Local lizard may be named an endangered species

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Flat-tailed horned lizard Photo courtesy Arizona Game & Fish

Flat-tailed horned lizard
Photo courtesy Arizona Game & Fish

The California Fish and Wildlife Commission is set to consider whether the flat-tailed horned lizard, whose habitat includes the Algodones and Imperial sand dunes west of Yuma, should be listed as endangered.

The Center for Biological Diversity’s petition to the state seeking endangered status was accepted by the department’s staff and sent on to the commission, which is set to vote on whether to name it as a “candidate species” at its Feb. 11-12 meeting in Sacramento.

If it does, the department staff will have a year to conduct further study before the commission determines whether the listing is warranted.

The rare lizards’ habitat spills over the Colorado River into the Yuma area, but most of it falls into the inland California deserts of Imperial and Riverside counties, which is why the Tucson-based center is focusing on getting state designation for the species, said Ileene Anderson, public lands desert director for the center.

She said much of the research done on the lizards has been spotty, using outdated methods or scant numbers to determine whether the population has been going up or down.

Some research has honed in on a section of the overall habitat, she said: “Actually, in the areas people have looked, there have been nothing but declines.” Some of the best data has come from the Marine Corps Air Station Yuma, outside the recreation area, she added.

The Imperial Sand Dunes Recreation Area managed by the federal Bureau of Land Management covers 164,000 acres of sandy dunes and rocky desert land running northwest from the Mexican border about 15 miles west of Yuma.

It’s a popular destination for off-road vehicle enthusiasts, and 127,000 acres are open to all-terrain vehicles and similar devices, with the BLM saying it attracts more than a million visitors a year.

Another 9,000 acres is closed for protection of the endangered Pierson’s milkvetch plant, and the rest, known as the North Algodones Dunes Wilderness, is also closed, according to the recreation area’s web site.

The BLM’s recent opening of 43,000 more acres to off-road vehicles is cited by the Center for Biological Diversity as one example of policy decisions adversely affecting the lizards since an interagency management agreement to protect the lizard was reached in 1997.
A court decision cleared the way for the BLM to open the additional land to recreational riders, as part of a management plan to protect the milkvetch and other species. According to a BLM map most of the recreational area south of Highway 78, which runs east from Brawley, Calif., is open to OHVs.
Larry LePre, a BLM biologist, said it’s difficult to get a handle on population decline or growth of the “cryptic” lizards because they’re so effectively camouflaged against the desert by their skin color. “Also, their typical behavior is to hide underground with just their heads above the ground, so they’re very difficult to see,” he said.

As a result, he doesn’t have any real indications the lizards’ numbers are going up or down, he said.

He said the sandiest dunes which get the most OHV action generally aren’t prime lizard habitat, because they don’t have as many of the harvester ants the species feeds on, in comparison to lower areas.

Anderson said this isn’t necessarily the case, as the western edge of the Algodones Dunes can have a higher concentration of the harvester ants. And technology has improved greatly over the years, to where animals can be fitted with “tiny GPS systems” or microchips so scientists will know whether they’re catching the same animal over and over again, or encountering new ones.

She said there’s no doubt the amount of suitable habitat for the lizards is decreasing due to the expansion of recreation, agriculture, urbanization, solar farms and other human activities. “That’s particularly bad for this lizard, because its whole strategy to avoid being captured by predators is to literally freeze in place,” she said.

The center’s petition recommended actions to protect lizard habitat include closing more areas to off-road recreation, along with better fencing and enforcement against trespassing by vehicles and people. It also suggests burying transmission lines which can serve as perches for birds who feed on the lizards, keeping solar energy projects off suitable habitat, and government acquisition of private land for conservation.

The majority of the lizard’s habitat is in northwestern Mexico, where it’s listed as an endangered species. But management efforts there and in the U.S. may not be enough to protect the species from extinction, the petition said.

BLM spokesman Steve Razo said it’s hard to know ahead of time how a decision by California to list the flat-tailed horned lizard as endangered would affect the amount of sandy dunes open for off-road recreation, in part because the state and federal governments are currently collaborating on efforts to preserve the population.

“We currently have a conservation and management plan in place for the flat-tailed horned lizard which the state and state parks are part of,” he said. The plan includes setting aside management areas in the East Mesa, West Mesa and Yuha Desert, which are away from the most frequently-traveled dunes.

The center’s petition said limited off-road vehicle use is permitted within the management areas, and the BLM doesn’t do enough to enforce the rules that are in place. All of them border open recreation areas, it said, so some or all of the management areas should be closed to off-road vehicles, the petition maintains.
Ann Walker, spokesperson for the Yuma Visitors Bureau, said there’s little data about the economic impact of the dunes on the Yuma area, in part because the dunes are across the state line.

“We consider ourselves the gateway to the dunes area, just because we’re closer,” she said. “When you need to go get more gas, Yuma is only 15 minutes away, as opposed to about 40 from El Centro. And all the duners from Phoenix come through Yuma anyway.”

Adult flat-tailed horned lizards are 2- to 3.5-inches long excluding their flattened tails, and weigh well under 1 pound. Their long, sharp horns put them in the family of horned lizards, among which they have one of the smallest ranges of any species. The average lifespan is 3 years, and their predators include hawks, snakes and squirrels. Many are also run over by vehicles, both on- and off-road.

The species has been the subject of a prolonged battle between the Center for Biological Diversity and other environmental groups and the federal government over designating it as threatened or endangered.