What kind of nest is this?
Rashi: It is a nest of Hefker birds.
What is the comparison to finding a nest?
Radak: The nest is Hefker and abandoned to anyone who passes. This is like "ch'Of Noded Ken Meshulach" (16:2). So the army of nations, I overcame it, and no one could stand against me. The Lamed in "l'Cheil" us extra, like the Lamed in "Hargu l'Avner" (Shmuel II, 3:30).
Malbim: A tyrant who conquers kingdoms, he plunders their storehouses only after many wars. Meanwhile, the country waxed poor and they hid the storehouses, so he finds a poor, empty nation. I found the wealth of nations like a nest in which the mother sits on the chicks. I conquered it suddenly, when they were calm, and their wealth was like a bird on its nest.
What is the comparison to gathering abandoned eggs?
Rashi: It is like a man who gathers eggs that their mother abandoned them, and no one protests against him to protect them.
Radak, Malbim: When a mother bird is on her eggs, and one comes to take them, it flaps its wings and strikes the nest to stop him, if it can. When the eggs are abandoned, there is no impediment. So no one prevented me from what I took and gathered, not even verbally, and all the more so in deed.
Why does it say "Noded Kanaf u'Fotzeh Feh u'Metzaftzef"?
Rashi: All of these expressions apply to birds. Because he depicted the exiles like a nest of birds and abandoned eggs, he uses the expression that the father and mother did not chirp over them.
Radak: Because he depicted the army of nations as a nest and abandoned eggs, he depicts the nations as a bird. Noded is Po'el Yotzei (it acts on others). Or, it is Po'el Omed (the action applies only to the subject), like the other verbs (Potzeh and Metzaftzef). This is like "Noveles Aleha" (1:30) - because the leaves wither, the tree is called Noveles. Similarly, [the bird is called] "Noded Kanaf" due to its wings, which it flaps.
Malbim: A bird fights with its wings against one who comes to take its chicks. If its feathers fell off, it bites with its mouth, or at least chirps (raise the voice) against him. Even though I came against countries that were serene and strong, no one protested against me. I took their wealth easily without war. This shows his great Gevurah!