The whistle is used by Captains to call idle Pikmin to them. A small circle shows where the whistle will blow to. Holding the button down makes the circle grow larger. When used, the captain shoots a few sound waves that hit the circle and expand, while turning from red, to yellow, and eventually blue. In Pikmin 2 the Pluckaphone allows the captains to uproot pikmin using the whistle, and the Mega Tweeter allows for a wider range, and a longer lasting whistle. In Super Smash Bros. Brawl, the whistle is used to gather and sort Pikmin. It appears much the same as it does in the Pikmin series, but it is smaller, without a reticule, and lasts a shorter amount of time. In Pikmin 3, The Whistle has taken on a new look, and the range is much smaller.
In the Gamecube games the whistle cursor points in the same direction as the captain, but on the Wii versions you can move the cursor anywhere on the screen without moving Captain Olimar.