Fall out?
Peregrines do not "fall" out of their nests or evolution would have eaten them by now! So what about Taku you ask (2007 chick that died), Taku didn't "fall" from the nestbox on the Radisson, the necrosis of her brain finally was affecting her muscular control (she couldn't hold her head up) and her balance centre and it is believed would have died that day had she not pitched herself over the edge of the nestbox. Falling is an accident, pitching oneself over the edge due to a terminal cerebral accident, is not falling.
As for the front section of this nestbox, a horse would have difficulty getting over that to accidentally "fall"
And I like the design too Carly!