Imagine you are a CIA spy.

Imagine you are a CIA spy.  You want to put a listening device outside an apartment window high above the street in a Soviet-era Eastern European capital.  How would you do it?

According to this story, the real CIA would have done it by hiding a tiny listening device in a small, nondescript, hollowed-out piece of slate, then used a trained raven to place it on the ledge outside that window.  It's probably hard for younger folks to even imagine a world where such a method would seem sane – but back then, quadricopters, actual working robots, drones, etc. were just science fiction fantasies.  The tiny listening device would have been a marvel all by itself (back then, just the microphone would have been the size of a soda bottle)...