ST. GEORGE —While the county continues to monitor the predation of the Mojave desert tortoise by ravens within and around the Red Cliffs Desert Reserve, some officials are frustrated more active measures aren’t being taken to protect the tortoise.
“Monitoring the demise of tortoises seems idiotic to me,” Ivins Mayor Chris Hart said as he sat with other members of the Habitat Conservation Advisory Committee, the body that oversees the Habitat Conservation Plan – or HCP – that guides management of the reserve.
“It’s good to know it’s happening, I guess, but monitoring without taking some immediate action seems futile to me,” he said.
Hart’s comments followed a presentation by biologist Mike Schijf reviewing recent findings and conclusions of the raven monitoring program. The presentation was a follow up to a similar review given in May that labeled the crow as a rising threat to the recovering desert tortoise population.
The ravens like to target tortoise hatchlings and juveniles, as their shells have not yet sufficiently hardened to prevent the birds from cracking them open and picking at the tortoises’ insides with their beaks.
The raven monitoring program started in 2015, with HCP staff and others finding between four and eight instances of young tortoises killed and eaten by ravens each year through 2018.
However, this year has seen more desert tortoise carcasses than previous years, with most of the tortoise predation occurring near a known raven nest site on Red Mountain near Ivins, which Schijf said accounts for 16 incidents of predation activity.
“We found a clustering of carcasses up there,” he said.
Outside of the Red Mountain/Ivins area, the level of tortoise predation in the rest of the desert reserve is on par with previous years.
The Red Mountain nest is one of 17 known nest sites throughout the Red Cliffs Desert Reserve and surrounding area monitored by the program. In previous years two primary areas of concern have been Paradise Canyon and T-Bone Mesa, as that is where utility lines are located that serve as a place where ravens love to perch and attack tortoises.
While these areas are still seen as a priority to be dealt with, the ravens of the Red Mountain nest site are at the top of the monitoring program’s concerns.
“The possibility is there for large scale predation to occur,” Schijf said of the raven issue in general.
Recommendations for dealing with the raven issue involve increased monitoring in areas like the Red Mountain nest where predation is high, as well as public education efforts that can reduce human created subsidies – like access to trash – that help sustain and grow raven populations.
The use of 3D-printed “techno tortoises” that could be used to record raven attacks, as well as create a taste-aversion for the bird by being laced with particular chemicals, was also mentioned.
Schijf said another option is egg oiling. When applied to raven eggs, the oil causes the embryo to stop developing and is considered a nonlethal and humane method of bird population control. While keeping the local raven population from increasing, Lura Snow, the HCP’s outreach coordinator, previously told St. George News. She added the egg oiling also helps stop the ravens from teaching a new generation about how easy it is to pick off the smaller tortoises.
It is also hoped that by oiling the eggs, it will make the ravens think the area they’ve chosen to nest isn’t viable for egg laying, and they will go somewhere else.
The HCP administration has submitted applications to use egg oiling to the Utah Division of Wildlife Resources, U.S. Fire and Wildlife Service and the Bureau of Land Management.
It is also hoped that desert reserve staff will be able to work with the BLM on destroying the Red Mountain raven nest site before the 2020 nesting season, Schijf said.
However, since the nest is on federal land managed by the BLM, gaining access to the area for predator-control purposes must be reviewed through the process set up by the National Environmental Policy Act, which can take time.
Earlier this year, Dawna Ferris-Rowley, the BLM representative on the HCP advisory committee, said the BLM didn’t have the additional staff needed to initiate a study into the matter. However, there was talk of contracting a third party for this purpose.
Other frustrations to moving predator control measures along is the fact that Red Cliffs Desert Reserve does not have a raven control program that sets guidelines on how to handle the problem.
Ferris-Rowley said she’d like to see an incremental plan in place to address the ravens, as well as a study done to determine how much of the tortoise predation by the birds could be considered natural.
“I want to know what’s natural before we go in with a bazooka,” she said.
A raven management plan currently exist in California, Schijf said. He recommended examining the plan to see if it can be applied to the desert tortoise recovery unit in the reserve.
Hart, as well as Hurricane mayor and fellow committee member John Bramall, both said something needed to be done and noted their shared frustration.
However, the U.S. Fish and Wildlife Service representative on the committee, Larry Crist, said there needs to be a foundation and to “make a case for it first.”
Various state and federal agencies involved in the creation and approval of predator control actions have their own priorities and may not see the raven issue as a pressing one, Crist said, expressing a need for patience for the process.
While the ravens are seen as a threat to the tortoise population, particularly as their population growth mirrors that of the county, it was noted during the committee meeting that the possibility of a wildfire in the reserve is currently considered a far bigger threat for the time being.
While the ravens pick off a tortoise hatchling here and there, a wildfire has the potential to decimate a large part of the entire population.
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