Luke 17:37b, ὅπου τὸ σῶμα ἐκεῖ καὶ οἱ ἀετοὶ ἐπισυναχθήσονται (“wheresoever the body is, thither will the eagles be gathered together”; KJV), is certainly one of the most enigmatic of Jesus’ sayings. Commentators have noted that Jesus employed a proverbial saying to reply to his disciples’ question, “Where, Lord?” (Luke 17:37a); however, they differ on what the proverb means in this context. Some understand it to mean that the Son of Man will inevitably appear just as eagles inevitably show up where there is carrion. Others suggest that it refers to the swiftness with which the Son of Man will come in judgment. Still others take it to mean that the Son of Man will come when the world has become like a lifeless corpse, rotten with evil and ripe for judgment. None of these interpretations seems satisfactory in light of the disciples terse question: “Where, Lord?”
From my experience, the most effective way to understand a saying of Jesus preserved in the Synoptic Gospels, i.e., Matthew, Mark and Luke, is to translate it into Hebrew and then ask what the resultant Hebrew means. When the saying about a dead body and eagles is put into Hebrew, one notices a possible allusion to a passage from the book of Job that describes the habits of vultures:
It [the vulture] dwells among the rocks and there it lodges; its station is a crevice in the rock; from there it searches for food, keenly scanning the distance, that its brood may be gorged with blood; and where the slain are, there the vulture is. (Job 39:28-30, New English Bible)
This passage concludes with the proverb to which Jesus seems to be alluding: וּבַאֲשֶׁר חֲלָלִים שָׁם הוּא (uva’asher khalalim sham hu, and wherever there are slain, there it [the vulture] is), that is, whenever the slain lie exposed in the open field, immediately vultures appear and huddle around them.
Many English versions of the Bible, for example, the King James Version, present the reader with four Hebraisms in their translations of the eight Greek words in Luke 17:37b:
-  Matthew’s parallel is: ὅπου ἐὰν ᾖ τὸ πτῶμα ἐκεῖ συναχθήσονται οἱ ἀετοί (wherever there may be the corpse, there will be gathered the eagles; Matt 24:28) ↩