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A Nonnative Tree, an Invasive Beetle, and the Endangered Bird Caught in the Middle

Court says federal government must clean up the mess it helped make of riparian ecosystems in the US Southwest

The intentions were noble. The results another thing entirely.

Back in the early oughts, the federal government introduced one invasive species to fight another in the US Southwest. The idea was to rid the region of a hard-to-root-out plant wreaking havoc on fragile river habitats, but one unfortunate result of the effort was the elimination of habitat for an already endangered avian species.

photo of southwestern willow flycatcherPhoto courtesy of US Fish and Wildlife ServiceThe endangered southwestern willow flycatcher migrates to the US southwest each spring to breed. It has adpated to nesting in nonnative tamarisk as the trees have spread across the region.

Salt cedar, or tamarisk (Empidonax trailii extimus), is native to Eurasia, where it is employed primarily as ornamental landscape. It was introduced to the US southwest in 1887 in an effort to stem erosion, and quickly became the bane of southwestern rivers due to its intensive water use and prolific seed dispersal.

Congress passed a law empowering the federal government to find a remedy. In 1997, under the auspices of the Plant Protection Act, the US Department of Agriculture (USDA) decided to import another invasive, the Diorhabda elongate, or tamarask leaf beetle, a Japanese beetle with an appetite for salt cedar.

But there was a flycatcher in the ointment. In 1995, the US Fish and Wildlife Service (FWS) had designated the southwestern willow flycatcher, a tiny bird that migrates to the southwest each spring to breed, as endangered. As tamarisk had taken over in the region, the songbird had adapted, making the flowering tree work as a nesting place in lieu of the disappeared cottonwoods, buttonbush, and willow it preferred.

As such, the beetle represented a threat to the flycatcher's habitat. Birders and scientists alike told USDA's Agricultural Research Service (ARS) and Animal Plant Health Inspection Service (APHIS) entities just that.

The complication triggered “consultations,” as required under the Endangered Species Act (ESA), with the US Fish and Wildlife Service.

Fish and Wildlife expressed reservations that echoed concerns of the bird's advocates, noting that without replacing the salt cedar with native vegetation, the flycatcher would have nowhere to nest. But the service eventually signed off on the beetle plan, on the USDA's claim the program would have “no significant impact” on the songbird's ability to survive.

photoname Photo by Dan Bean/Colorado Department of AgricultureTamarisk beetles dine on a salt cedar tree.

Concessions were made. No beetles would be released within 200 miles of known songbird habitat. They would be monitored in cages for one year before being unleashed and then tracked for two years after. The releases were initiated in 2005.

A parallel release later proposed by APHIS, above 38 degrees north latitude — the line dividing the northerly states of Utah and Colorado from New Mexico and Arizona to the south — was considered safe on the assumption the beetle would not drift south into flycatcher habitat, because the winter would be fatal.

ARS estimated a 75 percent to 85 percent reduction in salt cedar in beetle-release regions over a five- to ten-year period, during which the return of native plants might be expected. If salt cedar mortality outpaced the regeneration of the native flora, consultations were pledged.

But assumptions about the program proved wrong. The beetle moved fast and grew in numbers. The fatal winters were not very fatal. By 2008, beetle swarms had entered flycatcher habitat in parts of Utah, Arizona, and Nevada. The number of bird pairs plummeted.

Individual songbird populations have also disappeared. “These were small in number, but important in connecting larger populations,” according to Robin Silver, co-founder of the Center for Biological Diversity, who estimated there are approximately 2,000 flycatcher pairs spread out across California, Arizona, New Mexico, Nevada, and Utah.

In 2010, the USDA admitted it was licked and terminated the program.

“They proposed one invasive species to eliminate another invasive species,” says Bill Eubanks, an attorney representing the Center for Biological Diversity and Maricopa Audubon Society in a lawsuit against the federal government. The plaintiffs sued the USDA and APHIS in 2013 asserting the agencies had essentially washed their hands of a problem that they had created.

“It is a highly unique situation factually,” said Eubanks. “A federal agency has been intimately involved with proactively changing the ecosystem without accounting for the repercussions.”

Complainants argued the government had a duty to fix what it had broken. They invoked the rarely litigated section 7(1)(a) of the ESA.

According to Eubanks, the section requires all federal agencies to ensure their actions won't negatively impact an endangered species. “It's a novel claim,” he said. “Some think it vague.”

The government's response to the suit was largely procedural. APHIS pleaded limited authority, and said the original plan included mitigation measures. Designated habitat incursions, the agency asserted in legal briefs, were the result of an unauthorized beetle release in Utah for which it was not responsible.

The government ultimately litigated the matter to its court-ordered resolution.

“We won,” explained Silver. “The judge recognized that the agencies are not doing anything to mitigate the problem they created. He said federal agencies must ensure their actions are consistent with preserving species as opposed to annihilating them.”

The judge does not appear to have come by his decision easily. At a March 31, 2017 hearing in his Las Vegas, Nev., courtroom, Judge Richard Boulware weighed the matter: “Let's take the approach that [defendants] want to do everything they could do, but one of the lessons that maybe they learned from this was, if you do one thing here, something else can be adversely affected. And so they may say, 'Look, we realize now that we can't just fix one polka dot, right, on this series of polka dots, because if we move one they all start shifting. Right?'”

On April 13, Boulware followed up his initial finding that the government had failed to clean up a mess of its own making with a proposed, court-ordered remedy. USDA and APHIS have 15 months from the date of the order to develop a plan for the mass planting of native vegetation “to ensure that suitable substitute habitat exists” to combat the beetles' impact. The court further prioritized 18 target locations for remediation.

Said Silver: “The fact that Judge Boulware will remain so involved will help force USDA/APHIS to finally provide some relief for the flycatcher.”

Mitigation will not be easy to accomplish, Silver said. The beetle can devour the tamarisk above the ground, but the deep roots remain, drawing down water table levels and impeding the ability of replanted cottonwood stands to take hold.

As for the Asian imports, they are here to stay. “There is no way to get rid of these beetles,” states Silver. “They reproduced rapidly. All the salt cedar in the Grand Canyon and on the Virgin River is dead, but the swarm will reproduce and eat as long as they are able to move elsewhere.”

Stephen Siciliano
Stephen Siciliano is a writer living in Los Angeles. He has extensive experience as a reporter covering endangered species issues in the American southwest and northern Mexico.

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