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Topic: Flora & Fauna     Department: Letters

Tortoise treatise, critiqued

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Emily Green's Aug. 5 article "Mojave Squeeze," states that, in 2008, "California's habitat conservation plans (were) superseded by a new 'Desert Renewable Energy Conservation Plan.' " In fact, the DRECP has not superseded anything; a draft environmental impact statement has yet to be released.

Ms. Green failed to note that the final biological opinion for the Army's expansion of Fort Irwin addressed the loss of approximately 23,000 acres of critical habitat, and did not mention that Congress authorized $75 million for the Army to mitigate the impacts of expansion.

With regard to translocation, Green quotes Dr. Kristin Berry's summary of the fates of translocated tortoises: 84 of 158 died. However, soon after the Army translocated the tortoises, the desert was enveloped in a drought. Researchers determined that the mortality rate among the translocated desert tortoises was not statistically different than that of resident animals and of control animals.

Additional work on desert tortoises in the translocation area showed that researchers could not detect any statistically significant differences in stress hormones or reproduction among translocated, resident, and control animals. Finally,  Green should have noted that mortality rates of all three classes of desert tortoises had dropped to approximately 1 percent within a few years of the translocation.

I am the author of the U.S. Fish and Wildlife Service's biological opinions for the expansion of Fort Irwin. These opinions are mine, not those of the Fish and Wildlife Service.

Raymond Bransfield
Ventura, California

Emily Green responds

Mr. Bransfield is correct: The Desert Renewable Energy Conservation Plan is now more than a year overdue (and the BLM's solar environmental impact statement is also ongoing). Nonetheless, state and federal emphasis on renewable energy, beginning in 2008, has resulted in rapid solar and wind development in tortoise habitat covered by habitat conservation plans.

Owing to space, the article did not address in detail the long negotiations over Fort Irwin, including the changing footprint of the expansion into critical habitat, or the $75 million for land purchases. However, there is no evidence that this mitigation abetted tortoise recovery.

Dr. Berry was among many researchers to remark that it is impossible to accurately assess natural death rates of resident tortoises from drought after impacting them by releasing dozens of other tortoises. Death rates and causes can only be established once Fish and Wildlife publishes population studies of resident wild tortoise numbers in the Mojave, which remain unfinished 24 years after the tortoise was first listed.

The 2012 study on the stress hormone corticosterone could be interpreted as indicating that stress is not a factor in translocation, but the authors acknowledge that hormone levels may not be not reliable indicators of translocation stress. The propensity of translocated animals to wander and succumb to predation, vehicles and starvation has been well documented. No mortality data were offered for the translocated animals in the hormone studies.

Fish and Wildlife has relied on short-term studies (less than five years) to argue for translocation while never publishing mortality data for its longest and largest experiment, covering 15 years of moving more than 9,000 tortoises to the Large Scale Translocation Site near Jean, Nev.

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