 The invunche is fed solely by warlocks and is only allowed to search for its own edibles if food is lacking inside the cave.Jose Donoso's magical realist book "The Obscene Bird of Night" reinterprets invunche folklore as a way to bind a male child in a sack to prevent escape and bodily growth.Travel writer Bruce Chatwin gives an account of Chilote witchcraft and the invunche in his book "In Patagonia".