Update: Farallon Rodenticide drop

“Short of offshore oil drilling, this is the biggest threat to the sanctuary that I have ever seen,” said Richard Charter, senior fellow with the Ocean Foundation who helped create the Greater Farallones National Marine Sanctuary that surrounds the Farallon Islands.

The South Farallon Islands are a national wildlife refuge that hosts the largest seabird breeding colony in the contiguous U.S. About 350,000 seabirds from 13 species use the island, including about half of the world’s population of ashy storm petrels. “

Marin IJ: Farallon Islands mice eradication plan nearing review

A house house near its den on the Farallon Islands on Oct. 13, 2011. (IJ photo/Frankie Frost)

 

PUBLISHED: | UPDATED: A controversial proposal to spread rodenticide-laced bait on the South Farallon Islands to eliminate invasive mice for the benefit of birds is expected to return for the California Coastal Commission’s review in mid-June.

The U.S. Fish and Wildlife’s proposal to airdrop and hand place about 2,900 pounds of cereal pellets laced with brodifacoum — a rodenticide partially banned in California — on the islands to eradicate the estimated 60,000 or so mice will be no different than what was presented to the commission in July 2019, according to agency spokeswoman Erin Curtis.

“We are returning to the commission to respond to their questions from last year’s hearing and provide a more thorough presentation on the proposed project,” Fish and Wildlife Service spokeswoman Erin Curtis wrote in an email.

At its July 2019 meeting, the coastal commission peppered the federal agency’s representatives with questions and raised concerns about the agency’s ability to prevent other animals, such as gulls and burrowing owls, from ingesting the poison bait and ending up on local beaches. Models presented to the commission suggested there would be a 63% decline of the ashy storm petrel population if the mice were to remain.

Critics of the proposal say they understand the need to address the mice impacts on the island’s ecology, but argue the federal agency should consider other alternatives to poison.

“Short of offshore oil drilling, this is the biggest threat to the sanctuary that I have ever seen,” said Richard Charter, senior fellow with the Ocean Foundation who helped create the Greater Farallones National Marine Sanctuary that surrounds the Farallon Islands.

After its plan received poor reception from the Coastal Commission, the Fish and Wildlife Service temporarily withdrew its application to obtain California Coastal Act compliance certification last year with plans to return.

About 50 other eradication methods were reviewed by the Fish and Wildlife Service as part of its environmental review including contraceptives, individual traps and pathogens. They were either deemed infeasible or inadequate to stop the mouse problem.

The agency acknowledged that other species such as Western gulls and burrowing owls will likely ingest the poison, but that it use several techniques such as hazing, monitoring, carcass removal, bait destruction and others to keep the by kill below significant levels. Between 14,000 to 32,000 Western gulls would inhabit the islands during the winter when the bait drop is planned to occur, with about 1,700 gulls having to die before any long-term effects on the population would occur, the agency review states.

The Fish and Wildlife Service’s environmental review also states that should the poison bait drift into the ocean, the rodenticide would likely not show up at detectable levels in the water and near-shore fish and marine invertebrates.

The South Farallon Islands are a national wildlife refuge that hosts the largest seabird breeding colony in the contiguous U.S. About 350,000 seabirds from 13 species use the island, including about half of the world’s population of ashy storm petrels. The mice, believed to have been introduced by ships in the 19th century, have been wreaking havoc on the island’s ecosystem in a variety of harmful ways, according to the Fish and Wildlife Service.

In addition to eating the seed bank for native plants, competing for food of island-specific species and even eating eggs and chicks of some of the nesting birds, the mice attract predatory burrowing owls to remain longer than normal on the island, the agency states. Normally, the owls stay for a few days on the islands for their fall migration, according to the Point Blue Conservation Science group, which has been monitoring birds and wildlife on the islands for about 45 years and provided data that is used in the Fish and Wildlife Service proposal. But the mice provide an ample ongoing food source, incentivizing owls and other raptors to stay for weeks. When the mouse population crashes during the winter months due to low food supply, the owls turn to the ashy storm petrel as their new food source.

Each of the six to 12 owls that inhabit the islands during the winter can kill 60 to 70 petrels including breeding petrels, which has an impact on the population, according to a Point Blue study released last year. There are an estimated 5,000 to 10,000 breeding ashy storm petrels in existence, according to the study. Point Blue’s study states removing the mice would have a significant impact on restoring the petrel population.

The proposal has sparked a heated debate about the safety of using rodenticides on a national wildlife refuge and marine sanctuary. This week, the marine sanctuary’s advisory council, which advises sanctuary superintendent Maria Brown, held a meeting on the proposal and approved a resolution seeking information about the plan.

Information requested include a list of sanctuary species that could be affected; a request for the Fish and Wildlife Service to respond to the questions raised by Brown in a February 2019 letter; and to specify the accuracy of helicopter bait drops among other information, according to the sanctuary’s media specialist Mary Jane Schramm. A copy of the resolution was unavailable on Thursday, according to council members and Schramm. The sanctuary does not have authority to approve or disapprove the project, but is able to weigh in as the Fish and Wildlife Service secures permits and approvals from other agencies, Schramm said.

There is disagreement among some council members about whether the Fish and Wildlife Service has adequately answered those questions. Charter, who is one of the council’s conservation members, argues the agency has not provided adequate information about the potential impacts the poison could have on non-targeted species that could potentially end up on local beaches.

“What we’re trying to do is get the science out into the sunlight,” Charter said. “Groups in charge of the sunlight are not cooperating. We felt we had to put that in a resolution.”

Council member and Point Blue California Current program director Jaime Jahncke said the federal agency has answered many of the questions while others will be answered as it develops more detailed implementation and operations plans.

“I believe there are some concerns from some individuals about the methods that will be used and those issues were brought up to the staff several times,” Jahncke said. “Based on what we learned from the service, the benefits of the project are much greater than any potential short -lived impacts.”

Marin County Integrated Pest Management Commission chairwoman Kraemer Winslow spoke at the meeting to advocate for an alternative option.

“The mice have been on the southeast Farallon Island for over 100 years,” Winslow said. “The ashy storm petrels have survived with up and down populations all this time. Interestingly, they have not been listed as endangered. It seems this proposal is once again about a solution looking for a problem.”

The petrels are listed as a species of conservation concern by state and federal agencies and listed as endangered by the International Union for Conservation of Nature.

Loretta Mayer, cofounder and former CEO of the Arizona-based biotechnology company SenesTech, which developed the rat contraceptive Contrapest, said that her current work with the FYXX Foundation she cofounded is looking to create a similar contraceptive tailored to mice. While she said a totally different product would have to be developed and approved, which would take a lot of time, Mayer said they would look to potentially obtain an experimental use permit from the Environmental Protection Agency.

“I’m willing to work for an alternative and if that alternative can be useful, I’m happy to make it available to any agency,” Mayer said.A copy of the South Farallon Islands Mouse Eradication Project can be found at bit.ly/2vQ9Nm0.