"Into That Forest" by Louis Nowra is set in 1920/30s Tasmania, at a time when bounties on tiger hides were slowly causing the destruction of that species. Narrated by an elderly Hannah, the book has a strong sense of place and character, but it is the assimilation of Hannah and Becky into tiger culture (and their departure from human social "norms") that is incredibly fascinating. Hannah and Becky are two very different little girls; while Becky yearns for home and her father and doesn't want to lose her language or clothing, even memorizing the colors of the rainbow and counting as high as she can, Hannah adapts quickly, mimicking the tigers' vocalizations and body postures and pushing away thoughts of her parents' probable deaths.
Ultimately, in order to survive, both girls learn to hunt, eat and live with the tigers, becoming very nearly tigers themselves in the four years they spend in the wilderness.
Of course, they are eventually discovered, and their forced reintegration into human culture has inevitably tragic consequences.
Filled with thrilling moments and brilliant descriptions, "Into That Forest" could be just another tale of orphaned children growing up with animals--see the Jungle Book or the eastern European "wild" children raised by packs of dogs or any number of such tales--but it is so much more. There is a meditational quality, as there must be, not just on what it means to be human or animal, but also on our impact on species. The last Tasmanian tiger died in captivity in 1936.
Despite being a fairly fast read, do not underestimate the book's emotional punch. Keep tissue handy.
As a side note, some readers find Hannah's dialect to be off-putting. I thought it was easy to understand, and enriched to the narrative.