This whistle, made of rough hewn wood in the rough shape of a wolf's head, releases a high pitched cry when blown into, akin to a distressed song bird.

While attuned to this item, you may, as an action, blow into the whistle. When blown into, you may spend a relevant amount of uses of wild shape to summon one of any creature you can wild shape into of your choosing. It appears beside you, is friendly to you and your allies, obeys your commands telepathically with no action required, and shares its initiative score with you, going directly after you. 

This summon lasts until the summoned creature hits 0 hit points, or until the end of your next long rest, after which it will disappear from whence it came.

Notes: Druid, Summoning