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New Studies Highlight Harms to Desert Tortoises, Need for Better Protection in California’s Deserts

New Studies Highlight Harms to Desert Tortoises, Need for Better Protection in California’s Deserts
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LOS ANGELES— New studies by federal scientists provide conclusive evidence that imperiled desert tortoises are harmed by livestock grazing and off-road vehicles, and that physically moving desert tortoises to new home territories to mitigate destruction of their habitat causes serious health threats to tortoises.

Dr. Kristin Berry of the U.S. Geological Survey in California and colleagues published a recent study in Herpetological Monographs that found that the management area with the longest history of protection, intact fencing and exclusion of livestock and vehicles had significantly more live tortoises and lower death rates than two other areas that had lesser or no protections. Christina Aiello of the U.S. Geological Survey in Nevada and colleagues published an article in Animal Conservation that found serious health threats from desert tortoise translocation — a commonly used method to move tortoises off of their home territories.

These studies highlight the urgent need for better protection of the animals’ habitat in California’s deserts, where two land-management efforts — one to develop industrial-scale renewable energy and another to reduce ubiquitous off-road vehicle routes and address grazing practices — are currently in the planning stages.

“These studies come at a critical moment for tortoises, which continue to decline and struggle in California’s deserts,” said Ileene Anderson, a senior scientist with the Center for Biological Diversity. “If we want desert tortoises to survive, we’ve got to stop subjecting them to large-scale grazing and ORVs and rethink the idea that we can simply move them out of harm’s way, which may turn out to be fatal for many of them.”

A key finding of the Berry et al. study is that livestock grazing, as well as roads and trails, results in profound changes to native habitat. Livestock compete with desert tortoises for key food plants, especially in critical foraging seasons of spring and after summer rains; cows and ORVs trample and collapse tortoise burrows.

The Desert Renewable Energy Conservation Plan will facilitate new industrial-scale solar and wind projects in the California desert while also protecting the desert tortoise and other rare animals and plants; yet it would still allow off-road vehicles and livestock grazing in important tortoise habitat. This research confirms that to protect the tortoise, all threats must be eliminated. Further, the practice of “translocating” tortoises may cause deadly disease outbreaks.

The Bureau of Land Management’s revised West Mojave plan, expected in early 2015, will identify an off-road vehicle route system and propose standards for grazing on 3.2 million acres of public lands in a key recovery unit for desert tortoise.

“These two studies confirm that significantly decreasing the number of roads, eliminating livestock grazing, and avoiding translocation of desert tortoises are all necessary to keep our beloved state reptile from extinction,” said Anderson.

Background
The desert tortoise has been on California’s state endangered species list as a threatened animal since 1989 and the federal endangered species list as a threatened animal since 1990. Populations throughout its range continue to decline.

A recovery plan in place since 1994 has been rewritten once but has largely not been implemented. Critical habitat was designated in 1994, but grazing was only eliminated in a portion of the tortoise’s critical habitat. Harmful impacts continue to occur to critical habitat.

Desert tortoises are long-lived (60 to 80 years in the wild), spend most of their time in their burrows escaping heat and cold, know their home territories well, and can survive several years without water if necessary.

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 800,000 members and online activists dedicated to the protection of endangered species and wild places.