Protecting our tortoise habitats
Report: More published research needed to manage desert reptiles
Benjamin Spillman
The Desert Sun
August 14, 2006
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It sure makes sense - barring ATVs from the fragile habitat of the desert tortoise would protect the charismatic reptiles from being crushed alive in their burrows.
But it would be a whole lot easier to justify off-road restrictions and other controversial tortoise-related measures if scientists kept better track of the results.
That's the conclusion of a new report by the U.S. Geological Survey. It says there should be more published research to help desert land managers make scientifically sound decisions about how best to protect fragile tortoise communities.
"We have a lot of information about threats to tortoise populations," said Roy Averill-Murray, Desert Tortoise Recovery Coordinator for the U.S. Fish and Wildlife Service. "Where we have fallen short is in the scientific follow-up."
The report was published last week and could have an impact the way scientists and land managers revise a 12-year-old recovery plan aimed at reviving populations of the subterranean-dwelling reptile, Averill-Murray said.
Authors of the paper say it is especially important to document the results of controversial and expensive measures taken on behalf of the tortoise.
"People are keeping track of what is being done. But there are not many studies on whether it is doing any good," said William Boarman, a USGS scientist emeritus who worked on the report. "We need to know if these actions are successful, particularly if they are costly or controversial."
Boarman and William B. Kristan of California State University, San Marcos studied 54 measures of the effectiveness of tortoise recovery from 45 studies designed to evaluate changes following a specific tortoise-protecting action. They found the research by studying 395 documents in biologists' files and published literature.
Boarman said it makes sense most of the actions - like consolidating desert four-by-four traffic to fewer roads to reduce humans' reach into habitat - would be good for tortoises. That could be why there wasn't much follow-up.
"You just have the gut feeling it has to help the tortoise," he said.
But studying the after-affects of recovery actions can yield valuable lessons and, in some cases, even save money.
Boarman cited an incident near Barstow where managers of a construction project were required to put anti-perch devices on miles of fencing to prevent ravens from attacking tortoises.
"That was going to cost them a lot of money," Boarman said.
But scientists were able to use research to tell construction managers that ravens don't generally attack tortoises from perches.
The construction managers changed their tortoise-protecting tactics from installing anti-perch devices to altering raven nests to keep them out of tortoise areas, Boarman said.
"They are saving money, they are getting their permit and they are doing even more for the tortoise," he said.
Finding the funds
More data would also help land managers who also walk a fine line between a mandate to protect the threatened reptile and a desire to preserve as much open access to the desert as possible.
Russ Scofield, habitat restoration coordinator for the Desert Managers Group, said scientific data can provide an oasis of neutrality in the ongoing desert battles waged by off-road and open access groups and conservation organizations.
"You have the green side that thinks we should be doing more closures. Then you have got the user side that thinks there should be less closures," Scofield said. "The best thing for (government land managers) is to make their decisions based on science."
Finding funding to do more studies will be a challenge, though. In general, funding for conservation and land management is flat or decreasing. And special interest groups are as likely to spend their money on lobbying as they are to contribute to objective science.
Boarman acknowledged that there could even be controversy among scientists. Some may argue against follow-up studies if it means limited funds are diverted from researching and implemented new ways to protect the tortoise.
"A lot of people, and for good reason, think that you should put the money into doing things," he said.
The stakes are high for the tortoise. The reptile lives in California, Utah and Nevada. In its eastern Colorado Desert range, an area that includes the Coachella Valley, its population has dropped from 10.8 adult tortoises per square kilometer of habitat in 2001 to 6.38 in 2005, Averill-Murray said.
And because of the tortoises' long life spans, even studies that start immediately will take years to get results.
"While you are collecting the information you are losing more and more tortoises and more and more habitat," Boarman said.