DTA Submits Public Comment Opposing the Farallon Island House Mouse Eradication Project

Significant adverse effects on nontarget species are certain to occur. The true magnitude and duration of these impacts are unknown and understated.

Brodifacoum, the rodenticide proposed for the Farallon Islands eradication project, is so dangerous to non-target wildlife, domestic pets, and humans alike that California placed a moratorium on nearly all uses of the product on the mainland in 2020. The US EPA recognized in its review of rodenticide products in 2008 that brodifacoum is among the four rodenticides that pose the greatest risk to wildlife, and has implemented restrictions on the sale and use of this product, including that it must be contained in clearly labeled tamper-resistant bait stations. As previously mentioned during testimony in front of the California Coastal Commission and included on the Coastal Consistency Determination (April 2021), the product is still permitted, legally, for use on island eradication projects due to the complexity of island habitation. However, this exception of use does not hinder the product’s danger. The FWS plans to smother the Farallon Islands with approximately 3,500 lbs (1.45 tons) of cereal-like grain bait with two aerial applications. Additionally, Brodifacoum-infused bait will be hand-baited within caves, areas of human habitation, and other hard to reach places, to ensure that the project is “a success.” 

Read our Full Public Comment HERE

ISLAND ERADICATION PROJECTS: WHAT “SUCCESS” REALLY LOOKS LIKE

In the context of island eradication projects, efficacy and the magnitude of adverse effects of aerial broadcast rodenticide applications are difficult to predict, and remains subject to ongoing scientific debate. But mass animal casualties in the aftermath of these projects have been reported around the globe (Video: Brodifacoum drops on Rangitoto and Motutapu Islands, 2009). In 2009, a similar project on Alaska’s Rat Island led to the reported deaths of more than 420 birds, including 46 bald eagles (Ornithological Council Report, 2009). During the Alaska Rat Island project, Island Conservation—the same organization involved in the proposed Farallon Island project at issue—dropped an amount of poison that was “in excess of that recommended by an advisory panel and probably above the legal limit approved by the US Environmental Protection Agency (EPA),” according to a 2011 Nature article. Impacts on non-target species were similarly underestimated on Lehua Island, Hawaii, where invasive rodents were not eradicated after an initial aerial application necessitating “mop-up” efforts of additional poison to effectively complete the project, resulting in the death of over 400 birds. Despite the unintended deaths, both projects were declared to be “success” stories, since rodent eradication and rebounded population of the targeted island birds was accomplished. Therefore, “success” of a project is ambiguous and subjective.

While research regarding the accumulation and impact of rodenticides on marine species are limited, exposure through aquatic pathways is known to occur, and residues have been detected in fish, mussels, and limpets up to three years after application. Such accumulation poses risks to species across the food web as well as to human health. Impacts on terrestrial species including birds, mammals, and even invertebrates are well documented and must be understood by this Commission as collateral damage that is anticipated and, in fact, expected to occur even if the project goes exactly as planned.

FWS, Point Blue, and proponents of the Farallon Island Project refer to these consequences as “not significant,” since mass mortality will not, in most cases, destroy these species' global and/or regional population. We respectfully disagree with this analysis. The project poses significant risks to many species on and around the Farallon Islands, as well as extreme and unnecessary pain and suffering. While aerial application of rodenticides may have at one time been the best available method of removing invasive species from an island, it is no longer the only option and this standard of measure is no longer acceptable. In addition to being dangerous and inhumane, the method is outdated and has proven to be ineffective. The Fish and Wildlife Service, Point Blue, and proponents should not consider the use of toxic, long-lasting rodenticide as a means of rodent eradication without first attempting less invasive methods. A standard of “success” that permits/accepts the death of hundreds of individuals within multiple species targeted for protection must be reconsidered.

THE FARALLON ISLANDS ECOSYSTEM

The Farallon Islands are located in the Gulf of the Farallon Islands Sanctuary—a complex mega diversity hotspot nationally recognized as important breeding and feeding areas and home for at least 25 endangered or threatened species, 36 marine mammal species, including blue, gray, and humpback whales, harbor seals, elephant seals, Pacific white-sided dolphins, over a quarter- million breeding seabirds, and one of the most significant white shark populations on the planet. Positioned within the California Current, along the western edge of the continental shelf where ocean depths drop to around 6,000 feet, the area is one of the world’s four major upwelling regions known to host uniquely productive marine ecosystems driven by a combination of geological features, cold ocean currents, and surface winds. Thus, these distinct features add to the complexity of rodent eradication via a poison drop, which is expected to create secondary harm to a multitude of species.

Nutrients driven to the surface by this process promote growth of organisms at all levels of the ocean food web, including dense phytoplankton forests which support and attract marine broad biota from zooplankton to krill, fish, marine mammals, and other aquatic and semi-aquatic species. These resources sustain an abundance of life from butterflies to bats to a quarter million birds, including many migratory species that flock from as far as Alaska to enjoy the Farallones feast. As such, the danger and potential widespread effects of rodenticide are even more concerning.

The Farallon island arboreal salamander

Adeides lugubris Farallonensis

The Farallon Island Arboreal Salamander (Aneides Lugubris Farallonensis) is a rare subspecies known only to occur on the Farallon Islands. As a lungless amphibian, salamanders breathe through their permeable skin and membranes making them particularly sensitive to chemical contaminants (USGS). The well-being of the Farallon Island Arboreal Salamander is of particular concern considering the essential role amphibians play in the ecosystem, their susceptibility to chemicals and disease, and its indemnity to this single, isolated location (Bralower, T. and Brice, D., n.d.) (Amphibia Web).

Point Blue, in partnership with FWS, has been cataloging and monitoring the Farallon Island Arboreal Salamander since 2006, yet specific data regarding current population size and trends are not found within the FEIS, nor any other published source. Furthermore, no other organization is capable of conducting independent studies, nor confirming Point Blue’s data, on the Farallones. Additionally, in an attempt to reduce rodenticide exposure for resident seabirds (FEIS App. D, pg 3) the project is proposed to take place during the season when this species is considered most active at the surface, and when young, presumably more vulnerable individuals, are known to emerge (FEIS 1.2.2.2, pg 13). 

Citing a recent USDA/APHIS/WS study conducted as a part of the current project proposal, FWS has acknowledged that both dermal and secondary risks of exposure do exist for salamanders. Indeed, many of the salamanders subjected to these experiments experienced sloughing skin, sores, and/or death within 14 days of exposure (FEIS 2.8.12 pg 150) (Witmer, G., 2018). Suggesting that high exposure rates in the laboratory setting were not representative of what salamanders would encounter during an aerial broadcast in the natural environment, FWS insists that the potential for impact to the Farallon Arboreal Salamander population is “not significant” and that no long-term adverse impacts from the eradication operation or the capture/hold program are anticipated (FEIS 4.5.6.1.4, pg. 191, and pg.257).

However, results of these trials (summarized in tables 1 and 2) suggest that risks to salamanders are substantial. While it may be the case that the subjects of this study were exposed to larger concentrations of brodifacoum and diphacinone to illustrate a worst case scenario, we are not convinced that multiple exposures during—and after—project execution will not result in greater suffering and mortality. Even if this is the case, salamanders present for the project will be subject to increased foot traffic by personnel during application as well as ongoing monitoring. Additional contaminants, habitat modification, and increase presence of humans also increase the risk of Batrachochytrium dendrobatidis, a fungal pathogen responsible for extinctions or declines in more than 200 amphibian species globally, but not yet observed on the Farallon Islands perhaps due to its isolation. 

To mitigate admitted uncertainty, FWS plans to capture and house “about 40” individuals to be reintroduced at project completion. The unspecified remainder of the population will be left on the island to be subjected to dermal, as well as secondary, brodifacoum exposure.

Perhaps the availability of population data and trends would shed light on the rationale for such a relaxed approach to protecting this rare, endemic subspecies. Considering their restricted area of distribution due to physiological constraints, known sensitivity to climate change and contaminants, and presumed small population size, one would expect a more specific assessment of this subspecies and the potential impacts of such a hazardous event proposed to take place in its only habitat. To reiterate, the total population size of the species is, apparently, unknown by the only two organizations capable of estimating and protecting it. Therefore, the protection of “about 40” of the rare salamander would risk extinction of the endemic species.

Finally, the FWS insists that the project will benefit the Farallon Islands Arboreal Salamander by removing predation pressure from mice, and by reducing competition for invertebrate prey (FEIS  Section 1.3.4). If this is the case, it is hard to understand why House Mouse management efforts by Point Blue, the sole Farallon partner of FWS, have been so minimal. According to Point Blue’s 2019 Farallon Islands Ecosystem Report (pg.16), trapping sessions have only been conducted in monthly 3-6 day sessions from August until trapping success is less than 10% for two consecutive sessions. Mitigative and/or preventative measures beyond these efforts are never mentioned and appear to be considered unnecessary as further demonstrated by suspension of trapping after March 2019.  This was justified by a lack of need for further monitoring since data from previous years was “sufficient to characterize the annual cycle and interannual differences in overall abundance.” 

Nonetheless, preserving the integrity of the salamander study on the Farallones seems to be of particular interest;

“If possible, individual salamanders will not be collected from under existing research “coverboards” so that this long-term monitoring area can be used to examine potential impacts from the eradication operation and to not impact long-term population studies”

Draft Operations Plan, pg 15 (2021).

Statements such as these, taken together with a failure to effectively reduce, manage, and prevent a rodent infestation on the Farallon Islands over Point Blue’s 50-year tenure suggest that protecting these species, and this ecosystem, are not the primary priority of this organization.  While it appears that Point Blue has conducted meaningful observations and analyses over these years, an unwillingness to share its data, including basic population statistics, is concerning. The current organization and protection of the Farallones by Point Blue in partnership with the Fish and Wildlife Service is ineffective due to the apparent lack of transparency with the public. This lack of transparency and willingness to support rare species on the Farallones through increased scientific knowledge and understanding will overshadow the aftermath of the possible rodenticide drop. 

The Farallon Island Arboreal Salamander is just one example of many species that will certainly be impacted by the project. Marine mammals, birds, invertebrates, and even kelp and algae are susceptible to the detrimental effects of rodenticides on the islands.

Unpublished Data

The use of unpublished data in a project of this magnitude, and potentially devastating, is concerning. Although unpublished data minimizes publication bias and possible unflattering critiques, it is essential that sound science is used and relied upon. The unpublished data referenced throughout the Environmental Impact Report by Point Blue is of extreme importance and should be available to not just the decision makers, the California Coastal Commission, but also the public. The problem here, though, is that the data is not just unpublished, but also undiscoverable—missing in all entirety. 

Point Blue, however, seems unwilling to release their missing data, despite multiple attempts at contacting them. Point Blue’s reluctance to publish these studies, or make them accessible, could be the result of many reasons—none of which are for Defend Them All to evaluate.

The Fish and Wildlife Service’s reliance on unpublished data to support their recommendation of a $1,185,000.00 eradication project on such culturally significant, ecologically important lands is staggering and irresponsible. The use of thirty unpublished, inaccessible studies to support their assertions is most alarming and should be of great concern to the public as the research data’s inaccessibility does not support an open and transparent evaluation. Its use, coupled with the extremely restrictive access to the Farallones, leaves far too much room for erroneous data, and lack of oversight of the project and its outcomes, if the airdrop is permitted to proceed. 

As such, Defend Them All recommends that an independent third-party examine the proposed project, possible alternatives, and the current population status of native and endemic species. If it is determined that the eradication project is the most appropriate response, then a post-project investigation should also be required. The Service, and Point Blue, who control the accessibility of documents regarding the Islands, cannot also be responsible for the evaluation of its success. Without independent review of the island and the project, public trust will not be achieved

Conclusion

Double-crested Cormorant (Nannopterum auritum)

As an organization concerned with the health and well-being of all living things, we stand behind the biodiversity in danger at the Farallon Islands and implore the Coastal Commission to reject the proposed eradication project so that more humane, effective solutions can be explored and implemented. The known and unknown risks of this project are substantial and should not be ignored given the regional importance of this ecosystem and its surrounding waters. 

Furthermore, the Defend Them All Foundation implores the California Coastal Commission to ensure the public is able to reasonably examine all relevant research studies in regards to scientific research and the outcomes of any action taken on the island, in an effort to improve transparency and accountability. Our organization understands the need to protect the Farallons and the beauty and life it beholds, however, to execute a project with implications of this magnitude is irresponsible and must be rejected until reasonable alternatives, research, and transparency are achieved.