A coalition of wildlife advocates filed a lawsuit against the U.S. Fish and Wildlife Service (USFWS) over its 2022 decision to deny Endangered Species Act (ESA) protections for the Sonoran Desert tortoise, arguing that the agency ignored science and violated federal law.
The Desert Tortoise Council, Tucson Herpetological Society, Western Watersheds Project and WildEarth Guardians—represented by the Western Environmental Law Center—filed the federal lawsuit in the U.S. District Court for the District of Arizona, claiming the agency disregarded the best available science, used flawed habitat and population models, and reversed earlier findings from 2010 to 2014 that supported listing the tortoise as a threatened species.
The coalition argues the agency ignored evidence of population declines and mounting threats. The lawsuit also claims that the agency dismissed cumulative threats, such as habitat loss, invasive species and grazing, and relied too heavily on non-binding conservation measures from a 2015 agreement with Arizona without thoroughly assessing the species’ status across its range.
“The Fish and Wildlife Service’s decision to deny protections to the imperiled Sonoran Desert tortoise was flawed from the start because it was based on a purely speculative and overly optimistic population estimate,” said David Woodsmall, attorney with the Western Environmental Law Center representing the groups.
“The agency also severely downplayed likely future effects to the tortoise from increased drought frequency and severity,” Woodsmall said. “We are disappointed to have to bring this case, but the agency simply refuses to follow the best available science as required by law.”
Background
In 2008, environmental groups petitioned the USFWS to list the Sonoran Desert tortoise as a threatened or endangered species under the ESA. The following year, the agency issued a positive 90-day finding, determining the petition contained substantial information warranting further review.
In 2010, after conducting a full status assessment, the agency concluded that listing the tortoise as threatened was warranted due to a range of serious and compounding threats. These included habitat loss and fragmentation due to development, grazing and harvesting, as well as increased wildfire risk from invasive plant species. USFWS found that many of these threats act synergistically and are expected to worsen, projecting that 98% of the species’ habitat in Mexico and nearly half in Arizona could be lost or degraded in the foreseeable future, threatening the tortoise’s long-term survival.
In subsequent reviews from 2011 to 2014, the USFWS found that listing the tortoise as threatened under the ESA was warranted.
In 2015, the agency released a candidate conservation agreement with state and federal agencies to address threats to the Sonoran Desert tortoise. Although the agreement acknowledged the species still qualified for ESA protection, its goal was to reduce threats in Arizona to avoid a formal listing. Court documents note that the agreement lacked binding commitments or regulatory enforcement, and any party could withdraw with notice.
That same year, the agency issued a revised species status assessment, estimating a quasi-extinction risk of 11-32% over a 200-year period. Environmental groups argue this assessment led to the agency’s flawed “not warranted” finding.
Environmental groups challenged the finding in 2019 and filed a lawsuit, asserting that the USFWS had ignored the best available science. The lawsuit led to a settlement approved by the U.S. District Court for the District of Arizona, which required the USFWS to revisit its finding. In 2021, USFWS released a revised species status assessment, but court documents show the agency continued to rely on limited data from just 17 long-term monitoring sites in Arizona and a habitat model it described as “very coarse.”
According to court documents, despite scientific projections forecasting a median decline of nearly 87% in Arizona tortoise populations under a high climate change scenario, USFWS again issued a “not warranted” finding in February 2022.
The agency based its decision on the same limited data and models, assuming stable population trends and adequate juvenile recruitment, while omitting projected declines expected between 80 and 125 years from now. The lawsuit argued this approach violates the ESA by failing to use the best available science.
The coalition asked the court to declare that USFWS violated, and continues to violate, federal law in its decision-making regarding the Sonoran Desert tortoise. They are also seeking to set aside and vacate the agency’s 2022 “not warranted” finding. Finally, the coalition requests the court remands the matter with instructions to comply with the ESA and the Administrative Procedure Act. — Charles Wallace, WLJ contributing editor
