John Gill Commentary Isaiah 18:6

"They shall be left together unto the ravenous birds of the mountains, and to the beasts of the earth; and the ravenous birds shall summer upon them, and all the beasts of the earth shall winter upon them." — Isaiah 18:6 (ASV)

They shall be left, together unto the fowls of the mountains,
and to the beasts of the earth
That is, both sprigs and branches; with the fruit of them, which being unripe, are disregarded by men, but fed upon by birds and beasts; the fruits by the former, and the tender sprigs and green branches by the latter; signifying the destruction of the Ethiopians or Egyptians, and that the princes and the people should fall together, and lie unburied, and become a prey to birds and beasts; or the destruction of the Assyrian army slain by the angel, as Aben Ezra and others; though some interpret it of the army of Gog and Magog, as before observed; see (Ezekiel 39:17–20) (Revelation 19:17Revelation 19:18) : and the fowls shall summer upon them, and all the beasts of the
earth shall winter upon them ;
not that the one should feed upon them in the summer time, and the other in the winter; the fowls in the summer time, when they fly in large flocks, and the beasts in the winter, when they go together in great numbers, as Kimchi; but the sense is, that the carnage should be so great, there would be sufficient for them both, all the year long.