(Photo by George Andrejko - Arizona Game and Fish Department)

The (former) Hualapai Mexican vole.

The U.S. Fish and Wildlife Service has removed the Hualapai Mexican vole (Microtus mexicanus hualpaiensis) from the Federal List of Endangered and Threatened Wildlife because genetic research shows that it’s not a separate subspecies.

Jim deVos of the Arizona Game and Fish Department said such corrections sometimes become necessary as new methods update old taxonomy, which often relied on meager data.

“Early taxonomy said that it was distinct. But, as we’ve looked underneath, the genetics of the issue find that it’s far more widespread and common than was originally thought," he said.

Edward A. Goldman established the subspecies in 1938, based on four specimens collected in the Hualapai Mountains near Kingman. In 1987, the USFWS listed it as endangered, motivated in part by concerns over degradation — caused by drought, grazing, road construction, mining and erosion — in its federally recognized habitat.

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“But a lot of folks thought, ‘Well, but you know what? There are other populations that look very, very similar.’ So that led to some genetic studies that, in fact, demonstrated it was not unique to the Hualapai Mountains, and in fact occurred in several mountain ranges in Northwestern Arizona and one into Utah,” deVos said.

The ruling lumps the 4- to 6-inch, brown-and-black rodent back into the broader group known as Mexican voles (Microtus mexicanus), an International Union for Conservation of Nature "species of least concern" found across the southern Rocky Mountains and Sierra Madre.

“It’s not as if the population has exploded and ... we had 200 of them at one time and have 15,000 now. It’s that we always had a lot of them; we just didn’t recognize their relatedness,” deVos said.