She dwelleth and abideth on the rock - "He rarely quits the mountains to descend into the plains. Each pair live in an insulated state, establishing their quarters on some high and precipitous cliff, at a respectful distance from others of the same species." "Edin. Ency." They seem to occupy the same cliff, or place of abode, during their lives; and hence, it is that they are represented as having a permanent abode on the lofty rock. In Damir it is said that the blind poet Besar, son of Jazidi, being asked, if God would give him the choice to be an animal, what he would be, said that he would wish to be nothing else than an "alokab," a species of the eagle, for they dwelt in places to which no wild animal could have access. Scheutzer, "Phys. Sac. in loc." The word rendered "abideth" means commonly "to pass the night," and here refers to the fact that the high rock was its constant abode or dwelling. By night as well as by day, the eagle had his home there.
Upon the crag of the rock - Hebrew, "Upon the tooth of the rock" - from the resemblance of the crag of a rock to a tooth.

Upon the crag of the rock - שן סלע shen sela, the tooth of the rock, i.e., some projecting part, whither adventurous man himself dares not follow her.
And the strong place - ומצודה umetsudah. Mr. Good translates this word ravine, and joins it to Job 39:29, thus: "And thence espieth the ravine: her eyes trace the prey afar off."

She dwelleth and abideth on the rock, upon the crag of the rock, and the strong place. Where she and her young are safe: so Pliny (r) says, eagles make their nests in rocks, even in the precipices of them, as the philosopher quoted in the preceding verse; and here on the tooth, edge, or precipice of the rock, which is inaccessible, and so like a strong fortified place.
(r) Nat. Hist. l. 10. 3.

abideth--securely (Psalm 91:1); it occupies the same abode mostly for life.
crag--literally, "tooth" (1-Samuel 14:5, Margin).
strong place--citadel, fastness.