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Dunes sagebrush lizard Sceloporus arenicolus
ESA status: none
In a remarkable landscape in southeastern New Mexico, there is a unique miniature world tucked in amidst the ruddy sand dunes. Tiny oak trees only 3 feet tall, known as shinnery oaks, surround a wind-hollowed depression in the sand, a little over 300 cm deep and around 30 m long. In this tiny realm, and rarely more than six feet away from its favorite miniature tree the shinnery oak, lives a dunes sagebrush lizard.
Little dunes sagebrush lizard kingdoms such as this are scattered among shinnery oak sand dunes in southeast New Mexico and a tiny area of southwestern Texas. The dunes sagebrush lizard (formerly known as the sand dune lizard) has one of the smallest ranges of any lizard native to North America and has incredibly specific habitat requirements, right down to the size of the sand grains in its shinnery dune blowout (medium-sized, not too coarse or too fine). In its tiny habitat, it lives a tiny life (one to two years), eats ants, small beetles, crickets, grasshoppers, and spiders, and has a tiny family (one or two clutches of eggs, with three to six eggs per clutch). But though the lizard chooses its home very carefully, there are certain dangers in the modern age that it couldn’t have taken into account. How was this lizard to know that its specialized shinnery oak sand dune habitat lay smack on top of the Permian Basin? And that this basin would become one of the most active oil fields in the U. S.? Yet that is exactly the reason why the dunes sagebrush lizard is in immediate danger of extinction.
Oil and gas extraction is the primary threat to this lizard and its habitat, and the main reason why it has declined precipitously across its range and is acknowledged by the Fish and Wildlife Service (FWS) to be facing severe and imminent threats to its survival. This lizard is extremely sensitive to habitat disturbance; studies conducted on Bureau of Land Management (BLM) land indicate that a single well reduces the dunes sagebrush lizard population by almost 50 percent in the area extending 253 meters around the well (50,152 square meters). Densities of 30 wells per square mile would reduce lizard populations by 50 percent, and 15 wells per square mile would reduce it 25 percent. Disturbance from well pads and death from leaking pipelines also contribute to the decline of dunes sagebrush lizard populations, as well as peripheral activities such as seismic exploration, during which lizards and their nests can be crushed.
As if that wasn’t enough, herbicide control of shinnery oak has eliminated almost a quarter of the lizard’s already small habitat. The lizard, for reasons that are still unknown, cannot live without these tiny trees, and herbicide removal of the oaks resulted in a 70 to 94 percent decline in lizard populations over multiple years of study on herbicide-use sites. Off-road vehicles can crush lizards and their eggs and destroy their shinnery oak habitat, and ORV use has increased substantially over the last decade. Given ORVs’ rise in prevalence, the BLM itself acknowledges that careless riders may forge beyond designated areas and into “special status species habitat,” crushing everything in their path.
The lizard has been on and off the Endangered Species Act candidate list since 1982, when it was made a Category 2 candidate as a subspecies. After being reclassified several times due to population declines and a “typographical error,” it was dropped during a general purge of the candidate list in 1996. By that time it was recognized as a full species. It was returned to the candidate list in 2001 with a listing priority number of 2, the highest rank possible for a full species, indicating that it faced high-magnitude, imminent threats to its survival. After a long wait, it was finally proposed for listing in late 2010. Meanwhile, scientists had been warning for over a decade that the dunes sagebrush lizard’s extinction was imminent. Unfortunately, the lizard was denied protection when the FWS withdrew its listing proposal in June of 2012. The agency contends that current conservation agreements are adequate to protect this imperiled reptile and its dwindling habitat. We will monitor these agreements closely to ensure they are working.
Dunes Sagebrush Lizard Distribution in the Permian Basin
Dunes Sagebrush Lizard Distribution and Oil/Gas Development in New Mexico
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photo credit: Public domain