The book is written for young readers, and so has a simple style intended to be easily understood. Instead of using Realism or Naturalism in describing the wolves and nature, the author uses human-like descriptions to show their movements and how the protagonist ascribes her own emotions to their states.
Miyax stared hard at the regal black wolf, hoping to catch his eye. She must somehow tell him that she was starving and ask him for food.
(George, Julie of the Wolves, Google Books)
The tone of the story is therefore easy to read while retaining a sense of wonder and suspense; the protagonist, Miyax, is young and not fully aware of either her own emotions or of the instinct -- versus reason -- of the wolves. She is amazed that they tolerate her, while still yearning for her family life with other human beings. As the novel progresses, the reader sees the world through Miyax's eyes, and understands how her outlook shapes her experiences, even as those experiences shape her in turn.