In the article they mentioned
I was kind of curious about what happens to white doves after they're released since I've never seen a white bird out in the wild. There's a good reason why.
"A ribbon-cutting ceremony held near the building's front entrance concluded with the release of white doves."
From Slate.com: When Doves Fly Away
What happens to the doves after they fly away?
It depends on what kind of birds they are and how they're raised. Newspaper accounts don't identify the species released in Hiroshima, but white "peace" doves--the kind pictured in Picasso's famous poster--fare very badly in the wild. After centuries of domestic breeding, the white ring-neck dove is ill-equipped for urban survival. Bird rescue workers say that a ring-neck dove released in a city will likely starve--if it doesn't get hit by a car or eaten by another bird first.