and Aharon, who were prepared for all your needs ¹ .

Malbim (Melitzah): Also the Divine seeds planted in the Nefesh, when Ru'ach takes effect on them (when the Nefesh was sleeping during its winter, they were only in potential) to be actualized and revealed, and seen in the land.

Rashi: It is when birds sing (Malbim (Mashal) - in summer). They give a nice sound for travelers.

Rashi (13, from Shir ha'Shirim Rabah 2:25): The time to sing Shiras ha'Yam.

Malbim (Melitzah): The Divine Nefesh has two levels. (a) The Neshamah in the body - it does not separate from it for a moment. (b) Refer to 2:12:3:5. The first level is like a chirping bird. It does not sing in winter. Even so, it does not distance from its land. Rather, it dwells like a dove, in "Evrei Fi Fachas" (Yirmeyah 48:28) and "b'Chagvei ha'Sela" (below, 14). When the Nefesh sleeps and the intellect dwells in the body, it is silent and does not sing. Now that the Nefesh woke, it is time to sing Shir Hashem and be elevated with pleasant songs of Nevu'ah and understanding - the Nefesh's song.

Rashi: This is like Torim (turtledoves) and Bnei Yonah. They sing and chirp in Nisan.

Rashi (13, from Shir ha'Shirim Rabah 2:25): This is [the voice of] Moshe, the good Tayar ¹ .

Rashi (13, according to the metaphor): It is the voice that the time ² came for you to leave Egypt.

Seforno: It is like a mourning voice. "It was heard in our land" - "Namogu Kol Yoshevei Kena'an" (Shemos 15:15).

Malbim: A higher level of the Divine Nefesh is called Chayah and Yechidah. It comes to him from above, according to his deeds and Kedushah. It separates from him when the Nefesh sleeps during its winter. 'If it merits more, they give to it a Neshamah