Nightravens

The Nightravens were monsters that attacked people in flocks, picking their bones clean, but they fled from light. In the city of Gisoreux, there needed be a torch outside every house, to be lit when the Nightravens came. However, the last flock was destroyed by Sir Thopas over five hundred years ago, so Gisoreux is full of torches that are never lit.

Source

 * Warhammer Fantasy RPG 2nd ED -- Knights of the Grail pg. 33