Bernd Heinrich's book, "One Man's Owl" has an interesting
discussion about eyespots, in which he mentions (1) hats worn
by joggers in Central Park, NY to ward off crows which harass
those who get too close to nests (2) the interactions between
an owl and two crows he had raised from infancy -- no
attacks or dives were ever made by either side of this
not-so-friendly group while being watched by the other; all
attacks were made while the head of the other was turned.