YUMA PROVING GROUND, Ariz.-- As a natural laboratory, US. Army Yuma Proving Ground has a vested interest in responsible stewardship of the land.

It is the busiest of the Army's six test centers in terms of direct labor hours and boasts the longest overland artillery range in the United States, yet a relatively small portion of the proving ground's vast ranges are subject to the impact of artillery projectiles.

YPG is located in one of the nation's most extreme desert climates, but is home to a huge diversity of wildlife, including Sonoran pronghorns, desert tortoises, wild burros, and bighorn sheep.
Smaller creatures like 15 different species of lizards are also in abundance here, and one in particular, the Mojave fringe-toed lizard, is of particular interest to wildlife officials.

"The Mojave fringe-toed lizard is a part of YPGs Integrated Natural Resources Management Plan," explained Daniel Steward, YPG wildlife biologist. "It's considered a species of greatest conservation need due to its special habitat requirements."

Other species of fringe-toed lizard not on YPG have faced major conservation concerns. This is in part because many other dune systems in the American West have faced threats from development, off-road vehicles, and invasion by non-native plants. The few remote sand dunes at YPG, on the other hand, are far away from any populated areas and rarely traversed by people or equipment.

"These lizards are specific to wind-blown sands," said Steward. "The challenging thing is that it is such a habitat specialist that the distribution of the lizards is naturally very, very fragmented. One remote dune system might be 30 miles away from the next."

Ranging in length from three to four inches, the fringe-toed lizard has a unique fourth toe on each foot. Their scales help provide traction on sandy ground, and a shovel-shaped snout makes them adept diggers. They primarily eat ants and other desert bugs, and wait for their prey to pass by before striking. Scales over their eyes, nostrils, and ears protect them from sand, and an oscillated tan coloration makes them heavily camouflaged on the desert floor.

"These animals are pretty limited to the dunes, and sand dunes are a very unique system for North America and deserts in general," said Daniel Leavitt, a herpetologist with the Arizona Game and Fish Department. "Some folks acknowledge that there is a great deal we don't understand about the world we live in, including what animals may have to offer. It's probably best to not allow these lizards to disappear."

Steward recently hosted Leavitt for a study of the Mohave Fringe-toed Lizard population at YPG. The pair was particularly interested in seeing how the habitats had faired during the region's relatively-rainy winter. One concern was the possible growth of an aggressive invasive weed called Sahara mustard, which crowds out native flora and sometimes grows more than a yard tall.

"We want to ensure the long-term viability of the fringe-toed lizard population," said Steward. "For example, if there are any ecological conditions that could harm that ecosystem, such as Sahara mustard and other invasive species, we may need to do weed control."

A look around the dunes upon arrival, however, showed nothing but native species like desert creosote, Palo Verde trees, and ocotillo plants in radiant orange and green bloom.

"The plant life in the dune system is rich," explained Steward. "The great thing about dunes is that every drop of rain goes into the ground. You don't think of sand holding moisture, but it really does."

The business of tracking the creatures takes patience. It was a still, calm day, and the otherwise pristine sands were pocked with the unique tracks of a variety of creatures, from sidewinders to field mice. The pair circled for long minutes in the growing heat, once catching sight of one lizard fleeing into a burrow hole. Finally, the pair found one sunning himself in the open. Leavitt approached with a small noose attached to a long pole and lassoed the lizard. After a brief visual inspection that showed him to be a healthy male, Leavitt released the creature onto the sand, whereupon he ran away leaving a miniature sand cloud behind. Afterward, the two inspected other sand dunes at different spots within YPG with similar results.

"It's a fascinating creature," said Steward. "Everybody's ultimate goal is to prevent the species from being placed on an endangered list, to conserve it on our own. This research gives us the information we need to be able to assess possible future impacts on this species and allows us to better support YPG's mission while ensuring conservation."

"The Army is doing a great job," added Leavitt.