Burbidge, A.A. 2001 to 2010 and beyond: Trends and future directions in the eradication of invasive species on islands CLOSING ADDRESS 2001 to 2010 and beyond: Trends and future directions in the eradication of invasive species on islands A.A. Burbidge Department of Environment and Conservation, PO Box 51, Wanneroo, WA 6946, Australia; and Consultant Conservation Biologist. <[email protected]>. Abstract My interest in island conservation grew out of work to conserve Australia’s mammals; the shocking figure of 22 extinctions since 1788 would have been 30 without populations on continental islands. My efforts to eradicate invasive animals on islands commenced in 1969 with the eradication of rabbits (Oryctolagus cuniculus) on the 19 ha Carnac Island. Eradication of goats (Capra hircus) on the 4267 ha Bernier Island and ship (black) rats (Rattus rattus) on the 24 ha Bedout Island were followed by many others in Western Australia. The last one I led was the eradication of rats and feral cats (Felis catus) on an archipelago – the Montebello Islands. Recently, I have participated in developing a quarantine management system for the 23,000 ha Barrow Island. This personal journey mirrors, to some extent, the development of island management for biodiversity conservation worldwide. Island management for biodiversity conservation is very important. Islands contain a disproportionate share of the world’s terrestrial species, including many endemics; islands are vital breeding places for seabirds, sea turtles and seals; islands are especially vulnerable to the impact of invasive species; eradication of invasive species is possible on islands; and successful conservation actions, especially eradication of invasives, are among those with greatest benefit to biodiversity at the least cost. A comparison between papers delivered at the 2001 and 2010 conferences shows that more nations are conducting invasive species eradications; a wider array of invasive species is being addressed; larger and more remote islands are now the subject of invasive species work and more projects are being conducted on inhabited islands. Future issues that remain unresolved include rat eradication on tropical rain-forested islands; dealing with difficult species such as tramp ants and mongoose; reducing impacts on non- target species; dealing with inhabited islands, animal welfare and ethics; properly documenting costs and benefits; and the implications of project failure. Prevention is better than cure and island biosecurity is becoming increasingly important. The 2010 conference has demonstrated the importance of managing invasive species on islands across the spectrum of prevention (biosecurity/quarantine), detection, control and eradication, plus the necessary post-project monitoring. It is clear that managing biodiversity on islands is extremely cost effective and it is not surprising that interest in this subject is increasing worldwide. Simberloff’s challenge in the keynote address at the 2001 conference: ‘Today Tiritiri Matangi, tomorrow the world!’ is as relevant today as it was then. Keywords: Biosecurity, invasive species, rabbits, Oryctolagus cuniculus, goats, Capra hircus, ship rats, Rattus rattus, feral cats, Felis catus INTRODUCTION I was privileged to work for a series of Western mirrors the development of invasive species management Australian conservation agencies for more than 30 years on islands worldwide. My first involvement with the as a research scientist and manager, but never during that eradication of an invasive species on an island was in time did my job description include the word ‘island’. So, 1969. European rabbits were destroying vegetation on how did I become involved in island conservation and the Carnac Island (19 ha), a nature reserve in the Indian Ocean eradication of invasive species on islands? near Perth. Carnac Island is important for seabird nesting, and the nesting burrows of one species, little penguin My interest in island conservation started with work to (Eudyptula minor), were collapsing. After consulting conserve Australia’s mammals. Since European settlement with vertebrate pest researchers in the State’s Agriculture of Australia began in 1788, 22 species (7%) of terrestrial Protection Board, we introduced the myxoma virus to the mammals have become extinct. Without islands, however, island’s rabbits, in the hope that they had not previously this already-shocking figure would be 30, as eight been exposed to it and had no immunity. Immunity was species that became extinct on the mainland persisted present, so the next attempt was to use a toxin; in this case on continental islands (Burbidge et al. 2008). Australian 1080 in carrots. After a couple of days of feeding with islands also have secure populations of many indigenous toxin-free carrots in late summer (when food was limiting), mammal species that are threatened with extinction on the a single feed of carrots with 1080 was effective. mainland (Burbidge 1999). These extinctions and declines are, to a great extent, due to invasive species, primarily My next job was very much concerned with mammal predators, such as the European red fox (Vulpes vulpes) conservation. Bernier and Dorre Islands in Shark Bay have and feral cats (Felis catus), but also herbivores, such as populations of five endangered mammal species, most of rabbits (Oryctolagus cuniculus), sheep (Ovis aries), goats which are extinct on the mainland. Around 1900, before the (Capra hircus), pigs (Sus scrofa) and cattle (Bos taurus) islands were included in the protected area system, goats (Burbidge and Manly 1999; McKenzie et al. 2007). The (Capra hircus) were introduced to both islands; however, rate of extinctions in Australia suggests that, from an they persisted only on one – Bernier (4267 ha). There they ecological point of view, it is the world’s largest island, not were competing with native mammals for food, destroying a continent. The role of introduced rats and mice in causing the mammals’ diurnal shelter and causing erosion. In 1969, extinctions on ‘continental’ Australia is uncertain. we commenced shooting the goats and in subsequent years intensified this option. However, despite using fixed-wing I would like to start by briefly outlining my personal aircraft to muster goats towards shooters, and despite journey in island management, as this, to some extent, assistance from a platoon of Ghurkhas of the British Army, Pages 515-519 In: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.). 2011. Island invasives: eradication and management. IUCN, Gland, Switzerland. 515 Island invasives: eradication and management ground-based shooting, while adequate for control, clearly Two highly threatened native mammals, mala was not going to achieve eradication. By the early 1980s, Lagorchestes hirsutus and djoongari Pseudomys fieldi, helicopter shooting of feral donkeys (Equus asinus) and were introduced to Trimouille and North West Islands feral cattle was underway in northern Australia and we respectively in 1998 and 1999 (Langford and Burbidge were able to employ an experienced pilot-shooter team 2001), and in 2010 spectacled hare-wallabies (Lagorchestes on Bernier Island. They succeeded in eradicating the conspicillatus) and golden bandicoots (Isoodon auratus) remaining goats in three days. were reintroduced to Hermite Island from nearby Barrow Island. Two birds, spinifexbird Eremiornis carteri and Then I moved to rats. Ship rats (Rattus rattus) had been Barrow Island black-and-white fairy-wren Malurus introduced to many islands in the north west of Western leucopterus leucopterus, are also being translocated to Australia, presumably from the many small pearling Hermite. vessels that were active in the latter part of the 19th Century. Bedout Island (24 ha) was one such island and is Barrow Island (23,000 ha), off the north west of important for seabird breeding. While the breeding success Western Australia, is one of the most important island of larger seabirds such as brown and masked boobies (Sula conservation reserves anywhere in the world, with several leucogaster and S. dactylatra) and lesser frigate-birds threatened mammal species, many endemic taxa, sea turtle (Fregata ariel) was unaffected, smaller species such as rookeries and unique ecosystems. It has had a producing common noddy (Anous stolidus), and roseate and sooty oilfield on it since the 1960s and a quarantine system terns (Sterna dougallii and S. fuscata) had abandoned to protect its values developed during the early years of the island. In 1981, after again taking advice from local development. After the eradication of ship rats from a vertebrate pest experts and examining the literature on small portion of the island (Morris 2001) it is now one of island eradications, we used oats, vacuum-impregnated the largest land masses in the world with no introduced with Pindone as the bait and laid it on a grid over the mammals. Recently, the Western Australian and Australian island. Follow-up surveys confirmed eradication and since governments approved the construction of a large liquefied then there have been reports of recolonisation by common natural gas plant on the island. The greatest risk of such noddy and sooty tern. a large development (estimated cost AU$43billion, up to 3500 construction workers on the island) is the introduction Many other island eradications followed, including of invasive species, and one condition of approval was the rats, mice, foxes, rabbits and cats. These are summarised development and approval