Adam Clarke on Psalms 104:18

The high hills are a refuge - The barren tops of the highest hills, and the craggy abrupt precipices of the most stupendous rocks, are not without their uses: they afford protection, refuge, and food, for creatures whose dispositions and habits are suited to such places; and thus no part of the creation is useless. The creatures who are their inhabitants are necessary links in the great chain of animated beings, and show the wisdom and providence of God.

For a description of the covey, see Lev 11:5. The יעל yael, translated here the wild goat, is no doubt a creature of the stag or deer kind; the ibex, chamois, antelope, etc.