Eradicating Tamarisk Trees May Endanger A Bird Species

Click on the map above to see where the tamarisk leaf beetle has spread throughout the Southwest.
September 05, 2011

Photo courtesy National Park Serivce.
Tamarisk is ubiquitous along riverbanks in the southwest.

FLAGSTAFF, Ariz. -- Government agencies, scientists and environmentalists are entangled in a predicament more complex than a thicket of tamarisk.

It all started in the mid-1800s when a pink flowering shrub was brought to the United States to control erosion. The tamarisk seedlings dug their roots in deep and flourished along the banks of rivers in the west. For the past few decades, land managers have been trying to eradicate the non-native plant, most recently using another non-native species – a leaf beetle. And that’s where things get complicated.

To many, tamarisk is a noxious weed.

“Those species can pose a great threat to overall ecosystem health and diversity,” said Lori Makarick, vegetation program manager for Grand Canyon National Park.

That’s why Makarick and hundreds of volunteers have dedicated 45,000 hours to getting rid of it. Low impact rules require them to use only hand tools to cut, dig and remove the shrubs.

“It’s incredibly intense. It’s incredibly time consuming,” Makarick said. “It’s expensive. It’s really draining.”

The tamarisk dominates huge swaths of the southwest, crowding out native plants.

It’s become the favorite home to the Southwestern Willow Flycatcher, which used to nest in the native willow.

Photo courtesy U. S. Geological Survey.
Many are worried about the Southwestern Willow Flycatcher's habitat.

Just as the songbird was successfully adapting to its new home, scientists went looking for more efficient ways to wipe out the shrub. The U.S. Dept. of Agriculture found an alternative to manually digging out the shrubs ¬– a tiny yellow and black leaf beetle from Kazakhstan with a huge appetite for tamarisk.

“I think the project has been very successful,” said Dan Bean, Colorado’s director of biological pest control.

Since the beetle was introduced a decade ago, tens of thousands of plants have been stripped of their leaves and many are dying. The beetles are moving farther faster than anyone anticipated.

“In Colorado we’ve seen a resurgence of native plants,” Bean said.

But many concerned about the endangered Southwestern Willow Flycatcher aren’t celebrating the beetles success.

The USDA didn’t think the bug would travel to southern states where the flycatcher nests.

“I don’t know if we’ll see the full extinction in our lifetime of the flycatcher because of this beetle,” said Robin Silver with the Center for Biological Diversity. “But it’s not outrageous to claim it will happen in our kids’ lifetime and in certainly our grandkids’ lifetime.”

Two years ago, the center filed suit against the USDA and Fish and Wildlife Service. That prompted federal agencies to withdraw their involvement from the beetle project. Now the center wants them to repair the ecosystem and plant native willows.

Photo courtesy Chihuahuan Desert Education Coalition.
The tamarisk leaf beetle or diorhabda elongata is from Kazakhstan and has a huge appetite for tamarisk.

“Humans have had a big impact, huge impact and we continue to have a big impact on wild places,” said Emma Wharton, the executive director of Grand Canyon Youth, a program that’s done many hours of tamarisk removal and education. “Tamarisk didn’t fall out of the sky like rain. We introduced it. So I think there is something to be said for what is our responsibility to manage or take care of that to try and keep these places that are so special as close to what they would naturally be like without human interference.”

Wharton said the agencies need to stop reacting and agree on a plan that provides a good home for the flycatcher and other species and restores some balance to the southwest.