In the meantime here is what hawk expert and the designer of the nest nook, John Blakeman has to say--
Attached is a design for a $10 landing pole attachment that will work for both Nest Nook designs, for the one on the wall, and the one attached to a ledge. It's two automotive hose clamps and 3-ft piece of treated 2x2 wood.
Sorry, John. I'm hoping to get the information soon, and when I do I'll whip it your way asap.