throwing out runner stealing second

Question
when a runner takes off from first to steal second, who should call it out to warn catcher and second/short stop?

Answer
hi patti
thanks for the question.

when a runner is staling 2nd base, the 1b should give a verbal that the runner is going.

however, the catcher is always aware that the runner is running as he peaks when the pitcher throws the pitch. the middle infielder that will receive the throw is also looking just after the pitcher commits to throwing home. without the catcher and middle infielder taking a quick look and anticipating the steal, it would not matter who was giving the verbal cue.

hope this helps.
steve