Grass Whistle

Grass Whistles are objects in. They are plants that grow in many places in Hyrule. With them, Link can whistle tunes to summon either a hawk or Epona. As Wolf Link, Link can howl the appropriate tune when he is near either type of Grass Whistle.

Hawk Grass
Link can blow into Hawk Grass in order to summon a hawk, which can be aimed and released to retrieve faraway objects or attack enemies. If Link calls a hawk as a wolf, it points out secrets in the area, such as in the Sacred Grove where Link fights the Skull Kid.

At the beginning of Link's quest, it is necessary to use a Hawk Grass to get Uli's cradle back from a monkey. Near Lake Hylia, when Lanayru Province is covered by Twilight, Wolf Link must fight and tame a Twilit Kargarok called upon by Hawk Grass, which he can use to call it again anytime. Link can ride the Twilit Kargarok to access upper Zora's River. After the Twilight is lifted, a Kargarok is required to play Plumm's minigame, which he can only do as a wolf.

Horse Grass
Horse Grass is shaped like a horseshoe and can be used to call Epona. When whistled, the grass plays "Epona's Song." After monsters invade Ordon, Epona will not respond to the whistle for a portion of the story. The Horse Grass becomes usable again when Link wrangles her in Kakariko Village. For the majority of Link's quest, Horse Grass is the only way of summoning Epona. Later on, Link receives the Horse Call, which allows him to summon Epona without the need of a Horse Grass.