There's something happening in the stables, although it isn't obvious to the average observer what it is. The creatures are restless, shifting within their respective pens, and some of the smaller creatures (the nifflers! the augureys!) are downright unsettled.

For those who have witnessed death firsthand, they might see wild thestrals (rather than the carefully groomed ones that belong to the school) packed into stalls where they don't belong. For those who can't see the thestrals, isn't it straaaaange how the creatures are all bunched up to one side in their stalls?