From where does the bird wander?
Rashi: From its nest.
What is the comparison to "Ken Meshulach"?
Rashi: Just like chicks sent from their nest are dislocated, so will be Bnos Mo'av to the passages of Arnon.
Radak: They have no place to rest.
Malbim: Bnei Mo'av will not wait for the Shali'ach to return. Once the Shali'ach goes 1 , the villages and cities will go via the passages of Arnon to flee to Eretz Yisrael. There will not be time to wait for the Shali'ach to return, for the enemy will come quickly. Also, they need not fear lest Bnei Yehudah not accept them (refer to 16:5:1:4). If they take a nest from a bird, it is forced to roam. In the Nimshal, had the enemy conquered the land first, via this the people would need to roam. Here, He commands them to flee by themselves and abandon the country before the enemy comes. This is like a bird that chooses to leave its nest. First is wanders, and then its nest is sent, and automatically it becomes Hefker.
Malbim (1) said that Mo'av are haughty, and they will not request from Yehudah to save them! This requires investigation. (PF)
What are "Bnos Mo'av"?
Radak: They are the villages, like "b'Cheshbon uv'Chol Benoseha" (Bamidbar 21:25). They will take them all to Arnon and send them to exile.
What is the significance of Arnon?
Radak: It is the border of Mo'av. Malbim - it is close to Eretz Yisrael.
