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.