The book is a research project documenting a bunch of weird stories originating in the San Luis Valley (SLV). SLV is in the Sangre de Christo mountains of northern New Mexico, and was featured in a book titled Weird America. Among the weird happenings said to have happened in SLV are UFO sightings and "Unexplained Animal Death" (UAD).
The UAD phenemona is where animals, livestock generally, are found mutilated in a bizarre fashion. The first of the unexplainable animal mutilations happened in SLV, in 1967, when an Appaloosa horse was found stripped of its skin and flesh from its shoulders to its nose, etc.
This book is highly recommended if you like stories of strange and odd occurrences.