We heard a ground squirrel whistle down over the bluff among the dead treetops.
1. Many rodents will make a sort of whistling sound to communicate.
2. The listeners are below the bluff, and the squirrel is on top of the bluff.
We heard the ground squirrel whistle.
He was on top and we were below.
The sound travelled horizontally to the edge and then 'fell' down to our ears after going over the edge..