The first known reference to the onza is in a wonderful book written in 1795 by an ex-Jesuit missionary named Ignatz Pfefferkorn. Published in 1949 as Sonora: A Description of the Province and reprinted by the University of Arizona Press, it’s a great starting place for learning about our region.
While much has changed, a surprising number of his descriptions and comments still ring true today. In his book, Pfefferkorn tells us in considerable detail of the three large cats to be found in Sonora: the tigre (jaguar), the león (puma), and the onza. This last beast of prey is a little thinner and lighter in color than the puma, but much fiercer.
If you start a conversation nowadays with Sonorans about big cats in the sierra, chances are you will hear the same thing: there are tigres, leones, and onzas, and the onza is like a leon only a bit lighter in build and much more aggressive.
There is only one problem: few “onzas” have been killed and preserved for study, and all specimens seem to fall into the range to be expected of female mountain lions in the tropics. In other words, the only evidence for the existence of these elusive cats is anecdotal. That hasn’t stopped a lot of folks from telling onza stories, both in print and around the campfire.
Here in brief is the story of C.B. Ruggles’ 1926 encounter with an Onza in the mountains of eastern Sonora. Ruggles, with two friends and his airdale dog, were searching for a lost mine. During the night they heard strange noises near their camp. In the morning they found the dog missing and 5” cat tracks on the ground. They found the remains of the dog and set their traps nearby. What they caught was a large fierce cat, described as long of tail and body and dark in color, with a large head. Some Indians identified the carcass as that of an onza. The hunters took some fuzzy photographs that show a dead animal that looks like a mountain lion.
The famous lion-hunting Lee brothers of Arizona claim to have bagged an onza in the west coast state of Nayarit, Mexico. J. Frank Dobie tells of an onza experience (in fact, this one was a were-onza), and in 1961, Robert Marshall wrote a whole book on the subject.
The most recent onza book is ONZA! The Hunt for a Legendary Cat, by Neil B. Carmony (1995: High Lonesome Books), my source for this blog. This excellent compendium of all available onza lore and information comes to the conclusion that there is no real evidence that the onza exists. That, however doesn’t stop the believers, the seekers, and the Sonoran storytellers.