The material below is Open Game Content from a 3PP Source
Trainer’s Whistle: This simple whistle often commemorates tasks in which the halfling finds ways to eliminate the threat posed by particular sorts of animals without actually killing them. A halfling can, when first gaining this keepsake, designate one specific kind of animal (bears, wolves, cats, and so on) for which she has a particular affinity. When she uses the keepsake while casting calm animals,she can affect her chosen animal kind plus one other kind of animal (instead of the spell’s normal limitation of affecting only one kind of animal). Alternatively, she can only affect her chosen kind of animal, and then adds her caster level to the number of HD of animals affected (this is in addition to the normal 2d4 + caster level worth of HD affected).