The destruction that had for so long spared them had finally begun to reach their nests; they lost scouts every day, simply trying to discover the extent of the destruction that was plaguing the Underdark. The death of so many brothers and sisters told them plenty, it not in detail.
Even their hated rivals, the Dark Elves, were feeling the strain of the demonic force. If so many lives and so much of their home was under attack now, there was only one way to go. They had heard the whispers from the Drow that the surface was desolate and abandoned, ripe for the picking. They could thrive there, easily, and start anew.
The organized exodus they had planned was disturbed as the turmoil finally reached their front door. It was in a swarm that they fled, everyone for themselves, protecting the things they could not do without as they reached the surface in a chittering mass of claws, teeth, and glittering eyes. Had they lost some more brothers and sisters in the frenzy? It didn’t matter. All was not lost. They would persist, and fight tooth and nail to claim and defend their new home.