I grew up in Connecticut, where mourning doves were common. To my mind, it's one of the most beautiful birds in that area, with a call surpassed in loneliness only by owls. I've long associated the Mourning Dove with the goddess Aphrodite, and of course Quimbanda's Pomba Gira.
Peace, in the human world usually comes only after terrible conflict - after everyone involved grows sick of violence and death. The mourning dove is the herald of peace - a beautiful sentient bird with a call that sounds as if sprung from the memory of great loss.