Because of the mountain of Zion, which is desolate
Meaning either the city of Jerusalem in general, or the temple in particular, which both lay in ruins: but the latter gave the truly godly the greatest concern; that the seat of divine Majesty should be in such a condition; that the public exercises of religion should cease, and there be no more opportunities of waiting upon God, and worshipping him as heretofore; their civil interest, and the loss of that did not so much affect them as the interest of religion, and what that suffered: the foxes walk upon it:
as they do in desolate places, shunning the company of men; but here they walked in common, and as freely as in the woods and deserts: this was fulfilled in the destruction of the second temple, as well as the first. R. Akiba F3 and his companions were walking together; they saw a fox come out of the holy of holies; they wept, but he laughed or rejoiced; they wept, that in the place where the stranger that drew near should die, now foxes walked upon it; he laughed or rejoiced, because, as this prophecy was fulfilled, so would others that predicted good things.
The Brenton translation of the Septuagint is in the public domain.