The dreaded chupacabra, or "goat-sucker"—named for its purported vampirism and appetite for livestock—first appeared in 1995 in Puerto Rico, just after the Hollywood movie Species opened on the island.

Since that time, the beast has jumped to the mainland, and is regularly "seen" and blamed for livestock predation in Central America, Mexico, Texas, Arizona and New Mexico. It is especially popular in Texas these days, where what was originally described as bipedal—something like a humanoid space alien—has morphed into a canine-like creature.

The chupacabra has become, in a surprisingly short time, a superstar of cryptozoology, recognized worldwide alongside Bigfoot and the Loch Ness Monster as evidence that we have yet to completely demystify nature, and that devils and demons really do lurk in the darkness.

Then along came Benjamin Radford, managing editor of Skeptical Inquirer magazine, to spoil all of the fun.

"To believe that the chupacabra exists is to believe that tens of thousands of large, bipedal unknown bloodsucking beasts with characteristics of a dozen different animals suddenly and mysteriously appeared in 1995 Puerto Rico, and have been attacking livestock in a dozen different countries for the past 15 years, without leaving a single dead body, bone or tooth, or even a single credible footprint," Radford writes in his new book, Tracking the Chupacabra, out from the University of New Mexico Press.

As Radford shows in this fascinating study of the madness of crowds, and how folklore rises and spreads, none of the 10 or so most famous chupacabra sightings holds up under the weight of rudimentary logic and science. Radford is even able to convincingly show that the first and most important chupacabra sighting, by Madelyne Tolentino in Puerto Rico in 1995, was the result of her having recently seen the aforementioned movie Species, whose creature Sil (created by artist H.R. Giger) bears a striking resemblance to the chupacabra as it was originally described.

Subsequent predations by and sightings of the mythical beast are found to be the result of widespread ignorance about the way dogs and coyotes kill livestock, the inevitable overzealousness of the media, and the well-known credulity of humans in general.

Radford's most interesting revelations are about the psychological and sociopolitical structures behind the folklore, especially as they relate to the monster's origins in Puerto Rico, where some people believe that the chupacabra is a secret U.S. government experiment gone wrong.

"Resentment, distrust and suspicion of the government are deeply embedded in Puerto Rican culture," he writes. "Puerto Rico exists in some ways as the neglected child of the United States, not important enough to be its own state, yet apparently critical to the U.S. military for its war games and live fire exercises, especially on the island of Vieques—a sore point with thousands of locals who endured months of disruptive and potentially dangerous nearby artillery bombardments."

It makes a kind of sense that islanders would create a beast—one that literally sucks the life out of the rural livestock economy—as a representative for their absent colonial master, Radford argues. It is also telling, he contends, that the chupacabra has only appeared in countries and states with large Hispanic populations—including Spain.

Currently, Texas is the creature's favorite haunt. A few years ago, after finding what turned out to be a dead coyote stricken with mange on her South Texas ranch, Phylis Canion cashed in on the publicity and became the "Chupacabra Lady," reportedly selling some $8,000 a month in T-shirts and souvenirs through her website.

Radford believes that all of the Texas chupacabra sightings are mangy coyotes or stray dogs, and he makes a solid case for this view. It's not exactly clear how the chupacabra changed from being an upright-walking monster with human-like hands and a face somewhat like the famous big-eyed aliens that abduct us from time to time, into the canine-style creature that is believed by some to stalk the Lone Star state. This is the nature of folklore, it seems. It adapts to its surroundings.

While Radford's book—which is well-written and a fun read—should be the last word on the chupacabra's real-world existence, it won't be. As the author points out, the beast has entered the realm of conspiracy, where no amount of evidence, or logic, can sway the true believer.