Birdsong (5-6) allowed three runs on four hits and three walks over 4.1 innings Sunday, striking out 11 and taking a loss against St. Louis.
Birdsong did not factor into the decision in a loss to the Brewers on Thursday, allowing two hits and one walk over five scoreless innings while striking out four.
Birdsong (3-5) was charged with the loss against Arizona on Wednesday, allowing two runs on three hits and five walks over three innings while striking out four.
Birdsong (3-4) allowed five runs on four hits and four walks while striking out six over 3.2 innings to take the loss versus the Brewers on Thursday.
The Giants recalled Birdsong from Triple-A Sacramento on Tuesday, Shayna Rubin of the San Francisco Chronicle reports.
Birdsong will rejoin the Giants' rotation in the coming days, Alex Pavlovic of NBC Sports Bay Area reports.
The Giants optioned Birdsong to Single-A San Jose on Sunday.
Birdsong (3-0) picked up the win over the Rockies on Saturday, allowing three hits and three walks over five shutout innings while striking out eight.
Birdsong has been appointed the Giants' 27th man for Saturday's doubleheader against the Rockies. He'll start Game 2.
Birdsong has been confirmed as the starter for the second game of Saturday's doubleheader against the Rockies, Alex Pavlovic of NBC Sports Bay Area reports.