The skies of Bushwick have been emptier since a massive fire, a week ago, killed 500 trained pigeons trapped on the roof of a DeKalb Avenue building. But racing pigeons still fly over the neighborhood. On a recent afternoon, a flock of the beautiful, multi-colored birds passed over one of the buildings that lines the eastern side of Maria Hernandez Park. Some were bright white with brown wings, others black with grey specks; some had small short beaks, or feather “crowns” on top of their heads. These were no rats with wings.