How does Hashem prepare food for animals?
Radak: Animals without food; Hashem prepares vegetation on mountains for them. Just like Hashem helps the weak who cannot help themselves, so He did to Yisrael who were abandoned in Galus without any strength. Hashem desires the weak and lowly, and not the powerful who pride themselves over their strength and ability.
Malbim: His Hashgachah encompasses also animals.
Why does it mention specifically children of ravens?
Rashi and Radak, from Eruvin 22a: It is cruel to its children. (It is black, and they are white.) Hashem has mercy on them, and prepares for them flies amidst their excrement; they enter into their mouths.
Do children of ravens truly call to Hashem?
Radak: They scream; it is as if; they call to Hashem for their prey.
Malbim: They 'announce' (publicize) that He "does not desire the horse's strength" (10; refer to 147:10:1:2, 147:10:2:3). I.e. attaining food does not require strength and efforts; it is from Hashem. He feeds the weak living beings like ravens' children. Anyone who hopes to Him finds his food in his house, without horses, chariots and war, like He provides for Bnei Orev.
