Due to limited access to the text online, the exact answer to your question cannot be found; however, it can be noted that N. Scott Momaday certainly uses animals as a very prominent recurring motif in his novel The Ancient Child, and looking at those recurring references to animals may help you find your answer.
Grey, one of the novel's protagonists, is particularly associated with animals. At the opening of the story, she is at the bedside of her dying grandmother, day dreaming about a relationship with Billy the Kid. Momaday also describes Grey as coming to realize she is a medicine woman with healing powers. It is specifically her dreams that help her realize her healing powers. In her dreams, both the "animals and dead talk to" Grey (p. 173, as cited in Tudor, "N. Scott Momaday's The Ancient Child And the American-Dime Novel"). What's more, the author states:
In her dreams the earth, eagles, fishes, coyotes, tortoises, mice and spiders instruct her. (p. 173, as cited in Tudor, "N. Scott Momaday's The Ancient Child And the American-Dime Novel")
Since she is described as having such a close relationship with animals and since this relationship closely ties in with her healing abilities, it is most likely Grey who feels comfort from knowing that animals have made their homes under her house. What's more, Grey is described as living in an adobe house, making it much more likely for her home to be a home to animals. Therefore, if you continue skimming through your text in search of references to Grey and animals, especially references to animals, you will most likely find your answer.