“When the Killing’s Done” Maybe never.

I have few opportunities to read fiction because most of my time is spent trying to keep up with rapidly evolving ecological science.  I was grateful for the chance to read the fictional account of island eradications on the Channel Islands because it closely relates to my interest in the planned eradication of mice on the Farallon Islands, which is still pending and as controversial as similar projects on the Channel Islands.  TC Boyle’s book foretells the Farallones project as he sends a member of the fictional project team to the Farallon Islands after completion of the project on the Channel Islands.

When the Killing’s Done by TC Boyle is not entirely fictional. (1)  It is impressively accurate in its description of the eradication projects themselves, but Boyle weaves a tight fictional plot around the key players who implemented the project and those who fought like hell to prevent it from happening.  Like other books by Boyle that I have read, When the Killing’s Done creates intense suspense that moves the reader along at top speed.  His characters are vivid and complex. 

Boyle lives in Montecito, near Santa Barbara, close to the Channel Islands.  No doubt he followed the projects closely as they were debated and resisted by opponents, who were primarily animal rights activists according to Boyle’s account.  In interviews after the publication of the book in 2011, Boyle claimed not to have a personal opinion of the projects:  “I’m not an activist in any way. With certain exceptions, I don’t think politics and art mix very well.”  He sees value in both sides of the debate and the characters in his story have much in common.  The antagonists are vegetarians who value nature and care deeply about the environment and the animals who live in it.  I believe this common ground is also true of the adversaries in the debate about the Farallones project and others like it.

However, the ending of the book suggests that Boyle doubts the ability of humans to control nature.  Although the projects on the Channel Islands were completed to the satisfaction of the land managers–National Park Service and The Nature Conservancy—the final image in Boyle’s story is of animals considered non-native on the Islands making their way to the shore of the Island.  The implication is that maybe the killing is never done and that is the crux of the problem with island eradications in general and the planned mice eradication on the Farallon Islands in particular.

Rat eradication on Anacapa Island

The aerial application of rodenticide to kill rats on Anacapa Island in 2001-2002 was the first of its kind in North America.  The project was also unique because it was complicated by the need to spare a population of endemic native mice on Anacapa.  Over 1,000 native mice were captured before the aerial application of rodenticide and released back on the island after the poison was no longer effective. 

Anacapa Island is the usual success story cited by supporters of the Farallones project where non-native mice are the target for eradication.  Native mice on Anacapa were not considered a threat to birds, but non-native mice on the Farallones are, although there is no evidence that mice actually harm birds on the Farallones either.  The operative word here is “native.”  The mice on the Farallones are targets only because they aren’t native.  The mice on Anacapa undoubtedly eat vegetation too, but that’s not considered a problem so long as they are native.   The mice on Anacapa are probably an important source of food for birds, just as they on the Farallones. 

If mice are not harmful to birds, there is no legitimate reason to poison them, along with untold numbers of non-target animals.  The mice on the Farallones are targets only because they aren’t native. 

Killing of non-target animals

Rodenticides are indiscriminate killers of warm blooded animals, including birds.  An animal who eats rodenticide slowly bleeds to death.  The grisly process of dying takes about 10-20 days.  If poisoned mice are eaten by other animals that animal is also poisoned.  It is therefore inevitable that non-target birds who are predators of mice will be killed by widespread dispersal of rodenticide pellets on the ground that can also be directly eaten by birds and other animals.  This deadly sequence of events has been demonstrated many times by island eradications using rodenticides all over the world and the project on Anacapa Island is no exception. 

Billboard sponsored by Raptors Are The Solution (RATS)

Raptors are the main predators of mice.  Therefore, 63% of raptors on Anacapa Island (37 of 59 individual birds) were captured and either relocated or kept in captivity until the project was done, according to the first study of the project published in 2005. According to that study, “The fate of the remaining birds of prey on the island is unclear. There is evidence that some birds survived the bait application… However, three barn owls, six burrowing owls and an American kestrel either died while in captivity or were found dead on the island. The American kestrel and a burrowing owl that were captured in 2001, after the bait application, likely died from brodifacoum poisoning.” The analysis of the project considers these deaths “negligible.”

A total of 94 seed-eating birds were also found dead after the poison drop.  Most were song birds, but an additional 6 birds were too decomposed to identify the species.  The study notes that these collateral kills were consistent with other similar projects.

Western Gull on Channel Islands. NPS photo

The study makes no mention of gulls that were undoubtedly killed by the project.  Gulls are omnivorous scavengers for whom dead and dying mice are ideal food, preferable to dive bombing for French fries on your picnic table.  According to the National Park Service, “Western gulls are the most abundant breeding seabird in the Channel Islands National Park, with a population estimated at more than 15,000.” Shortly after the poison drop, dead seabirds washed up on the shore near the Santa Barbara harbor.  UC Santa Barbara’s daily newspaper said, “…a strong correlation exists between the National Park Service’s most recent airdrop of pesticide on Anacapa Island and the dead birds.”

In other words, those who implemented the eradication project on Anacapa are probably not telling the full story about the death of non-target birds.  The death of hundreds of gulls is anticipated by the promoters of the project on the Farallones.  If the organization that implements the project is the same organization that monitors and reports on the project (as was the case for the projects on the Channel Islands), we may never know the actual impact on the birds living on the Farallones.

Those who promote these poisonous projects justify the death of non-target birds by saying they are “incidental” and have no lasting impact on the species population.  They will apply for and receive “incidental take permits” in advance of the Farallones project that will satisfy legal requirements of the Migratory Bird Treaty Act and the Endangered Species Act.  The lawsuit that was filed to prevent the Anacapa project was overturned on those grounds.

The killing is never done

Rat eradication on Anacapa and pig eradication on Santa Cruz (where over 5,000 pigs were shot by sharpshooters and 54 Golden Eagles were removed because they were predators of endemic foxes) are the focus of TC Boyle’s masterful book.  Both were implemented and considered successful by the organizations that implemented the projects.  Although land managers are no longer killing animals (to our knowledge) in the Channel Islands they are waging a continuous war on non-native plants by spraying them with herbicide.  When we visited Santa Cruz Island in 2010, we witnessed the application of Garlon on non-native fennel.

Roundup (glyphosate) has been used on the Farallon Islands every year since 1988.  Between 2001-2005, an average of 226 gallons of herbicide were used annually (5.4 gallons per acre per year), according to the annual report of the Farallon National Wildlife Refuge.  Given that these islands are not far from the California coast and are visited by thousands of migratory birds every year, we must expect that the arrival of new plants to the islands will be continuous: seeds are eaten and carried by birds; seeds are carried by birds in their feathers and feet; wind and storms carry seeds to the islands, etc.

The Environmental Protection Agency recently published a Biological Evaluation of glyphosate products.   EPA reports that glyphosate is “likely to adversely affect” 93% of legally protected endangered and threatened plants and animals. That finding applies equally to all plants and animals, whether they are legally protected or not because the physiological processes of species in the same order are similar.

The Environmental Impact Statement for the Farallones project accuses mice of eating vegetation, although far more vegetation is probably killed by herbicides.  Non-native vegetation arrives on the Farallones partly because birds eat it and carry it to the Farallones.  Animals do not care if edible vegetation is native.  Nativism is a human prejudice not shared by animals who seek food and shelter wherever they can find it.

The constant poisoning of plants is perhaps a trivial consideration in comparison to the futility of trying to eradicate mice.  Although rats have been successfully (leaving aside the death of non-target animals) eradicated by some projects, attempts to eradicate mice have been significantly less successful. 

A study of 139 attempted eradications on 107 Mediterranean islands in eight countries, with Greece, Italy, and Spain accounting for the highest number found that eradication projects targeted 13 mammal species. The black rat was the target of over 75% of the known attempted eradications in the Mediterranean Basin; other species targeted were feral goat, house mouse, European rabbit, and domestic cat. The most widely used technique was poisoning (77% of all eradications), followed by trapping (15%) and hunting (4%).  Techniques were largely target-specific.

The average failure rate of the projects was about 11%, but success was defined only as the death of animals living on the islands at the time of the project. However, this percentage varied according to species. The failure rate of house mouse eradication was 75%. Reinvasion occurred after 15% of eradications considered initially successful. 

Farallon Islands, NOAA

The proposed project on the Farallon Islands is a dead end in many ways.  It will kill many non-target animals. It will probably not be successful in the short run or the long run.  Every time it is repeated it will kill more animals. Furthermore, it is pointless because mice do not harm birds on the Farallon islands. 


  • T.C. Boyle, When the Killing’s Done, Viking, 2011.

Restoration or Destruction?

A recent trip to the Channel Islands off the coast of California inspires us to consider the pros and cons of restorations.  Islands are particularly attractive targets for restorations. They often contain endemic species that do not exist anywhere else because they have adapted to unique conditions in isolation.  And the relative isolation of islands implies that once non-native species of plants and animals are eradicated, re-introduction of those species can be prevented.

Santa Cruz Island, Wikimedia Commons

Some of the Channel Islands were inhabited by Native Americans as long as 13,000 years ago.  Ranching by Europeans began on some of the islands in the 1850s. Europeans brought sheep, cattle, pigs, mule deer, and elk to some of the islands.  Five of the eight Channel Islands were designated as a National Park about 30 years ago. 

Restoration began in earnest in the 1990s when ranching operations were ceased and tens of thousands of sheep and cattle were either removed from the islands or destroyed.  Black rats were eradicated from some islands after native mice were herded into protective enclosures so the rats could be poisoned.  Rabbits were eradicated from another island.  We don’t know how that was achieved. 

The next big effort was the eradication of about 6,000 feral pigs. When this was accomplished by sharp shooters, the first unintended consequence of this ambitious restoration was revealed.  It seems that the feral pigs had been the chief diet of a population of Golden Eagles, considered non-native to the Channel Islands.  When the pigs were removed from their menu, they turned to the rare, endemic Channel Island Fox. 

Channel Island Fox, Wikimedia Commons

The population of Channel Island Foxes plummeted.  Those that remained were captured so they could breed in protected conditions while the Golden Eagles were captured and removed to a remote location.  The Channel Island Fox is making a come-back, but the Golden Eagles are apparently gone for good. 

The eagle considered native to the Channel Island, the Bald Eagle, has been reintroduced.  It apparently lives in peace with the Channel Island Fox because it eats fish. 

Mule deer and elk are next up on the eradication agenda for fauna.  Non-native plants are also doomed.  Ice-plant and fennel are the top priorities for eradication by 2011.  Herbicides and prescribed burns are used for this purpose.   

Prescribed burn, Santa Cruz Island, NPS photo

We were surprised to see notice of herbicide application for Garlon 4 Ultra during our visit to this fragile place.  Someone dressed from head to toe in protective clothing was spraying this chemical on a steep hillside.  We have reported the toxic effects of Garlon in our post about herbicides.

This is a complex ecosystem in which simplistic solutions—such as killing all the non-natives—can result in a big mistake.  For example, do we know if there are native Anise Swallowtail Butterflies on the islands that are now dependent upon non-native fennel for their survival?  Do we know how the application of Garlon will impact the survival of the rare, endemic Island Jay?  The US Forest Service found in its risk assessment done for the EPA that the application of Garlon had a significant negative impact on the reproductive success of birds.  Are those who decided to spray Garlon aware of this study?

Herbicide application notice, Santa Cruz Island

We went to the Channel Islands with open minds.  We thought the strongest arguments could be made for restorations on islands.  However, when we learned of the thousands of animals who were sacrificed to this effort and the dangerous and toxic methods used to accomplish the restorations, we were not convinced.  We nearly lost the Channel Island Fox because of the unforeseen consequences of killing feral pigs.  Man would like to believe that he is capable of managing nature.  But can he do so without causing more harm than good?