Common Desert Tortoise Feels the Heat
HE has creaky, scissor jaws like an armored knight, stumpy legs like an elephant, a name like a Bulgarian tennis pro (Xerobates Agassizii). He sleeps underground eight months of the year. Upon leaving his burrow, he eats grass and wildflowers and drinks water in the scorching creosote bush and yucca-tree habitat of the American Southwest. He lives primarily in desert valleys, stays away from areas of windblown sand and rock outcrops, and has little interest in sunbathing.Skip to next paragraph
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And he has survived two million years on Earth only to face probable extinction before the end of this century.
A state symbol of California, the common desert tortoise is the controversial reptile caught in an environmental imbroglio over what to do about his meteoric drop in numbers. The fight has to do not only with stopping the irreplaceable loss of a beautiful creature, but also what its plight signals about environmental health for humans.
``He is what we call an indicator species for the desert,'' says John Brode, an endangered species biologist for the California Department of Fish and Game. ``That means if he's having a hard time surviving out there, a whole lot of other plants and animals are, too.''
Studies show tortoise populations have dropped 90 percent in the last 50 years, and in the western Mojave of California, their numbers have declined 50 percent in the last seven years. Estimates were once as high as 1,000 per square mile in certain terrain. Today, environmentalists estimate that only 60,000 remain. Others say the number is as high as 1 million.
``There are a lot of environmental concerns that face not only Western but third-world societies,'' says Steve McCormick, director of field operations for the California Nature Conservancy.
``All of them are certainly worth addressing with some urgency. But very few things are as irreversible as the loss of species and habitat. Once a species goes extinct, there is absolutely no way to re-create it.''
Though few are disputing the loss of numbers, views differ as to the reasons for the tortoise's decline. Kristin Barry, researcher for the Bureau of Land Management, hangs a list of reasons on one word, people: urbanization, agricultural development and grazing, energy development, road and energy corridors that isolate tortoise environments. Further human settlement has unintentionally led to more raven habitats, and a 15-fold increase in the - predators that have devastated juvenile tortoise populations - the common raven.
``If man had not appeared in all his glory on the desert scene, the tortoise would be thriving,'' Dr. Barry says.
Maria Brashear, director of the California Desert Coalition, a group opposed to legislation restricting the use of the desert for vacationers, bikers, and recreational vehicles, sees humans' direct impact as a political smokescreen for protective legislation and red-tape measures that needlessly constrict desert use. She and others say the major reason dramatic numbers of tortoises have died is a respiratory disease. Scientists concur that significant numbers have been lost to the disease - 20 to 40 percent just last year, 70 percent from 1979 to 1989.
``No one is defending the decline of the tortoise,'' says Ms. Brashear. ``But the notion that man's presence out in the desert is seriously threatening these creatures is unproven and absurd. Laws restricting access to the landscape needlessly in red tape don't address the problem as environmentalists hope.''
Opinions differ as to whether or not the disease was introduced by captive tortoises released into the wild, and if so, how to stop its spread.
``Not linking this disease to man is like not linking cancer to smoking,'' says McCormick. ``There is actually no scientific proof, but there is so much circumstantial evidence that inferences are pretty revealing.''
The jury is still out. At each juncture, battle lines are drawn, statistics questioned, action stalled.
Whatever the reason, last month California's desert tortoise gained emergency status on the federal list of endangered species. That raises the priority of funding for research, provides for penalties for killing tortoises, and requires federal and state agencies to consult with the Fish and Wildlife Service when their plans may have an effect on tortoise populations. It also increases funds available for protection and recovery, permits fencing off highways on which tortoises are frequently killed. So far, the listing is for 240 days, enough time to consider if permanent protection is warranted.
The United States Bureau of Land Management launched a program earlier this year to poison and shoot ravens, but the program has been temporarily halted by the Humane Society of the United States.
July hearings on a sweeping desert protection bill sponsored by Sen. Alan Cranston (D) of California reiterated both environmental concerns and the needs of ranchers and others who use the desert for their livelihood and their recreation. But because of the bill's sweeping proposals - extending federal wilderness and parkland protection to nearly 8 million acres of Southern California desert - little progress is expected in the near future.