What are the duties of the bowler's end umpire and the striker's end (square leg) umpire?

Bowler's end umpire

• Calls Play before the first ball and on resumption after any interval or interruption, and calls Time when the ball is dead at the start of any interval or interruption (Laws 12.1 and 12.2).
• Stands so as not to interfere with the bowler's run-up or the striker's view, while still seeing any act needing a decision (Law 2.9).
• Calls and signals No ball for the bowler's foot faults: Cricket Australia's technique guidelines list the front foot having no part grounded or raised behind the popping crease, or the back foot touching or outside the return crease. Keep your head still, focus on the striker, flick your eyes down to check the front foot, then back to the striker.
• Repeats signals to the scorers when the ball is dead and gives the final signal for Short run (Law 2.13).
• Moves after the ball is played to see the batters touching down at the popping crease at the bowler's end for possible run outs.

Striker's end umpire

• Under the technique guidelines is responsible for No balls for the wicket-keeper's position and all fielding restrictions (including more than 2 fielders behind the popping crease on the on side), and for stumped, hit wicket and run out at that end.
• Supports the bowler's end umpire on catches carrying, and on dangerous non-pitching and over-shoulder or head-high bounced deliveries.
• May elect to stand on the off side of the pitch instead of the on side, provided they inform the fielding captain, the striker and the other umpire (Law 2.9).

Both

• Umpires change ends after each side has had one completed innings (Law 2.10).
• If an umpire has to be replaced, the replacement acts only as striker's end umpire unless the captains agree they take full responsibility (Law 2.2).