The San Diego Chargers placed rookie linebacker Bront Bird on injured reserve on Tuesday, a league source confirmed on Tuesday.
Bird injured his knee during Saturday's 38-10 loss to the Detroit Lions.
Signed as an undrafted free agent out of Texas Tech, Bird opened the 2011 season on the Chargers' practice squad. Activated in November, Bird had 14 tackles and a pass defensed in nine games this season.
The Chargers have not yet filled Bird's spot on the 53-man roster.