The Nationals optioned Bird to Triple-A Rochester following Tuesday's game against the Rockies.
Bird pitched a scoreless inning Tuesday, bringing his ERA down to 5.35 through 38.2 innings on the season, but the Nationals will send him down to Rochester in preparation for Luis Perales' arrival to the majors Wednesday. Bird could still return to Washington later in the year to provide the parent club with a fresh arm, but he likely would be limited to middle-relief duty.