How does Tony regard the owl that Ultima brings with her?
In Chapter One, Tony regards Ultima's owl as a special presence that has been sent to watch over the family.
Even though owls are said to portend evil, Tony feels that Ultima's owl will be different. He deeply believes that this very special owl which sits in a juniper tree outside Ultima's window will not be a bruja or a witch. When Tony's father makes no move to shoot the owl, Tony is further reassured about his assessment of Ultima's owl.
So it is that when he sleeps on the first night of Ultima's stay, Tony dreams wonderful dreams about the owl. In his dream, he sees the owl as a good and protective presence. The owl takes both the Virgin of Guadalupe (the patron saint of the town) and the babies in Limbo to heaven.
In Roman Catholic theology, The Limbo of Infants is a theory about the fate of unbaptized babies. Accordingly, when babies die without the benefit of baptismal dispensation for original sin, they can theoretically end up in a state of Limbo. In Tony's dream, he sees Ultima's owl bringing all the infants in Limbo to heaven. Ultima's owl is a benign, rather than an oppressive or virulent, presence.