Kirk (calf) worked out on the side at Monday's practice, Matt Barrows of The Athletic reports.
With Ricky Pearsall (knee, IR) out for the season, the 49ers also were without Mike Evans (quadriceps) and rookie second-round pick De'Zhaun Stribling (hamstring) on Monday, though both Stribling and Kirk appeared to be operating at at least three-quarters speed. Kirk now has missed a week of practice, but his activity level to begin this week indicates he's likely to mix back into drills in the near future.