Radak: After saying that tall trees are the habitat for birds, it says that also tall mountains are habitat for wild animals. Nothing is useless; everything has a purpose, and all is for the benefit of man, who is supreme over all [creations].

Rashi: Hashem created them for Ye'elim. Radak - they seek tall mountains and dwell there. They are called "Ya'alei Sala" (Iyov 39:1).

Malbim: Tall places are a refuge from [predatory] animals that tear.

Rashi: It is shade and a hiding place from floods and rain.

Radak: There are caves and cavities in which Shefanim take refuge. They also take refuge under protrusions of rocks.

Malbim: They are weak, and need a refuge. Hashem designated rocks for their abode. Wondrous Hashgachah designated for each being its abode and place with the ultimate good!