Western North American Naturalist Volume 78 Number 4 Papers from the 9th California Islands Article 50 Symposium (Part 2) — Issue in Progress

10-22-2018 Yes we can! Exciting progress and prospects for controlling invasives on islands and beyond Daniel Simberloff Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, [email protected]

Brad Keitt Island Conservation, 2100 Delaware Ave., Suite 1, Santa Cruz, CA 95060; Present address: American Bird Conservancy, Box 249, The Plains, VA 20198, [email protected]

David Will Island Conservation, 2100 Delaware Ave., Suite 1, Santa Cruz, CA 95060, [email protected]

Nick Holmes Island Conservation, 2100 Delaware Ave., Suite 1, Santa Cruz, CA 95060, [email protected]

Erin Pickett Island Conservation, 2100 Delaware Ave., Suite 1, Santa Cruz, CA 95060; Present address: Hatfield Marine Science Center, Oregon State University, Newport, OR, [email protected]

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Recommended Citation Simberloff, Daniel; Keitt, Brad; Will, David; Holmes, Nick; Pickett, Erin; and Genovesi, Piero (2018) "Yes we can! Exciting progress and prospects for controlling invasives on islands and beyond," Western North American Naturalist: Vol. 78 : No. 4 , Article 50. Available at: https://scholarsarchive.byu.edu/wnan/vol78/iss4/50

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Western North American Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Yes we can! Exciting progress and prospects for controlling invasives on islands and beyond

Authors Daniel Simberloff, Brad Keitt, David Will, Nick Holmes, Erin Pickett, and Piero Genovesi

This article is available in Western North American Naturalist: https://scholarsarchive.byu.edu/wnan/vol78/iss4/50 Western North American Naturalist 78(4), © 2018, pp. 942–958

Yes we can! Exciting progress and prospects for controlling invasives on islands and beyond

DANIEL SIMBERLOFF 1,* , B RAD KEITT 2,5 , D AVID WILL 2, NICK HOLMES 2, E RIN PICKETT 2,3 , AND PIERO GENOVESI 4

1Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 2Island Conservation, 2100 Delaware Ave., Suite 1, Santa Cruz, CA 95060 3Present address: Hatfield Marine Science Center, Oregon State University, Newport, OR 4Institute for Environmental Protection and Research, Rome, Italy 5Present address: American Bird Conservancy, Box 249, The Plains, VA 20198

ABSTRACT .— Eradication and maintenance management of island invasive species have long histories, and incremental improvements of existing technologies plus occasional novel approaches have led to more challenging targets and increased success rates in certain categories. Many nonnative mammals have been eradicated from islands, as have several nonnative birds, insects, and plants. Hundreds of rat populations have been eliminated, with a success rate over 80%, and islands over 10,000 ha are now feasible targets. Mouse eradication has proven more challenging, but aerial broadcast of anticoagulant toxins has led to increased success. Carnivore eradication—especially of feral housecats and foxes—has been frequently attempted with a recent success rate over 90%. Eradication of herbivores—primarily goats, rabbits, wild boar, and boar/pig hybrids—has been attempted almost 200 times, with a success rate over 90%. Trends in mammal eradication include more frequent attempts and higher success rates on larger islands and inhabited islands, as well as attempts target - ing multiple invasive species. Documented conservation gains from island mammal eradications are numerous. For insects, about two-thirds of some 50 island attempts have succeeded, and most targeted agricultural pests. No summary statistics exist on island plant eradications, but several small infestations have been eradicated. Several insect and plant island invaders have been maintained at low densities by biological control, and plants have been controlled short of eradication by herbicides, often combined with physical or mechanical means. Failures in both eradication and maintenance manage - ment on islands often result from insufficient long-term commitment of resources. Excitement and controversy abound over the prospect that new techniques relying on molecular genetic tools—especially RNA-guided gene drives—may permit eradication or maintenance management of nonnative invaders in situations that have previously appeared extremely difficult or infeasible. Island populations of invertebrates, small mammals, and some plants are particularly propitious targets.

RESUMEN .—La erradicación y la gestión de la conservación de las especies invasoras de islas tienen una larga historia, y la optimización gradual de las tecnologías existentes junto con nuevos enfoques han llevado a objetivos más desafiantes y a un incremento en la tasa de éxito en ciertas categorías. Muchos mamíferos alóctonos han sido erradicados de las islas, al igual que muchas aves, insectos y plantas no nativas. Cientos de poblaciones de ratas han sido eliminadas, con una tasa de éxito superior al 80%, y las islas de más de 10,000 hectáreas se volvieron objetivos viables. La erradicación del ratón, ha representado un mayor reto, sin embargo, el subministro aéreo de toxinas anticoagulantes ha llevado a incrementar el éxito de erradicación. La erradicación de carnívoros, especialmente de gatos domésticos ferales y zorros se ha procurado en reiteradas oca siones, con una tasa de éxito reciente de más del 90%. Por otra parte, la erradicación de herbívoros, principalmente de cabras, conejos, jabalíes e híbridos de jabalí/cerdo, se ha llevada a cabo en alrededor de 200 ocasiones, con una tasa de éxito superior al 90%. Las tendencias en la erradicación de mamíferos incluyen acciones más frecuentes y mayor tasa de éxito en las islas de mayor tamaño y en islas habitadas, así como, acciones teniendo como objetivo múltiples especies invasoras. Los beneficios de la erradicación de mamíferos isleños son numerosos. En cuanto a los insectos, aproximadamente dos tercios de las 50 ten - tativas de erradicación en islas tuvieron éxito, la mayoría de plagas agrícolas. No existen informes estadísticos sobre la erradicación de las plantas de las islas, pero se han logrado erradicar varias infestaciones pequeñas. Muchos insectos y plantas invasoras se han mantenido en bajas densidades por medio de control biológico, las plantas han sido controladas con herbici - das, frecuentemente combinando con el uso de medios físicos o mecánicos, sin necesidad de erradicarlas. Las fallas tanto en la erradicación como en la gestión de la conservación, con frecuencia, son resultado de una asignación de recursos insuficientes a largo plazo. La posibilidad de que nuevas técnicas basadas en herramientas genéticas moleculares (especialmente las unidades de genes guiadas por ARN) permitan la erradicación o la gestión de la conservación de especies invasoras, en situa - ciones que anteriormente parecían extremadamente difíciles o inviables, generan una gran conmoción y controversia. Las poblaciones insulares de invertebrados, pequeños mamíferos y algunas plantas son objetivos particularmente propicios.

*Corresponding author: [email protected] DS  orcid.org/0000-0002-1424-9291

942 SIMBERLOFF ET AL . ♦ PROGRESS IN CONTROLLING ISLAND INVASIONS 943

Realization that introduced species could inveighed against eradication programs for damage native species and ecosystems came introduced insects in favor of biological control. late. Early naturalist-explorers who worked to Dahlsten (1986) and other skeptics were establish the broad biogeography of the earth likely influenced by several costly, high-profile and who recognized that some species were failed continental eradication attempts that not native to some sites they inhabited simply inflicted enormous nontarget impacts, partic - noted the presence of those species (Sim - ularly projects in the United States aimed at berloff 2013a). Probably the first to note a the gypsy moth (Spear 2005) in the 19th cen - huge impact on islands was Joseph Hooker, tury and the red imported fire ant (Buhs 2004) who lamented the devastation of several island and white pine blister rust (Maloy 1997) in the floras by introduced livestock and European 20th century. However, even before the SCOPE plants (Hooker 1867). Alfred Russell Wallace project, successful programs had both eradi - raised the same concern about Saint Helena cated some introduced populations and main - (Wallace 1880). In the early 20th century, still tained others at less damaging levels, and well before the impacts of nonnative species islands featured prominently in such efforts. were widely seen as a concern, James D. The SCOPE participants seemed not as aware Ritchie (1920) described the impact of intro - of many of these successes as they might have duced species, particularly in Scotland, but he been, perhaps because they were largely acad - also deplored, in less detail, impacts on other emics focused on ecology and conservation islands such as Mauritius. Contemporarily, rather than scientists focused on managing George M. Thomson (1922) described impacts specific problems related primarily to agricul - of introduced species on the native flora and ture and public health. Probably the earliest fauna of New Zealand. Charles Elton (1958), insect eradication was the elimination from in his popular book The Ecology of Invasions the island of Pr íncipe of a long-established by Animals and Plants, featured ecological population of tsetse fly, Glossina sp., between impacts of invaders on the Hawaiian Islands, 1911 and 1914; a reinvasion in 1956 was also New Zealand, Tristan da Cunha, Easter eradicated (Lapeyssonie 1988). Between 1934 Island, and other islands. Elton’s book did not and 1937, the citrus blackfly ( Aleurocanthus trigger the burgeoning research that consti - woglumi ) was eradicated from a several-block tutes modern invasion biology. Rather, this area of Key West (Hoelmer and Grace 1989). field exploded in the wake of a 1980s project The New World screwworm fly ( Cochliomyia convened by SCOPE (Scientific Committee hominivorax ) was eradicated during 1954/1955 on Problems of the Environment, an arm of on the island of Curaçao through use of the the International Council of Scientific Unions) revolutionary sterile-male technique (Baum - under the leadership of Harold Mooney (Sim - hover et al. 1955), which subsequently found berloff 2011a). Many SCOPE participants wide application both on islands and the recalled having read Elton’s book, and the mainland. The recently compiled Database of impact of invasions on islands has been a major Island Invasive Species Eradications (DIISE; component of the field ever since (Simberloff Keitt et al. 2011, DIISE Partners 2014), a 2011b). project that aims to tabulate all island-wide Improved control of invasives was one of vertebrate eradication attempts and their out - the SCOPE project’s 3 goals (Simberloff 2011a), comes, identifies many eradications of intro - but this turned out not to be a major focus of duced mammals from entire islands before publications resulting from the project. The the SCOPE project. For instance, the Norway emphasis was instead on the other 2 goals: rat ( Rattus norvegicus ) was eradicated from determining why certain species seem particu - Flatey in 1971 (Petersen 1979), the domestic larly invasive and why certain sites, such as cat from Aride Island in 1932 (Watson et al. islands, appear to be more readily invaded. 1992), and goats from Ascension Island soon For example, the synthesis SCOPE volume after World War II (Ashmole et al. 1994). In (Drake et al. 1989) contained 22 chapters, of fact, before 1970 there were at least 5 whole- which only 4 treated management. The widely island eradications of rats, 6 of cats, 26 of read North American volume (Mooney and goats, 14 of rabbits, and 16 of boar, feral pigs, Drake 1986) contained only one chapter (of and their hybrids. Thus, in retrospect, the 16) on management, in which Dahlsten (1986) pessimism among conservationists regarding 944 WESTERN NORTH AMERICAN NATURALIST (2018), V OL . 78 N O. 4, P AGES 942 –958 eradication in the wake of the SCOPE project Major efforts to reduce nontarget impacts of was overblown. herbicides and pesticides have been a promi - Pessimism about eradication has sometimes nent feature of maintenance management led to the view that, if eradication fails, the since Silent Spring, with some success, but battle against an invader is lost (e.g., Vince problems persist and efforts continue (DiTo - 2011). However, invaders can sometimes be maso 2011, Herms and McCullough 2011, maintained at low enough levels to minimize Whisson 2011, Yadav and Singh 2011). Several ecological damage. The 3 major approaches early biological control introductions on islands to maintenance management are mechanical had nearly legendary nontarget impacts. or physical control, chemical control, and These include introduction of the small Indian biological control (Clout and Williams 2009, mongoose to islands worldwide (Barun et al. Simberloff 2013b). On continents, several 2011), the cane toad ( Rhinella marina ) to Aus - invasive plants and animals have been main - tralia (Lever 2001), the rosy wolfsnail ( Euglan - tained at low levels for extended periods by dina rosea ) to many Pacific islands (Civeyrel hand and/or machine, sometimes in combina - and Simberloff 1996), and the cactus moth tion with chemical control, but there do not (Cactoblastis cactorum ) to Nevis (Pemberton appear to be successful island examples, despite and Liu 2007). These cases were key stimuli some massive efforts. For example, between for advances in biological control technolo - 1902 and 1908 on Trinidad, 30,895 individuals gies, including greater target selectivity (Van of the small Indian mongoose ( Herpestes Driesche et al. 2008, 2016). auropunctatus ) were removed by trapping and In sum, during the SCOPE project and in hunting in an aggressive bounty program; the the succeeding decade, invasion scientists were same program yielded 142,324 individuals largely pessimistic about the prospects for between 1927 and 1930, with no detectable eradicating invaders on islands or continents, population impact (Urich 1931). In light of the perhaps unjustifiably. Similarly, acceptable difficulties of island-wide eradication on large means of long-term mainenance management islands, a number of projects now entail of invasions seemed a difficult goal, largely “mainland islands,” areas (often large ones) from because of nontarget impacts and expense. which all of one or more target invaders are Nevertheless, many workers continued to try removed, with reinvasion precluded by fenc - to achieve eradication or at least long-term ing. Perhaps most striking among several such control by a plethora of venerable techniques, projects in New Zealand is Maungatautari, a many modifications of these, and several new mountain and surrounding area of 3400 ha on approaches, especially in attempts to manage the North Island from which 14 nonnative introduced mammals on islands. Below we mammals were removed; only the house mouse describe attempts to eradicate various taxa (Mus musculus ) persists (Innes and Saunders on islands, as well as various maintenance 2011). In the Hawaiian Islands, the goal of management efforts. island-wide control of feral pigs has been abandoned in favor of control within several ERADICATION large fenced areas in which the goal is Mammals removal followed by sustained monitoring with zero detections (T. Menard, personal A scan in early 2014 of the DIISE database communication, 2017). yielded 1086 a mammal eradication attempts It was many pre-SCOPE continental exam - on 693 islands targeting 6 rodent species, 12 ples of nontarget impacts of attempted long- herbivore species, and 13 carnivore species. term control by chemicals (sometimes as a sort Of these, 125 projects targeted more than one of consolation prize for a failed eradication species, and we tallied an attempt on each attempt) and one island example (DDT impact species as a separate attempt. Of these 1086 on cutthroat trout [ Oncorhynchus clarkii ] on attempts, 924 (85%) succeeded, with a dramatic Vancouver Island in 1957) that inspired recent increase in frequency of eradication Rachel Carson’s Silent Spring (Carson 1962). attempts: 67% occurred after 1995. The aData were accessed in April 2014 and included events with data quality classified as good or satisfactory, and status as failed, successful, or successful-reinvaded. We included only whole-island eradications for mammals but whole-island and restricted- range events for birds. SIMBERLOFF ET AL . ♦ PROGRESS IN CONTROLLING ISLAND INVASIONS 945 increase is driven particularly by a surge in eradication efforts that targeted mice using the number of rat eradication attempts and a aerial broadcast of anticoagulant toxins have proportionally similar (but numerically much succeeded, including the successful 2011 smaller) increase in the number of mouse effort on 12,800-ha Macquarie Island, the eradication attempts. The recent (defined as largest island from which the house mouse, or post-1995) success rate, 84%, does not differ any rodent, has been eradicated. All 11 mouse significantly from the overall rate. However, eradication attempts in the current decade substantial differences exist among the over - have succeeded, an increase over the rate of all success rates of the different groups and 64% before this decade. Most of the 78 in how these success rates have changed attempts (95%) have been on islands smaller through time. than 1000 ha. Feasibility studies for mouse For rodents, 617 attempts targeted one of eradication have been completed for much 5 rat species, and several projects included larger islands, such as Gough Island (Parkes attempts to eradicate more than one species. 2008) and Marion Island (https://www.birdlife The other targeted rodent (78 attempts) was .org.za/conservation/seabird-conservation/ the house mouse ( Mus musculus ). For rats, marion-island-appeal, accessed 25 September all but 3 of the 617 eradication attempts on 2017). 478 islands targeted the Norway rat ( Rattus For carnivores, 88 of 175 attempts on 146 norvegicus ), black rat ( Rattus rattus ), or Pacific islands targeted the house cat ( Felis domesti - rat ( Rattus exulans ). Few attempts occurred cus ), while another 31 targeted one of 3 fox before the 1980s, which saw a sharp increase species. Several successful eradications of in the number of successful attempts per carnivores occurred before a sharp increase in decade; 76% of rat eradication attempts have attempts in the 1980s, and successes are most occurred after 1995. The greatest number common on larger islands, between 100 and have been on small islands—45% on islands 10,000 ha. The largest island to date on which smaller than 100 ha. But the number of suc - a carnivore has been eradicated is 102,560-ha cesses on large islands has increased substan - Hiiumaa, Estonia, where an American mink tially, with the largest successful eradications (Neovison vison ) eradication ended in 1999 so far being those of the black rat on 12,800-ha (Macdonald and Harrington 2003). Eradica - Macquarie Island, Australia (Beavis and Junt tions targeting American mink, whose range 2014), and the Norway rat on 11,330-ha is mostly restricted to riparian areas, are Campbell Island, New Zealand (Towns and among the larger-scale carnivore eradication Broome 2003). It is noteworthy that, since attempts; a mink eradication attempt is in 2014, operations have been completed to progress on ~217,000-ha Lewis and Harris, remove Norway rats and house mice from Scotland (Scottish Natural Heritage 2013). South Georgia Island in the Atlantic. This The next large-scale carnivore eradication was project included 9 separate treatment areas removal of arctic foxes ( Vulpes lagopus ) from (continuous bays and peninsulas separated by 90,500-ha Attu, Alaska (Thomson and Ebbert glaciers; mice were in only one treatment 2005). For carnivores, the success rate increased area), the largest of which is 30,822 ha. The with the sharp increase in number of attempts next stage is to determine whether success in the 1980s, with a success rate before the has been achieved (South Georgia Heritage 1980s of 59% and a subsequent rate of 92%. The Trust 2016). Overall, the success rate for overall success rate for carnivore eradications island rat eradications has been 84% ( n = has been 87%; post-1995 the success rate has 617). Success rates on tropical islands are been 92%; through 1995 it was 81% ( n = 101). substantially lower than on other islands The main targeted herbivores have been (Russell and Holmes 2015). the goat ( Capra hircus ), European rabbit For the house mouse, 69% of the 78 (Oryctolagus cuniculus ), and wild boar or pig attempts on 68 islands succeeded, and as with (Sus scrofa ), with 74, 64, and 19 attempts, rats, few attempts preceded 1980. Operations respectively, of 193 total for 12 species on 143 in some of these 78 eradication attempts also islands. The first such attempt was probably targeted Rattus species, and several of these the eradication of feral pigs on Bermuda in attempts were not designed specifically to 1630 (but note that we did not include this target mice. Since 2005, all but one of the 16 case in our analysis because it did not meet 946 WESTERN NORTH AMERICAN NATURALIST (2018), V OL . 78 N O. 4, P AGES 942 –958

DIISE data-quality standards). A major targeted only 2 or 3 rat species. However, 35 increase in attempts began in the 1950s. For of the projects targeting rats also targeted herbivores, the success rate has been consis - mice, and 45 of them targeted other mammals tently high (94% overall, 95% post-1995 [ n = or a bird. Multispecies eradication projects 87 ]), and although more attempts have been tended to be on smaller islands, averaging made on islands between 100 and 1000 ha, 1334 ha compared to 3501 ha for average island many attempts have been made on much larger size in single-target eradication attempts. islands, particularly in the last 2 decades. The Oppel et al. (2011) and Glen et al. (2013) largest island on which an herbivore was have reviewed challenges and outcomes of successfully eradicated is Santiago (58,465 ha) eradication attempts on inhabited islands. In in the Galápagos Islands, Ecuador, where pigs our analysis we define an inhabited island as were eliminated by 2000 (Cruz et al. 2005). one either permanently or seasonally inhab - Even larger islands have had successful erad - ited by humans who stay overnight, as deter - ications of invasions that were not island- mined by a literature review, Wikipedia, and wide—for example, Cyprus ( ~925,000 ha), Google Earth satellite imagery depicting from which wild boar were eliminated by 2004 buildings. A total of 194 eradication attempts (Hadjisterkotis and Heise-Pavlov 2006), and have been mounted on 94 inhabited islands Isabela in the Galápagos Islands (458,812 ha), (as previously, a multispecies project on an where goats were eliminated from the entire inhabited island is counted multiple times, northern part of the island ( ~250,000 ha) in an once for each species). Of these 194 attempts, attempt ending in 2006 (Carrion et al. 2011). 64 were part of 24 multispecies projects on In the California Channel Islands, aside from 22 islands; 86% of these multispecies projects goats, rabbits, and boar, successful eradica - on inhabited islands were undertaken after tions have removed sheep, mule deer, elk, 1990. For carnivores, herbivores, and birds donkeys, cattle, and horses from various the numbers of eradication attempts on inhab - islands (CDFW 2015). ited islands are 47, 59, and 10, respectively. INCREASING COMPLEXITY OF MAMMAL Seventy-eight targeted rodents, of which 65 ERADICATIONS .—Not only have the number of targeted rats. Through the 1970s, the propor - mammal eradication attempts and frequency tion of eradication attempts on inhabited of success increased, but the scope and com - islands was 27%; since then it has fallen to plexity of the projects have increased. We 17% of the 1086 total attempts. However, consider an attempt part of a multispecies because 91% of all eradication attempts were eradication project if more than one species post-1980, this is when the greatest number of was targeted within a 2-year period on the same attempts on inhabited islands has occurred. island. Of the 1086 eradication attempts ana - There was a sharp uptick in the number of lyzed, 292 were parts of 125 multispecies proj- attempted eradications on inhabited islands ects on 120 islands. Of these multispecies in 1960 for all species except for rodents, and projects, 119 succeeded in eliminating at least in 1990 there was also an uptick for rodents. one target and 102 eliminated all targeted Average area of targeted inhabited islands was species. Thus, 221 multispecies eradication 11,508 ha, whereas average area of targeted projects were partially or completely successful. uninhabited islands was only 748 ha. Twenty-nine of these multispecies projects Birds targeted more than 2 species, and one project (on Rangitoto and Motutapu, New Zealand) Our analysis showed that 8 species of birds eradicated all 8 targeted species (Griffiths et have been eradicated in 23 attempts on 21 al. 2012). Multispecies projects were relatively islands (14 since 1995), with a success rate of uncommon through the 1960s but became 83%. The Weka ( Gallirallus australis ) or Com - much more frequent beginning in the 1970s. mon Myna ( Acridotheres tristis ) were targeted At least 20% of all eradication attempts in in 68% of the successes. Ten of the successes every decade from the 1970s onward were were on islands <100 ha, but 5 have been on parts of multispecies projects, and 109 such islands >10,000 ha; the largest was the Span - projects have been mounted since 1990. One ish Balearic island Menorca ( ~70,000 ha), or more rat species were targets of 104 of these where the Ruddy Duck ( Oxyura jamaicensis ) multispecies projects—indeed, 39 of them was eradicated from riparian habitats in 2001 SIMBERLOFF ET AL . ♦ PROGRESS IN CONTROLLING ISLAND INVASIONS 947

(Genovesi and Carnevali 2011). Notable suc - Invasives (Veitch and Clout 2002) reported 59 cesses since 2014, when our statistical analysis attempts against animals and only 14 against ended, include the largest whole-island eradi - plants, while the successor conference in 2010 cations for flying birds: the Red-whiskered (Veitch et al. 2011) described 129 attempts Bulbul ( Pycnonotus jocosus ) from ~1100-ha against animals and 8 against plants. Rejmánek Assumption Island, Seychelles (Anonymous and Pitcairn (2002) were pessimistic about 2015), and the Wild Turkey ( Meleagris gal - the possiblity of eradicating terrestrial plants lopavo ) from 25,000-ha Santa Cruz Island, unless the target area was extremely small, California (Morrison et al. 2016). primarily because of soil seed banks and the expense of monitoring and treating large areas. Insects Nevertheless, invasive plants have occasion - No analog to DIISE exists for insect ally been eradicated from islands, usually eradications, but the Global Eradication and small ones (Simberloff 2013c). Rejmánek and Response Database (GERDA) for arthropod Pitcairn (2002) describe 2 eradications of pests and pathogens (Tobin et al. 2014, Kean small infestations in the California Channel et al. 2017) tabulates 970 attempts against 308 Islands. Cory and Knapp (2014) and J. Knapp taxa, of which 165 targeted arthropods. Of (personal communication 2016) report 32 inva - these, 54 attempts targeted 16 arthropod sive plant species targeted for eradication on species on 47 islands. Of 46 known outcomes, Santa Cruz Island, with approximately 1000 32 succeeded. Most of these attempts targeted populations treated, three-fourths apparently fly pests of agriculture, but others served successfully, and at least 3 species likely eradi - conservation, such as eradication of the honey cated in the ongoing project. A program to bee ( Apis mellifera ) from Santa Cruz Island eradicate 29 invasive plant species from Raoul in the California Channel Islands (Wenner et Island, New Zealand, has succeeded for 11 al. 2009) and the little fire ant ( Wasmannia species that infested small areas, while progress auropunctata ) from Santa Fe Island in the on the 7 main targets, all widespread, has Galápagos Islands (Wetterer and Porter 2003). been gradual, largely because of the plants’ A partially overlapping data set tabulating biology and the difficult terrain (West and 316 ant eradication attempts (Hoffmann et al. Thompson 2013). A heavy infestation of 2016) lists 70 attempts on 20 islands, of which Cenchrus echinatus (Poaceae) was eradicated half succeeded. The great majority of successes from 64 ha on Laysan Island (Flint and were on very small islands or small sections of Rehkemper 2002). A prominent claim that a larger islands, but larger successes are noted, large-scale plant eradication project in the including the likely eradication of the Argentine Galápagos Archipelago was a costly failure, ant ( Linepithema humile ) from approximately with only 4 small infestations of 30 targeted 400 ha on Santa Cruz Island in 2013–2014, populations actually removed (Gardener et al. facilitated by a newly formulated bait (Boser 2010), was recently rebutted with data show - et al. 2014, 2016). As with vertebrate eradica - ing that eradication was the goal in only 21 of tions, recent progress has been incremental. the attempts, that 8 attempts had succeeded, There has not been a transformative approach and that several others would have succeeded since the development of the sterile insect and still could with greater but still feasible technique (SIT) in the 1950s (Klassen and commitment of resources (Buddenhagen and Curtis 2005). Most successes have used chemi - Tye 2015). cals, SIT, or both, although the honey bee Many authors have noted that a key to eradication first used chemicals to destroy success is long-term commitment of resources many colonies and then employed introduced to an attempt and that the failure of several parasitic varroa mites, achieving an unusual attempts likely arose from absence of such eradication by a biological control agent. commitment. For plants, the existence of persistent soil seed banks particularly necessi - Plants tates long-term commitment. Herbicides and Eradication of invasive plants on both hand-pulling have been almost universally islands and mainland has lagged behind that employed in island invasive plant eradication of animals. For example, the proceedings of attempts, both those that have succeeded and the 2001 Conference on Eradication of Island those that have not. 948 WESTERN NORTH AMERICAN NATURALIST (2018), V OL . 78 N O. 4, P AGES 942 –958

Other Taxa of the mink from 60 islands and islets of Finland (Nordström et al. 2002) and the increased A smattering of attempts have been made to breeding success of several tern species ( Sterna eradicate other taxa from entire islands but paradisaea , S. hirundo , S. albifrons ) following there are too few to summarize success rates eradication of the same predator in the Outer and to seek patterns. For snakes, we found only Hebrides (Roy 2011). Eradication of feral cats the failed attempt to eradicate the wolf snake (Felis catus ) from North West Island, Australia, (Lycodon aulicus ) from the small Île aux spurred a population increase in the Buff- Aigrettes off the coast of Mauritius (Rodda et banded Rail ( Gallirallus philippensis ) and the al. 2002). Ongoing attempts to eradicate the Silver-eye ( Zosterops lateralis ) (Dickman 1996). brown tree snake ( Boiga irregularis ) from a In Asuncion and San Roque Islands, Mexico, small fenced area of Guam have failed so far. populations of Cassin’s Auklets ( Ptychoramphus Kraus (2009) reports that the Australian frog aleuticus ) were extirpated by cat predation Limnodynastes dumerilii was eradicated from (Wolf et al. 2006), but this species recolonized a small region of the North Island of New the island after cats were eradicated (Félix- Zealand before further spread, and also that Lizárraga et al. 2009). Eradication of cats on the toad Bufo gargarizans was eradicated from Natividad Island, Mexico, has dramatically a small site in Okinawa before it dispersed lowered breeding season mortality of the further. Bullfrogs ( Lithobates catesbeianus ) were Black-vented Shearwater ( Puffinus opisthome - eradicated from several ponds in southern En- las ) (Keitt and Tershy 2003). Removal of Golden gland (Kraus 2009), and they do not currently Eagles ( Aquila chrysaetos ) from the northern occur in the wild in Great Britain. The coqui Channel Islands and eradication of the pigs (Eleutherodactylus coqui ) was eradicated from a on Santa Cruz Island that were subsidizing small area on Oahu before it spread on the the eagles have spurred recovery of the island island (Beachy et al. 2011), and incursions are fox, Urocyon littoralis (Coonan et al. 2010). Rat suppressed elsewhere in Hawaii (http://www eradication on Anacapa Island led to increased .kauaiisc.org/coqui, accessed 26 September abundances of seabirds and marine intertidal 2017). Nico and Walsh (2011) reviewed several invertebrates, as well as 2 seabird species that attempts (including a few successes) to eradi - had likely been extirpated by the rats (Ashy cate freshwater fishes from various sites on Storm-Petrel [ Oceanodroma homochroa ] and Pacific islands. Massive attempts to eradicate Cassin’s Auklet) now breeding on the island nonnative crayfish from particular rivers in (Newton et al. 2016). Great Britain have proven futile (Holdich and One of many examples of positive outcomes Pöckl 2007), but a small established population of removing an herbivore (in this instance, an of the Australian hairy marron crayfish ( Cherax omnivorous one) is the eradication in 1958 of tenuimanus ) was eradicated in New Zealand pigs from Clipperton Island (Pacific Ocean) in (Yaldwyn and Webber 2011). New invasions of response to drastic population declines of sev - the giant African snail ( Lissachatina fulica ) have eral bird species. Seabird populations recov - been eradicated from 2 small Pacific islands, as ered significantly (Lorvelec and Pascal 2005). has a new infestation of the freshwater snail Eradication of rabbits has aided recovery of Pila conica in Palau (Cowie 2011). certain native plant species on Round Island, Benefits of Island Eradications Mauritius (North et al. 1994), and Île Verte and Île Guillou in the Kerguelens (Chapuis et al. Eradications of invasive mammals on islands 2004), but in both instances other native plant have yielded enormous conservation returns. populations fell because populations of intro - A sample of 251 eradications on 181 islands duced plants that had been favored by rabbits revealed that 596 populations of 236 native increased. A similar result has occurred in the island species have benefited (Jones et al. wake of goat eradication on several islands 2016). Eradication of the American mink from (Campbell and Donlan 2005). Hiiumaa Island, Estonia, was essential to reintro ducing the endangered European mink MAINTENANCE MANAGEMENT (Mustela lutreola ). Many other cases exemplify positive effects of eradicating American mink, Eradication is tempting because, if it suc - including increases in breeding densities of ceeds and reinvasion does not occur, manage - several waterfowl species following removal ment costs for the target species disappear, SIMBERLOFF ET AL . ♦ PROGRESS IN CONTROLLING ISLAND INVASIONS 949 except for those associated with preventing the introduced South American cactus moth reinvasion. Eradication is particularly seduc - Cactoblastis cactorum (Dodd 1940), but using tive on islands because of their smaller size this species against Opuntia on other islands relative to the mainland, suggesting greater has led to 2 major controversies (Hoddle 2016) feasibility, and relative isolation, which should relevant to employing biological control in greatly reduce the probability of rapid reinva - general. This moth successfully controlled sion. Maintenance management, on the other Opuntia after it was introduced to the Carib - hand, aims not to eradicate a target pest but to bean island of Nevis (and quickly reached maintain it at acceptable levels. Classical bio - nearby St. Kitts) in 1957 (Pemberton and Liu logical control, among the 3 common technolo - 2007), but the target species were native gies, appears attractive from a cost perspective rather than introduced. Second, the moth has because, even though development costs may spread to Florida either on its own or perhaps be high (particularly now that nontarget impacts assisted by hitchhiking on cut flowers, and are recognized as a concern), in principle if the from Florida it has spread northward and project works, no further expenses accrue. The westward, threatening native Opuntia species target pest is never extirpated, and if its popu - in North America. The cactus moth has also lation increases, it is automatically controlled controlled 2 nonnative Opuntia species on by an increase in the population of its intro - Mauritius (Fowler et al. 2000). The key lesson duced natural enemy. Most applications have from these campaigns is to be mindful of the involved agricultural pests, but the technology possibility of spread of a control agent to unin - is increasingly used for conservation purposes tended regions. A disturbing element in the (Van Driesche et al. 2016). discussion of possible nontarget impacts of A few examples exist of successful biological biological control is the frequent unstated control of invasive insects on islands with no assumption (e.g., Hoddle 2016) that if an evidence of substantial nontarget impact. The introduced natural enemy does not completely cottony cushion scale (Icerya purchasi ), which eliminate some native species, it is harmless. threatened many native plants after its arrival In fact, society recognizes many impacts far in the Galápagos Islands in 1982, has been short of extinction as environmental “harm” successfully controlled by the lady beetle (Simberloff 2005). It is important to realize Rodolia cardinalis, introduced from 2002 to also that many biocontrol programs for inva - 2005 (Causton et al. 2016). The endemic coral sive plants on islands fail, and that a consistent tree ( Erythrina sandwicensis ) of Hawaii, a complaint of invasive plant managers (e.g., major component of dwindling dry forest, Fowler et al. 2000, Loope et al. 2013) is inade - was rescued from devastating attack by an quate funding for biocontrol programs. introduced gall wasp ( Quadrastichus erythrinae ) Physical and mechanical methods, either by quick testing and release of the parasitic alone or together with herbicides, have often wasp Eurytoma erythrinae (Kaufman and successfully managed invasive plants on islands. Messing 2016). Introduction of the lady beetle The invasive N-fixing tree albizia ( Falcataria Hyperaspis pantherina rapidly controlled the moluccana ) was well controlled by girdling on South and Central American scale insect Tutuila, American Samoa (Hughes et al. 2012) Orthezia insignis, which had threatened the and Silhouette in the Seychelles (Rocamora endemic national tree of Saint Helena, Com - and Henriette 2017). In the Galápagos Islands, midendrum robustum (Cock 2003). introduced trees Cedrela odorata and Cin - Introduced natural enemies have also con - chona pubescens were maintained at levels trolled environmentally damaging invasive below the threshold of impact by a combina - plants on islands, for example Cordia curas - tion of physical and chemical means (Gardener savica on Mauritius (Fowler et al. 2000) and et al. 2013). Herbicides have locally controlled mistflower ( Ageritina riparia ) on North Island, many invasive plant species on the island of New Zealand (Suckling 2013). On Tahiti, an Hawaii (Loope et al. 2013). Effectiveness and introduced fungus has partially controlled nontarget impacts of physical/chemical man - the massive invasion by Miconia calvescens agement of the same plant species vary (Loope et al. 2013). The most famous example among islands, and both successes and fail - for both islands and continents is control of ures abound. Often mobilization of sufficient New World Opuntia species in Australia by person power and maintenance of an adequate 950 WESTERN NORTH AMERICAN NATURALIST (2018), V OL . 78 N O. 4, P AGES 942 –958 budget are critical. Aside from concern with 2012) to permit eradications that had previ - nontarget impacts, expense and the evolution of ously been intractable. A trained dog on Raoul resistance are frequent issues with herbicides. Island finds infestations that have proven dif - Many publications detail specific methods and ficult for project staff to access and to detect limitations (e.g., Sarat et al. 2015, Rocamora (Havell 2014). In other invasive plant man - and Henriette 2017). agement programs, dogs have proven more Long-term maintenance management is effective than humans at locating targets often viewed as a second-best alternative (e.g., Goodwin et al. 2010). Dogs have been when eradication fails. However, it is worth crucial in other eradication projects, such as noting that many successful maintenance the long, successful effort to clear Macquarie management programs, especially those using Island of all nonnative mammals (Beavis and physical, mechanical, and chemical means, Junt 2014), and experiments have suggested were originally planned as eradication attempts. that dogs can be useful parts of island proj - It should also be borne in mind that either ects to manage or eradicate the small Indian incremental or transformative technological mongoose (Fukuhara et al. 2010) and the brown advances might enable what had been a main - tree snake, Boiga irregularis (Savidge et al. tenance management campaign to achieve 2011). Ongoing monitoring for the Argentine complete eradication. This fact, combined ant eradication attempt on Santa Cruz Island with the prospect that lack of management employed a dog in 2017 (C.L. Boser, personal may lead to degradation so severe that restora - communication, 2017). tion becomes extremely difficult (Corbin and Novel methods might be profitably D’Antonio 2012), or even impossible when employed in maintenance management. In extinctions occur, should give pause when particular, endocrine mimics and disrupters maintenance management is perceived as too appear to have been used very rarely for costly. environmental or conservation purposes, even though they have an extensive history in TECHNICAL IMPROVEMENTS AND PROSPECTS managing invasive agricultural and forest insect pests (Reddy and Guerrero 2010), and The increasing success of mammal eradi - sex and migratory pheromones are in develop - cations has entailed incremental improve - ment for managing the invasive sea lamprey ments of varying degrees to well-established (Petromyzon marinus ) in the Great Lakes approaches, such as aerial broadcast of exist - (Sorensen and Bergstedt 2011). Several of ing anticoagulant toxins. Sometimes the incre - the innovative technologies that Campbell et ment allows major scaling up of an eradication al. (2015) list in their horizon scan of promis - attempt to improve its efficacy. One example ing approaches for rodent eradication could is sterilization and hormone implants to induce also be cost effective and useful for mainte - prolonged estrus in female Judas goats (Camp - nance management, such as virus-vectored bell et al. 2007), an approach that played a key immunocontraception and crab deterrents in role in goat eradication on the northern part of toxic baits. Isabela Island (Carrion et al. 2011). Addition - Sixty years of intensive use of synthetic ally, Campbell et al. (2015) identified several insecticides have been marked by substantial approaches in various stages of development ongoing improvement in terms of new chemi - that could transform rodent eradication. cals and lower-dose formulations, lower prob - For island plant eradication, several novel ability of nontarget impacts, better delivery to techniques, some previously applied in eradi - targets, and increased attention to lowering cation programs for mammals, constitute persistence and long-term direct and indirect advances that could profitably be more widely effects of sublethal concentrations on nontarget employed. The use of helicopters to locate and species and entire communities (Guedes et al. eradicate plant populations in inaccessible or 2016). Nevertheless, substantial nontarget difficult-to-reach locations has been crucial to problems remain (e.g., Kerr 2017). Similarly, the Santa Cruz Island project (Knapp et al. biological control has undergone substantial 2012, Cory and Knapp 2014). On Santa Cruz improvement in its focus on minimizing likeli - Island, helicopters have also been used with hood of nontarget impacts and increasing herbicide ballistic technology (Leary et al. probability of substantial control of the target SIMBERLOFF ET AL . ♦ PROGRESS IN CONTROLLING ISLAND INVASIONS 951

(Van Driesche et al. 2016), although room 2017). An attraction of gene-silencing is that for improvement remains on both counts the technique targets specific genes, so it is (Williamson and Fitter 1996, Simberloff 2012a, not only highly species-specific but could Cock et al. 2016). Biological control projects even differentiate between an introduced have also now moved beyond focus only on genotype and a native genotype. Further - direct killing of the target pest. For example, more, it could be used even on species repro - on Christmas Island, the devastating attack by ducing asexually. yellow crazy ants ( Anoplolepis gracilipes ) on The first high-profile case involving a heri - the iconic red crab ( Gecarcoidea natalis ) was table change was that of the genetically mod - stemmed at great expense by periodic heli - ified Aedes aegypti mosquito produced by copter spraying with fipronil (Green and Oxitec, a British company, to combat dengue O’Dowd 2009). The ant invasion had been and released in field trials on Grand Cayman precipitated by introduction of a nonnative Island in 2009 (Enserink 2010). Even before scale insect whose honeydew was exploited the release, the prospect had elicited concern by the ants, and a new biological control proj- that nations where no releases were planned ect entails targeting the scale with a para - could be affected and that no international law sitoid, Tachariaephagus somervillei (Neumann or treaty adequately encompassed such cases et al. 2016). (Angulo and Gilna 2008). Postrelease, the con - Several recent technological advances in troversy rapidly expanded (Enserink 2010). molecular genetics have engendered tremen - The transgene of the Oxitec mosquito renders dous enthusiasm about the possibility that embryos that carry it inviable, so the heri - formerly intractable invasions might now tability concern was muted. The advent of become manageable or perhaps even eradi - Zika virus, transmitted by the same mosquito, cated. This prospect has been particularly quickly overtook proposals for treaties and aggressively explored for insects and fishes profound discussions of ethics. A leading ven - (Thresher et al. 2014), but it has also spawned ture capitalist purchased Oxitec (Pollack 2016), controversies. The ethics of killing sentient and the Oxitec mosquito is now being mass- organisms and concern about unintended produced and widely released in Piracicaba, consequences of eliminating a population are Brazil, with plans to release billions of individ - not unique to genetic technologies (Simberloff uals in that nation alone (Servick 2016). Voters 2012b). However, the idea of heritable change, in Monroe County (the Florida Keys), where with its prospect of changing the nature of a plans to release the Oxitec mosquito to com - species, is new. A genetic technology that bat dengue and yellow fever had long been would not be heritable is gene-silencing, or contested, approved the release in the wake of RNA interference (RNAi), which entails using the rapidly developing threat of Zika in double-stranded RNA to destroy messenger Florida (Langston 2016), but the U.S. Food RNA, thus blocking transcription. The main and Drug Administration, faced with a law - development obstacle is getting the double- suit from citizens and one town arguing that stranded RNA into the cell, but the fervor testing for potential impacts had been insuffi - for applying this technique to agricultural cient, canceled plans for the release ( Danley- insect pests and rodents as biomedical models Greiner 2017). suggests that progress is highly likely (Camp - The advent of RNA-guided gene drives, bell et al. 2015). Pilot projects on 2 beetle particularly those using the 2015 Science pests of agriculture in enclosed settings have “Breakthrough of the Year” (Travis 2015), succeeded (Baum et al. 2007, San Miguel and CRISPR-Cas9, has particularly excited both Scott 2016), and the internet has information geneticists and invasion managers, with sev - about gene-silencing projects targeting envi - eral lines of attack sketched out for how gene ronmentally problematic animals and plants, drives could greatly improve prospects for though not specifically on islands. In 2017, both maintenance management and eradica - the U.S. Environmental Protection Agency tion of invasive populations (Esvelt et al. 2014). registered 4 new products—plants genetically The technology is more accessible than that modified to produce RNAi that attacks corn employed to produce the Oxitec mosquito, rootworm (EPA 2017)—including corn seed and CRISPR-Cas9 in particular is even more expected to be marketed by 2019 (Zhang accessible than earlier gene drives. 952 WESTERN NORTH AMERICAN NATURALIST (2018), V OL . 78 N O. 4, P AGES 942 –958

Gene drives can work only on sexually improve, with more species and larger and reproducing organisms, and the speed with more complex islands becoming feasible tar - which a driven gene spreads depends on the gets. Challenges of course remain—for example, generation length of the organism; thus, a eradication of rodents on tropical islands (Rus - long-lived species that reaches sexual maturity sell and Holmes 2015), eradication of plants late would be a less promising target, unless (Simberloff 2013c), and costs and nontarget the conservation goal were formulated in a effects of sustained maintenance management very long-term framework. Because of their when eradication is not (yet) an option. How - life histories, invertebrates, small mammals ever, the entire enterprise of controlling such as rodents, fishes, and many plants would island invasions is marked by both incremen - seem to be possible targets. However, any tal improvement of existing technologies and autocidal gene will immediately stimulate nat - occasional “quantum innovations” that greatly ural selection to counter its impact. In fact, improve chances of controlling particular Hamilton (1967), in an early suggestion of species or entire classes of them. how such driven alleles might be used to Gene drives may be just such a quantum control pests, pointed out that an allele dis - innovation. However, the possibility of using torting sex ratios or destroying one sex (the gene drives for invasion management has led basis of several RNA-guided gene drive pro - to far more concerted concern, and even out - posals) would generate such strong selection right opposition, than the occasional opposi - on genes elsewhere in the genome (particularly tion to previous management projects (e.g., on different chromosomes) that these would Simberloff 2012b), largely because the modi - either quickly counteract the impact of the fied genes will not only be heritable but can guided gene or the population would go extinct. be designed to be autocidal—that is, to spread Such extinctions might have happened in the to the detriment of the population even to the past with naturally arising driven genes. point of extinction. For some projects where There is thus a race between the spreading, nonnative species eradication has been identi - driven, detrimental gene and natural selection fied as a priority conservation strategy, some in the rest of the genome to counteract it. If observers have already begun recommending eradication is the goal, the circumstances under genetic solutions if a safe, proven tool can be which a gene drive might succeed would be a developed (Esvelt et al. 2014, Campbell et al. relatively small population that would thus 2015). One such recommendation involves have fewer existing or new mutant antagonistic house mice on the Farallon Islands in San genes to combat the driven one. And the sce - Francisco Bay (Hawkes 2016), where previous nario would also be advantageous if this proposals to use toxic baits had aroused enor - smaller, more restricted population were iso - mous opposition based on concerns about lated, so immigrants carrying such genes animal welfare, animal rights, and nontarget would be less likely. In short, an island popu - impacts of chemicals. A group of prominent lation would seem to be a propitious target. conservation and environmental activists Esvelt et al. (2014) suggest that if a driven released the statement “A Call for Conserva - gene fails to eradicate a target, one could tion with a Conscience: No Place for Gene simply release another one, and then another, Drives in Conservation” (http://www.etcgroup in effect turning the technique into a mainte - .org/files/files/final_gene_drive_letter.pdf, nance management approach. However, in accessed 2 October 2016) at the World Con - the earliest stages of evaluating the efficacy servation Congress in September 2016, calling of the entire gene drive approach, the idea of for a permanent ban on any attempt to use Esvelt et al. (2014) seems at best tentative the technique in a conservation context. and unproven. In this instance, the horse has probably already left the barn. Science magazine rou - DISCUSSION tinely includes an advertisement from OriGene for “CRISPER/CAS 9 Genome Editing Kits” Successful control of invasive nonnative that will “Knock Out Any Gene,” while Cyagen species on islands has a long history and, Biosciences spammed many scientists on despite the ongoing arrival of new invaders, 9 January 2017 with an advertisement for “big the likelihood of success has continued to savings” on rat and mouse models for CRISPR SIMBERLOFF ET AL . ♦ PROGRESS IN CONTROLLING ISLAND INVASIONS 953

Knockout, Knockin, and Point Mutation mod - often led to a “treadmill effect” in which els. Jennifer Doudna, cofounder of the tech - another nonnative plant becomes dominant nology, has recently published CRISPR-Cas: (Thomas and Reid 2007). Removing one non - A Laboratory Manual, which includes step- native predator may release a previously sup - by-step protocols for applying CRISPR-Cas pressed predator, as on several islands where techniques to several animal systems (Doudna rat eradication precipitated a population and Mali 2016). Jon Cohen, a Science reporter, explosion of house mice (Caut et al. 2007). asking whether “any idiot can do it,” attempted Incremental improvements in eradication and an application under guidance, and he appar - management technologies and the prospect of ently meant to calm concern by concluding transformative new approaches, such as gene that “any idiot cannot do CRISPR” (Cohen drives, particularly suited for use on islands 2016). However, he immediately undercut his should inspire optimism that island biotas message by adding that “it takes, at least, basic can be saved and island ecosystems restored. laboratory skills.” The current situation is However, increased understanding of the reminiscent of the early days of application of complex nature of interactions among species basic PCR and Taq polymerase methods to suggests that, as Zavaleta et al. (2001) argued, amplify DNA segments in the 1980s, an eradication and management of island invasives approach that quickly became utterly routine should be undertaken in a whole-ecosystem for anyone with “basic laboratory skills.” context. To an extent this is already happen - The prospect of heritable genetic manipu - ing, as manifested by the increase in mammal lation and consequent population extinction eradications targeting multiple species and has led to many proposals for caution and invasive weed removal accompanied by seed - broad consideration of the venture’s ethical ing with native species. However, the prospect underpinnings as well as the possible unin - of larger and more complex projects becoming tended consequences, not least by researchers increasingly feasible makes the need to under - developing the technology (e.g., Oye et al. stand community interactions and ecosystem 2014, Baltimore et al. 2015). The United functioning, and to account for them, even States National Academy of Sciences (2016) more urgent. urged caution and continued research but not releases to the environment at this time. ACKNOWLEDGMENTS A general concern, aside from unintended We thank 2 anonymous reviewers of an direct and indirect consequences of elimi - earlier draft of the manuscript for substantial nating a species, is the possibility of a gene constructive comments and criticisms. drive somehow being inserted into the genome of a nontarget organism, although LITERATURE CITED there is no scientific evidence to date to sug - gest this is likely to happen. Another issue is ANGULO , E., AND B. G ILNA . 2008. International law should the possibility of drastic and even irrevoca - govern release of GM mosquitoes. Nature 454:158. ble actions by “rogue” players as gene drive ANONYMOUS . 2015. Red-whiskered Bulbul eradicated from Seychelles. SIF [Seychelles Island Foundation] technol ogy becomes increasingly accessible. Newsletter, January (Issue 27). Thus, despite the potential for strong selec - ASHMOLE , N.P., M.J. A SHMOLE , AND K.E.L. S IMMONS . tion against gene drive –mediated infertility, 1994. Seabird conservation and feral cats on Ascen - caution is warranted. sion Island, south Atlantic. Pages 94–121 in D.N. Nettleship, J. Burger, and M. Gochfield, editors, It has often been noted that simply remov - Seabirds on islands: threats, case studies and action ing or managing an invasive species does not plans. BirdLife International, Cambridge, United constitute ecological restoration of an island Kingdom. and may even create foreseen or unforeseen BALTIMORE , B.D., P. B ERG , M. B OTCHAN , D. C ARROLL , impediments (e.g., Zavaleta et al. 2001). R.A. C HARO , G. C HURCH , J.E. C ORN , G.Q. D ALEY , J.A. D OUDNA , M. F ENNER , ET AL . 2015. A prudent Removing an herbivore may allow hitherto path forward for genomic engineering and germline suppressed nonnative plants to dominate, as gene modification. Science 348:36–38. happened initially with fennel ( Foeniculum BARUN , A., K.C. C AMPBELL , C.C. H ANSON , AND D. S IM - vulgare ) when livestock were removed from BERLOFF . 2011. A review of the small Indian mon - goose management and eradications on islands. Santa Cruz Island (Dash and Gliessman 1994). Pages 17–25 in C.R. Veitch, M.N. Clout, and D.R. Removal of nonnative invasive plants has Towns, editors, Island invasives: eradication and 954 WESTERN NORTH AMERICAN NATURALIST (2018), V OL . 78 N O. 4, P AGES 942 –958

management. Manaaki Whenua Press, Auckland, CAUSTON , C., M.S. H ODDLE , AND R.G. V AN DRIESCHE . New Zealand. 2016. Protecting Galápagos plants from cottony BAUM , J.A., T. B OGAERT , W. C LINTON , G.R. H ECK , P. F ELD - cushion scale. Pages 215–220 in R. Van Driesche, D. MANN , O. I LAGAN , S. J OHNSON , G. P LAETINCK , T. Simberloff, B. Blossey, C. Causton, M. Hoddle, C. MUNYIKWA , M. P LEAU , ET AL . 2007. Control of Marks, K. Heinz, D. Wagner, and K. Warner, editors, coleopteran insect pests through RNA interference. Integrating biological control into conservation prac - Nature Biotechnology 25:1322–1326. tice. Wiley-Blackwell, Chichester, United Kingdom. BAUMHOVER , A.H., A.J. G RAHAM , B.A. B ITTER , D.E. H OP - CAUT , S., J.G. C ASANOVAS , E. V IRGOS , J. L OZANO , G.W. KINS , W.D. N EW , F.H. D UDLEY , AND R.C. B UCHLAND . WITMER , AND F. C OURCHAMP . 2007. Rats dying for 1955. Screw-worm control through release of ster - mice: modelling the competitor release effect. Aus - ilized flies. Journal of Economic Entomology 48: tral Ecology 32:858–868. 462–466. CHAPUIS , J.-L., Y. F RENOT , AND M. L EBOUVIER . 2004. BEACHY , J.R., R. N EVILLE , AND C. A RNOTT . 2011. Success - Recovery of native plant communities after eradica - ful control of an incipient invasive amphibian: tion of rabbits from the subantarctic Kerguelen Eleutherodactylus coqui on O’ahu, Hawai’i. Pages Islands, and influence of climate change. Biological 140–147 in C.R. Veitch, M.N. Clout, and D.R. Conservation 117:167–179. Towns, editors, Island invasives: eradication and CIVEYREL , L., AND D. S IMBERLOFF . 1996. A tale of two management. Proceedings of the International Con - snails: is the cure worse than the disease? Biodiver - ference on Island Invasives. IUCN, Gland, Switzer - sity and Conservation 5:1231–1252. land; The Centre for Biodiversity and Biosecurity CLOUT , M.N., AND P.A. W ILLIAMS , EDITORS . 2009. Invasive (CBB), Auckland, New Zealand. species management. Oxford University Press, New BEAVIS , L., AND L. J UNT . 2014. Macquarie Island declared York, NY. pest free after 7-year eradication program. ABC AU COCK , M.J.W. 2003. Risks of non-target impact versus News; [accessed April 2014]. http://www.abc.net stakeholder benefits in classical biological control of .au/news/2014-04-07/macquarie-island-declared arthropods: selected case studies from developing -pest-free-after-eradication-program/5373336 countries. Pages 25–33 in R.G. Van Driesche, editor, BOSER , C.L. 2016. Argentine ant eradication on Santa Proceedings of the International Symposium on Bio - Cruz Island [online Prezi presentation]. Posted 12 logical Control of Arthropods, Honolulu, Hawaii, January 2016; accessed 11 January 2017. https:// 14–18 January 2002. United States Department of prezi.com/amls43y0se-s/argentine-ant-eradication Agriculture, Forest Service, Morgantown, WV. -on-santa-cruz-island COCK , M.J.W., S.T. M URPHY , M.T.K. K AIRO , E. T HOMPSON , BOSER , C.L., C. H ANNA , K.R. F AULKNER , C. C ORY , J.M. R.J. M URPHY , AND A.W. F RANCIS . 2016. Trends in the RANDALL , AND S.A. M ORRISON . 2014. Argentine ant classical biological control of insect pests by insects: management in conservation areas: results of a pilot an update of the BIOCAT database. BioControl study. Monographs of the Western North American 61:349–363. Naturalist 7:518–530. COHEN , J . 2016. A reporter does CRISPR. Science BUDDENHAGEN , C.E., AND A. T YE . 2015. Lessons from 354:541. successful plant eradications in Galapagos: commit - COONAN , T.J., C.A. S CHWEMM , AND D.K. G ARCELON . 2010. ment is crucial. Biological Invasions 17:2893–2912. Decline and recovery of the island fox: a case study BUHS , J.B . 2004. The fire ant wars. University of Chicago for population recovery. Cambridge University Press, Chicago, IL. Press, Cambridge, United Kingdom. [CDFW] CALIFORNIA DEPARTMENT OF FISH AND WILD - CORBIN , J.D., AND C.M. D’A NTONIO . 2012. Gone but not LIFE . 2015. California State Wildlife Action Plan, forgotten? Invasive plants’ legacies on community 2015 update: a conservation legacy for Californians. and ecosystem properties. Invasive Plant Science A.G. Gonzales and J.Hoshi, editors. Prepared with and Management 5:117–124. assistance from Ascent Environmental, Inc. CDFW, CORY , C., AND J.J. K NAPP . 2014. A program to eradicate Sacramento, CA. twenty-four nonnative invasive plant species from CAMPBELL , K.J., G.S. B AXTER , P.J. M URRAY , B.E. Santa Cruz Island. Monographs of the Western COBLENTZ , AND C.J. D ONLAN . 2007. Development of North American Naturalist 7:455–464. a prolonged estrus effect for use in Judas goats. COWIE , R.H. 2011. Snails and slugs. Pages 634–643 in D. Applied Animal Behaviour Science 102(1–2):12–23. Simberloff and M. Rejmánek, editors, Encyclopedia CAMPBELL , K., J. B EEK , C.T. E ASON , A.S. G LEN , J. G OD - of biological invasions. University of California WIN , F. G OULD , N.D. H OLMES , G.R. H OWALD , F.M. Press, Berkeley, CA. MADDEN , J.B. P ONDER , ET AL . 2015. The next genera - CRUZ , F., C.J. D ONLAN , K. C AMPBELL , AND V. C ARRION . tion of rodent eradications: innovative technologies 2005. Conservation action in the Galapagos: feral and tools to improve species specificity and increase pig ( Sus scrofa ) eradication from Santiago Island. their feasibility on islands. Biological Conservation Biological Conservation 121:473–478. 185:47–58 DAHLSTEN , D.L . 1986. Control of invaders. Pages 275–302 CAMPBELL , K., AND C. D ONLAN . 2005. Feral goat eradica - in H.A. Mooney and J.A. Drake, editors, Biological tions on islands. Conservation Biology 19:1362–1374. invasions of North America and Hawaii. Springer- CARRION , V., C.J. D ONLAN , K.J. C AMPBELL , C. L AVOIE , AND Verlag, New York, NY. F. C RUZ . 2011. Archipelago-wide island restoration DANLEY -G REINER , K. 2017. FDA backs down from releas - in the Galapagos Islands: reducing costs of invasive ing genetically modified mosquitoes after lawsuit mammal eradication programs and reinvasion risk. threatened [online]. Florida Record, The Record PLOS ONE 6(5):e18835. Inc., Rolling Meadows, IL; [posted 8 January 2017; CARSON , R . 1962. Silent spring. Houghton Mifflin, Boston, accessed 26 September 2017]. http://flarecord.com/ MA. stories/511066542-fda-backs-down-from-releasing SIMBERLOFF ET AL . ♦ PROGRESS IN CONTROLLING ISLAND INVASIONS 955

-genetically-modified-mosquitoes-after-lawsuit- Biological Control of Weeds. Montana State Univer - threatened sity, Bozeman, MT. DASH , B., AND S. G LIESSMAN . 1994. Non-native species FUKUHARA , R., T. Y AMAGUCHI , H. U KUTA , S. R OY , J. eradication and native species enhancement: fennel TANAKA , AND G. O GURA . 2010. Development and on Santa Cruz Island. Pages 505–512 in W. Halvor - introduction of detection dogs in surveying for scats son and G. Maender, editors, The Fourth Califor - of small Indian mongoose as invasive alien species. nia Islands Symposium: update on the status of Journal of Veterinary Behavior 5:101–111. resources. Santa Barbara Museum of Natural His - GARDENER , M.R., R. A TKINSON , AND J.L. R ENTERÍA . 2010. tory, Santa Barbara, CA. Eradications and people: lessons from the plant DICKMAN , C.R. 1996. Overview of the impacts of feral eradication program in Galapagos. Restoration Ecol - cats on Australian native fauna. Australian Nature ogy 18:20–29. Conservation Agency, Canberra, Australia. GARDENER , M.R., M. T RUEMAN , C. B UDDENHAGEN , R. DIISE P ARTNERS . 2014. The database of island invasive HELENO , H. J ÄGER , R. A TKINSON , AND A. T YE . 2013. species eradications. Developed by Island Conserva - A pragmatic approach to the management of plant tion, Coastal Conservation Action Laboratory UCSC, invasions in Galápagos. Pages 349–374 in L. Fox - IUCN SSC Invasive Species Specialist Group, Uni - croft, D.M. Richardson, P. Pyšek, and P. Genovesi, versity of Auckland and Landcare Research New editors, Alien plant invasions in protected areas: Zealand. http://diise.islandconservation.org patterns, problems, and challenges. Springer, Dor - DITOMASO , J.M . 2011. Herbicides. Pages 323–331 in D. drecht, Netherlands. Simberloff and M. Rejmánek, editors, Encyclopedia GENOVESI , P., AND L. C ARNEVALI . 2011. Invasive alien of biological invasions. University of California species on European islands: eradication and priori - Press, Berkeley, CA. ties for future work. Pages 56–62 in C.R. Veitch, DODD , A.P . 1940. The biological campaign against M.N. Clout, and D.R. Towns, editors, Turning the prickly-pear. Commonwealth Prickly Pear Board, tide: the eradication of invasive species. Manaaki Sherwood, Australia. Whenua Press, Auckland, New Zealand. DOUDNA , J., AND P. M ALI , EDITORS . 2016. CRISPR-Cas: a GLEN , A., R. A TKINSON , K. C AMPBELL , E. H AGEN , N. laboratory manual. Cold Spring Harbor Laboratory HOLMES , B. K EITT , J.P. P ARKES , A. S AUNDERS , J. Press, Cold Spring Harbor, NY. SAWYER , AND H. T ORRES . 2013. Eradicating multiple DRAKE , J.A., H.A. M OONEY , F. DI CASTRI , R.H. G ROVES , invasive species on inhabited islands: the next big F.J. K RUGER , M. R EJMÁNEK , AND M. W ILLIAMSON , step in island restoration? Biological Invasions 15: EDITORS . 1989. Biological invasions: a global per - 2589–2603. spective. Wiley, Chichester, United Kingdom. GOODWIN , K.M., R.E. E NGEL , AND D.K. W EAVER . 2010. ELTON , C.E. 1958. The ecology of invasions by animals Trained dogs outperform human surveyors in the and plants. Methuen, London. detection of rare spotted knapweed ( Centaurea ENSERINK , M . 2010. GM mosquito trial alarms opponents, stoebe ). Invasive Plant Science and Management strains ties in Gates-funded project. Science 330: 3:113–121. 1030–1031. GREEN , P.T., AND D.J. O’D OWD . 2009. Management of [EPA] ENVIRONMENTAL PROTECTION AGENCY . 2017. EPA invasive invertebrates: lessons from the management registers innovative tool to control corn rootworm of an invasive alien ant. Pages 153–172 in M.N. [online]. News releases from headquarters, EPA Clout and P.A. Williams, editors, Invasive species Press Room; [posted 15 June 2017; accessed 27 Sep - management. Oxford University Press, New York, tember 2017]. https://www.epa.gov/newsreleases/ NY. epa-registers-innovative-tool-control-corn-root GRIFFITHS , R., F. B UCHANAN , K. B ROOME , AND B. B UT - worm LAND . 2012. Rangitoto and Motutapu – a starting ESVELT , K.M., A.L. S MIDLER , F. C ATTERUCCIA , AND G.M. point for future vertebrate pest eradications on CHURCH . 2014. Concerning RNA-guided gene drives inhabited islands. Pages 22–27 in R. Timm and R.A. for the alteration of wild populations. eLife 10.7554/ Baldwin, editors, Proceedings of the 25th Vertebrate eLife.03401 Pest Conference, Monterey, CA. FÉLIX -L IZÁRRAGA , M., A. A GUIRRE -M UÑOZ , B. K EITT , AND GUEDES , R.N.C., G. S MAGGHE , J.D. S TARK , AND N. H. B ERLANGA -G ARCÍA . 2009. Restauración de aves DESNEUX . 2016. Pesticide-induced stress in arthro - marinas en islas del Pacífico de Baja California con pod pests for optimized integrated pest management sistemas de atracción social. Memorias del Encuen - programs. Annual Review of Entomology 61:43–62. tro Nacional para la Conservación y el Desarrollo HADJISTERKOTIS , E., AND P.M. H EISE -P AVLOV . 2006. The Sustentable de las Islas de México. 23–26 June 2009. failure of the introduction of wild boar Sus scrofa in Ensenada, B.C., México. the island of Cyprus: a case study. European Journal FLINT , E.N., AND C. R EHKEMPER . 2002. Control and of Wildlife Research 52:213–215. eradication of the introduced grass, Cenchrus echi - HAMILTON , W.D . 1967. Extraordinary sex ratios. Science natus, at Laysan Island, central Pacific Ocean. Pages 156:477–488. 110–115 in C.R. Veitch and M.N. Clout, editors, HAVELL , D . 2014. Persistence and detection of weed Turning the tide: the eradication of invasive species. locations in some northern New Zealand island IUCN SSC Invasive Species Specialist Group, weed programmes. Pages 383–386 in M. Baker, IUCN, Gland, Switzerland. editor, Proceedings of the Nineteenth Australasian FOWLER , S.V., S. G ANSHAN , J. M AUREMOOTOO , AND Y. Weeds Conference. Tasmanian Weed Society, Hobart, MUNG ROO . 2000. Biological control of weeds in Tasmania. Mauritius: past successes revisited and present HAWKES , A. 2016. Re-coding for conservation. Bay challenges. Pages 43–50 in N.R. Spencer, editor, Nature, July–September. http://baynature.org/article/ Proceedings of the X International Symposium on re-coding-conservation 956 WESTERN NORTH AMERICAN NATURALIST (2018), V OL . 78 N O. 4, P AGES 942 –958

HERMS , D.A., AND D.G. M CCULLOUGH . 2011. Pesticides invasives: eradication and management. Manaaki for insect eradication. Pages 528–535 in D. Sim - Whenua Press, Auckland, New Zealand. berloff and M. Rejmánek, editors, Encyclopedia of KEITT , B., AND B. T ERSHY . 2003. Cat eradication signifi - biological invasions. University of California Press, cantly decreases shearwater mortality. Animal Con - Berkeley, CA. servation 6:307–308. HODDLE , M.S . 2016. Forecasting unintended effects of KERR , J.T . 2017. A cocktail of poisons. Science 356: natural enemies used for classical biological control of 1331–1332. invasive species. Pages 130–160 in R. Van Driesche, KLASSEN , W., AND C.F. C URTIS . 2005. History of the sterile D. Simberloff, B. Blossey, C. Causton, M. Hoddle, insect technique. Pages 3–36 in V.A. Dyck, J. Hen - C. Marks, K. Heinz, D. Wagner, and K. Warner, drichs, and A.S. Robinson, editors, Sterile insect editors, Integrating biological control into conserva - technique: principles and practice in area-wide tion practice. Wiley-Blackwell, Chichester, United integrated pest management. Springer, Dordrecht, Kingdom. Netherlands. HOELMER , K.A., AND J.K. G RACE . 1989. Citrus blackfly. KNAPP , J.J., P.T. S CHUYLER , K.N. W ALKER , N.L. M ACDON - Pages 147–165 in D.L. Dahlsten and R. Garcia, edi - ALD , AND S.A. M ORRISON . 2012. Benefits of support - tors, Eradication of exotic pests. Yale University ing invasive plant and animal eradication projects Press, New Haven, CT. with helicopters. Pages 188–191 in C.R. Veitch, M.N. HOFFMANN , B., G.M. L UQUE , C. B ELLARD , N.D. H OLMES , Clout, and D.R. Towns, editors, Island invasives: AND C.J. D ONLAN . 2016. Improving invasive ant eradication and management. Manaaki Whenua eradication as a conservation tool: a review. Biologi - Press, Auckland, New Zealand. cal Conservation 198:37–49. KRAUS , F . 2009. Alien reptiles and amphibians: a scientific HOLDICH , D.M., AND M. P ÖCKL . 2007. Invasive crus - compendium and analysis. Springer, Dordrecht, taceans in European inland waters. Pages 29–75 in F. Netherlands. Gherardi, editor, Biological invasions in inland LANGSTON , E . 2016. Voters in this Florida county just waters: profiles, distribution, and threats. Springer, approved GM mosquitoes to fight Zika. [Accessed Dordrecht, Netherlands. 13 November 2016]. http://www.motherjones.com/ HOOKER , J.D . 1867. Insular floras. Gardeners’ Chronicle, environment/2016/11/key-haven-monroe-county January. http://www.wku.edu/ ~smithch/biogeog/ -florida-gm-mosquitos-2016-election HOOK1866.htm LAPEYSSONIE , L . 1988. La médecine coloniale. Seghers, HUGHES , R.F., A.L. U OWOLO , AND T.P. T OGIA . 2012. Paris, France. Recovery of native forest after removal of an invasive LEARY , J.K., J. G OODING , A. R ADFORD , B. M AHNKEN , J. tree, Falcataria moluccana, in American Samoa. Bio - CHAPMAN , G. K AISER , C. C ORY , AND J. K NAPP . 2012. logical Invasions 14:1393–1413. Operational performance of a herbicide ballistic INNES , J., AND A. S AUNDERS . 2011. Eradicating multiple technology (HBT) helicopter platform targeting pests: an overview. Pages 177–181 in C.R. Veitch, incipient populations of miconia ( Miconia calve - M.N. Clout, and D.R. Towns, editors, Island inva - scens ) in Hawaiian watersheds [abstract]. California sives: eradication and management. Proceedings of Invasive Plant Council 2012 Symposium, Rohnert the International Conference on Island Invasives. Park, CA. IUCN, Gland, Switzerland; The Centre for Biodiver - LEVER , C. 2001. The cane toad. Westbury, Otley, United sity and Biosecurity (CBB), Auckland, New Zealand. Kingdom. JONES , H.P., N.D. H OLMES , S.H.M. B UTCHART , B.R. T ER - LOOPE , L.L., R.F. H UGHES , AND J.-Y. M EYER . 2013. Plant SHY , P.J. K APPES , I. C ORKERY , A. A GUIRRE -M UÑOZ , invasions of protected areas of tropical Pacific D.P. A RMSTRONG , E. B ONNAUD , A.A. B URBIDGE , AND islands, with special reference to Hawaii. Pages K. C AMPBELL . 2016. Invasive mammal eradication 313–348 in L. Foxcroft, D.M. Richardson, P. Pyšek, on islands results in substantial conservation gains. and P. Genovesi, editors, Alien plant invasions in Proceedings of the National Academy of Sciences protected areas: patterns, problems, and challenges. (USA) 113:4033–4038. Springer, Dordrecht, Netherlands. KAUFMAN , L., AND R.H. M ESSING . 2016. Preserving LORVELEC , O., AND M. P ASCAL . 2005. French attempts to Hawaiian dry forests by protecting wiliwili trees eradicate non-indigenous mammals and their conse - from Erythrina gall wasps. Pages 220–223 in R. Van quences for native biota. Biological Invasions 7: Driesche, D. Simberloff, B. Blossey, C. Causton, M. 135–140. Hoddle, C. Marks, K. Heinz, D. Wagner, and K. MACDONALD , D.W., AND L.A. H ARRINGTON . 2003. The Warner, editors, Integrating biological control into American mink: the triumph and tragedy of adapta - conservation practice. Wiley-Blackwell, Chichester, tion out of context. New Zealand Journal of Zoology United Kingdom. 30:421–441. KEAN , J.M., D.M. S UCKLING , N.J. S ULLIVAN , P.C. T OBIN , MALOY , O.C . 1997. White pine blister rust control in L.D. S TRINGER , G.R. S MITH , B. K IMBER , D.C. L EE , North America: a case history. Annual Review of R. F LORES VARGAS , J. F LETCHER , ET AL . 2017. Gerda: Phytopathology 35:87–109. global eradication and response database. [Accessed MOONEY , H.A., AND J.A. D RAKE , EDITORS . 1986. Biological 12 January 2017]. http://b3.net.nz/gerda invasions of North America and Hawaii. Springer- KEITT , B., K. C AMPBELL , A. S AUNDERS , M.N. C LOUT , Y. Verlag, New York, NY. WANG , R. H EINZ , K. N EWTON , AND B. T ERSHY . 2011. MORRISON , S.A., A.J. D ENICOLA , K. W ALKER , D. D EWEY , The Global Islands Invasive Vertebrate Eradication L. L AUGHRIN , R. W OLSTENHOLME , AND N. M ACDON - Database: a tool to improve and facilitate restora - ALD . 2016. An irruption interrupted: eradication of tion of island ecosystems. Pages 74–77 in C.R. Wild Turkeys Meleagris gallopavo from Santa Cruz Veitch, M.N. Clout, and D.R. Towns, editors, Island Island, California. Oryx 50:121–127. SIMBERLOFF ET AL . ♦ PROGRESS IN CONTROLLING ISLAND INVASIONS 957

NEUMANN , G., D.J. O’D OWD , P.J. G ULLAN , AND P.T. G REEN . 260–265 in D. Veitch and M. Clout, editors, Turning 2016. Diversity, endemism and origins of scale the tide: eradication of invasive species. Invasive insects on a tropical oceanic island: implications for Species Specialist Group of the World Conservation management of an invasive ant. Journal of Asia- Union (IUCN), Auckland, New Zealand. Pacific Entomology 19:159–166. ROY , S . 2011. Strategies to improve landscape scale man - NEWTON , K.M., M. M CKOWN , C. W OLF , H. G ELLERMAN , agement of mink populations in the west coast of T. C OONAN , D. R ICHARDS , A.L. H ARVEY , N.D. Scotland: lessons learned from the Uists 2001–2006. HOLMES , G. H OWALD , K. F AULKNER , ET AL . 2016. Pages 114–117 in C.R. Veitch, M.N. Clout, and D.R. Response of native species ten years after rat eradi - Towns, editors, Island invasives: eradication and cation on Anacapa Island, California. Journal of management. Manaaki Whenua Press, Auckland, Fish and Wildlife Management 7:72–85. New Zealand. NICO , L.G., AND S.J. W ALSH . 2011. Non-indigenous fresh - RUSSELL , J.C., AND N.D. H OLMES . 2015. Tropical island water fishes on tropical Pacific islands: a review of conservation: rat eradication for species recovery. eradication efforts. Pages 97–107 in C.R. Veitch, Biological Conservation 185:1–7. M.N. Clout, and D.R. Towns, editors, Island inva - SAN MIGUEL , K., AND J.G. S COTT . 2016. The next genera - sives: eradication and management. Proceedings of tion of insecticides: dsRNA is stable as a foliar- the International Conference on Island Invasives. applied insecticide. Pest Management Science 72: IUCN, Gland, Switzerland; The Centre for Biodiver - 801–809. sity and Biosecurity (CBB), Auckland, New Zealand. SARAT , E., E. M AZAUBERT , A. D UTARTE , N. P OULET , AND Y. NORDSTRÖM , M., J. H ÖGMANDER , AND J. N UMMELIN . 2002. SOUBEYRAN , EDITORS . 2015. Les espèces exotiques Variable responses of waterfowl breeding popula - envahissantes dans les milieux aquatiques. Volume tions to long-term removal of introduced American 2, Expériences de gestion. Office National de l’Eau mink. Ecography 25:385–394. et des Milieux Aquatiques, Vincennes, France. NORTH , S.G., D.J. B ULLOCK , AND M.E. D ULLOO . 1994. SAVIDGE , J.A., J.W. S TANFORD , R.N. R EED , G.R. H ADDOCK , Changes in the vegetation and reptile populations AND A.A. Y ACKEL ADAMS . 2011. Canine detection of on Round Island, Mauritius, following eradication of free-ranging brown treesnakes on Guam. New rabbits. Biological Conservation 67:21–28. Zealand Journal of Ecology 35:174–181. OPPEL , S., B.M. B EAVEN , M. B OLTON , J. V ICKERY , AND T.W. SCOTTISH NATURAL HERITAGE . 2013. Hebridian Mink Proj - BODEY . 2011. Eradication of invasive mammals on ect, Introduction – Phase 1 and Phase 2. Scottish islands inhabited by humans and domestic animals. Natural Heritage, Inverness, Scotland. Conservation Biology 25:232–240. SERVICK , K . 2016. Winged warriors. Science 354:164–167. OYE , K.A., K. E SVELT , E. A PPLETON , F. C ATTERUCCIA , G. SIMBERLOFF , D . 2005. Non-native species do threaten CHURCH , T. K UIKEN , S.B. L IGHTFOOT , J. M CNAMARA , the natural environment! Journal of Agricultural A. S MIDLER , AND J.P. C OLLINS . 2014. Regulating gene and Environmental Ethics 18:595–607. drives. Science 345:626–628. SIMBERLOFF , D . 2011a. SCOPE project. Pages 617–619 in PARKES , J . 2008. A feasibility study for the eradication of D. Simberloff and M. Rejmánek, editors, Encyclope - house mice from Gough Island. Royal Society for dia of biological invasions. University of California the Preservation of Birds Report No. 34. Sandy, Press, Berkeley, CA. Bedfordshire, United Kingdom. SIMBERLOFF , D . 2011b. Charles Elton—neither founder PEMBERTON , R.W., AND H. L IU . 2007. Control and persis - nor siren, but prophet. Pages 11–24 in D.M. tence of native Opuntia on Nevis and St. Kitts 50 Richardson, editor, Fifty years of invasion ecology. years after the introduction of Cactoblastis cactorum. Wiley, New York, NY. Biological Control 41:272–282. SIMBERLOFF , D . 2012a. Risks of biological control for PETERSEN , A.E. 1979. The breeding birds of Flatey and conservation purposes. BioControl 57:263–276. some adjoining islets in Breidafjördur in NW Ice - SIMBERLOFF , D. 2012 b. Nature, natives, nativism, and land. Náttúrufr 49:229–256. [In Icelandic with management: worldviews underlying controversies English summary.] in invasion biology. Environmental Ethics 34:5–25. POLLACK , A . 2016. A biotech evangelist seeks a Zika divi - SIMBERLOFF , D . 2013a. Biological invasions: much progress dend. New York Times, 6 March 2016, page BU1. plus several controversies. Contributions to Science REDDY , G.V., AND A. G UERRERO . 2010. New pheromones 9:7–16. and insect control strategies. Vitamins and Hor - SIMBERLOFF , D . 2013b. Invasive species. What everyone mones 83:493–519. needs to know. Oxford University Press, New York, REJMÁNEK , M., AND M.J. P ITCAIRN . 2002. When is eradi - NY. cation of exotic pest plants a realistic goal? Pages SIMBERLOFF , D . 2013c. Eradication—pipe dream or real 249–253 in C.R. Veitch and M.N. Clout, editors, option? Pages 549–559 in L. Foxcroft, D.M. Richard - Turning the tide: the eradication of invasive species. son, P. Pyšek, and P. Genovesi, editors, Alien plant IUCN SSC Invasive Species Specialist Group, invasions in protected areas: patterns, problems, and IUCN, Gland, Switzerland. challenges. Springer, Dordrecht, Netherlands. RITCHIE , J . 1920. The influence of man on animal life in SORENSEN , P.W., AND R.A. B ERGSTEDT . 2011. Sea lamprey. Scotland: a study in faunal evolution. Cambridge Pages 619–623 in D. Simberloff and M. Rejmánek, University Press, Cambridge, United Kingdom. editors, Encyclopedia of biological invasions. Uni - ROCAMORA , G., AND E. H ENRIETTE . 2017. Invasive alien versity of California Press, Berkeley, CA. species in Seychelles. University of Chicago Press, SOUTH GEORGIA HERITAGE TRUST . 2016. The South Geor - Chicago, IL. gia habitat restoration project: final report. South RODDA , G.H., T.H. F RITTS , E.W. C AMPBELL III, K. D EAN - Georgia Heritage Trust, Dundee, Scotland. BRADLEY , G. P ERRY , AND C.P. Q UALLS . 2002. Practical SPEAR , R.J . 2005. The great gypsy moth war. University of concerns in the eradication of island snakes. Pages Massachusetts Press, Amherst, MA. 958 WESTERN NORTH AMERICAN NATURALIST (2018), V OL . 78 N O. 4, P AGES 942 –958

SUCKLING , D.M . 2013. Benefits from biological control of sechellarum: ecology and conservation of an endan - weeds in New Zealand range from minimal to mas - gered species. Biological Conservation 61:93–106. sive: a retrospective analysis. Biological Control 66: WENNER , A.M., R.W. T HORP , AND J.F. B ARTHELL . 2009. 27–32. Biological control and eradication of feral honey THOMAS , M.B., AND A.M. R EID . 2007. Are exotic natural bee colonies on Santa Cruz Island, California: a enemies an effective way of controlling invasive summary. Pages 327–335 in C.C. Damiani and D.K. plants? Trends in Ecology and Evolution 22: Garcelon, editors, Proceedings of the 7th California 447–453. Islands Symposium. Institute for Wildlife Studies, THOMSON , G., AND S. E BBERT . 2005. Eradication of arctic Arcata, CA. foxes with incidental wildlife observations at Attu WEST , C.J., AND A.M. T HOMPSON . 2013. Small, dynamic, Island, Alaska in 1999. U.S. Fish and Wildlife Ser - and recently settled: responding to the impact of vice report AMNWR 05/03, Homer, AK. plant invasions in the New Zealand (Aotearoa) THOMSON , G.M . 1922. The naturalisation of animals and Archipelago. Pages 285–311 in L. Foxcroft, D.M. plants in New Zealand. Cambridge University Press, Richardson, P. Pyšek, and P. Genovesi, editors, Alien Cambridge, United Kingdom. plant invasions in protected areas: patterns, problems, THRESHER , R.E., K. K AYES , N.J. B AX , J. T EEM , T.J. B ENFEY , and challenges. Springer, Dordrecht, Netherlands. AND F. G OULD . 2014. Genetic control of invasive fish: WETTERER , J.K., AND S.D. P ORTER . 2003. The little fire technological options and its role in integrated pest ant, Wasmannia auropunctata: distribution, impact, management. Biological Invasions 16:1201–1216. and control. Sociobiology 42:1–41. TOBIN , P.C., J.M. K EAN , D.M. S UCKLING , D.G. M CCUL - WHISSON , D.A . 2011. Pesticides (mammal). Pages 535–539 LOUGH , D.A. H ERMS , AND L.D. S TRINGER . 2014. in D. Simberloff and M. Rejmánek, editors, Encyclo - Determinants of successful arthropod eradication pedia of biological invasions. University of California programs. Biological Invasions 16:401–414. Press, Berkeley, CA. TOWNS , D.R., AND K.G. B ROOME . 2003. From small Maria WILLIAMSON , M., AND A. F ITTER . 1996. The varying suc - to massive Campbell: forty years of rat eradications cess of invaders. Ecology 77:1661–1666. from New Zealand islands. New Zealand Journal of WOLF , S., B. K EITT , A. A GUIRRE -M UÑOZ , B. T ERSHY , E. Zoology 30:377–398. PALACIOS , AND D. C ROLL . 2006. Transboundary sea- TRAVIS , J . 2015. Making the cut. Science 350:1456–1457. bird conservation in an important North American UNITED STATES NATIONAL ACADEMY OF SCIENCES . 2016. marine ecoregion. Environmental Conservation 33: Gene drives on the horizon. National Academies 294–305. Press, Washington, DC. YADAV , R.P., AND A. S INGH . 2011. Pesticides (fish and URICH , J.W . 1931. The mongoose in Trinidad. Tropical mollusc). Pages 525–527 in D. Simberloff and M. Agriculture 8:95–97. Rejmánek, editors, Encyclopedia of biological inva - VAN DRIESCHE , R., M. H ODDLE , AND T. C ENTER . 2008. sions. University of California Press, Berkeley, CA. Control of pests and weeds by natural enemies. YALDWYN , J.C., AND W.R. W EBBER . 2011. Annotated check - Blackwell, Malden, MA. list of New Zealand Decapoda (Arthropoda: Crus - VAN DRIESCHE , R., D. S IMBERLOFF , B. B LOSSEY , C. C AUS - tacea). Tuhinga 22:171–272. TON , M. H ODDLE , C. M ARKS , K. H EINZ , D. W AG - ZAVALETA , E.S., R.J. H OBBS , AND H.A. M OONEY . 2001. NER , AND K. W ARNER , EDITORS . 2016. Integrating Viewing invasive species removal in a whole- biological control into conservation practice. Wiley- ecosystem context. Trends in Ecology and Evolution Blackwell, Chichester, United Kingdom. 16:454–459. VEITCH , D., AND M. C LOUT , EDITORS . 2002. Turning the ZHANG , S. 2017. The EPA quietly approved Monsanto’s tide: eradication of invasive species. Invasive Species new genetic-engineering technology [online]. The Specialist Group of the World Conservation Union Atlantic, Science Section; [posted 23 June 2017, (IUCN), Auckland, New Zealand. accessed 27 September 2017]. https://www.the VEITCH , C.R., M.N. C LOUT , AND D.R. T OWNS , EDITORS . atlantic.com/science/archive/2017/06/monsanto-rna 2011. Island invasives: eradication and management. -interference/531288 Proceedings of the International Conference on Island Invasives. Manaaki Whenua Press, Auckland, Received 26 February 2017 New Zealand. Revised 28 September 2017 VINCE , G . 2011. Embracing invasives. Science 331: Accepted 19 December 2017 1383–1384. Published online 22 October 2018 WALLACE , A.R . 1880. Island life. Macmillan, London. WATSON , J., C. W ARMAN , D. T ODD , AND V. L ABOUDALLON . 1992. The Seychelles Magpie Robin Copsychus