New Zealand as a leader in conservation practice and invasion management

ABSTRACT

New Zealand has played a prominent role in conservation and especially in invasion management. The plethora of 19^th century animal and plant invasions led to much research, beginning in the early 20^th century, on their impacts and how to counteract them. New Zealand particularly became a leader in control and eradication of mammals and in biological control of pestiferous insects and plants. By hosting international conferences on eradicating invasions, and by mounting ambitious, inspirational projects with innovative technologies, New Zealand further increased its influence in this area. The nation has also inspired the world with vigorous, innovative attempts to rescue endemic animal species on the brink of extinction. An impressive New Zealand programme of reserves for conservation of marine species and ecosystems is threatened by the fact that conservation goals and those of commerce and recreation can never fully align. As in other nations with globally important biodiversity, New Zealand has seen disputes between its native inhabitants and European colonists and their descendants over conservation and customary use of this resource. Recognition of a rightful Māori role in these matters, both in the Treaty of Waitangi and recently, greatly surpasses deference given elsewhere to native peoples on related issues, but implementing this role remains challenging.

KEYWORDS:

• Biological control
• biological invasions
• customary use
• eradication
• introduced species
• Lazarus effect
• marine reserves

Introduction

As one who has occasionally visited New Zealand, long admired the conservation-mindedness of its citizenry, and watched with great interest the founding and evolution of the Department of Conservation (DOC), I am honoured to have been invited to write an editorial to accompany this special issue. My contribution is perhaps best seen as a view from an educated outsider with a background in international conservation, and surely my perceptions and coverage are strongly influenced by my greater interest in and knowledge of certain aspects of conservation than of others.

New Zealand is marketed and globally perceived, if not as a pristine paradise, at least as a nation with wonderful natural features and a national commitment to preserving them. Surely such an impression is buttressed by the myriad travellers who visit specifically to experience the natural beauty and who stick to relatively untrammelled areas. In a belated honeymoon many years ago, my wife and I flew into Queenstown and traversed the Routeburn Track. The massive Nothofagus forests, kaka (Nestor meridionalis) and other birds, and general dearth of people accorded well with the image of a nature-lover’s dream. On the same trip, however, near Queenstown we saw substantial forest damage by possums (Trichosurus vulpecula) and, later near Auckland, a pitifully small remnant patch of towering kauri (Agathis australis) trees surrounded by agriculture. As an ecologist I am well aware of what has been lost, and why, but also of the inspiring efforts, especially recently, to save what is left and to restore at least some of the landscape to a semblance of its earlier state.

In his splendid history of conservation in New Zealand, Young (2004) recounts in some detail the massive amounts of habitat destruction, the frequently wanton killing of birds, and the staggering number of introduced non-native species, but also the growing awareness of a conservation problem in the early 20^th century and incipient efforts to do something about it, right through the establishment and early history of DOC and the Parliamentary Commissioner for the Environment. I would be foolish to attempt to duplicate that effort. Rather, I will give my impression of the status of conservation in New Zealand today and the nation’s historic and current role in global conservation.

Impacts of biological invasions

To the conservation community and to conservation scientists in general, New Zealand is especially known for its many biological invasions, their impacts, and recent great strides in managing and even eradicating them. In addition to Young (2004), Druett (1983), King (1984), and McDowall (1994) describe the enormous effort by individuals, acclimatisation societies, and New Zealand government agencies in introducing, spreading, and protecting many non-native species, particularly of mammals and fishes, in the 19^th and early 20^th centuries. In light of this avalanche of introductions, it is perhaps not surprising that New Zealanders would be among the first to recognise some of the problems invaders pose and to initiate scientific study of them. Although the advent of modern invasion biology is often credited to Elton (1958) and more properly should be associated with the SCOPE programme of the 1980s (Simberloff 2011), several early works by New Zealanders remarkably adumbrated many of today’s major themes (see Simberloff 2011). Two deserve special note as being widely recognised today. Thomson (1922) produced a remarkable annotated list of all the introduced plants and animals in New Zealand for which he could find data; this work is so important that it continues to be exploited by modern invasion biologists seeking to understand patterns and mechanisms of invasions, particularly for bird introductions. Although a few 19^th century authors produced comprehensive lists of introduced species of particular taxa in particular places (e.g., Kirk 1895), none were nearly as comprehensive and systematic as Thomson’s book. Herbert Guthrie-Smith’s 1921 account of his many years on a New Zealand sheep farm includes remarkably detailed accounts of several invasions of both animals and plants. Although not widely cited by biologists, it has been through several editions and reprintings and is viewed by historians, especially environmental historians, as a classic. It certainly emphasized the issue of invasions to an audience that would not otherwise have been so interested in them.

Early concerns with impacts of introduced species in New Zealand, as elsewhere, were rarely about impacts on native biota. Rather, they focussed primarily on detrimental effects on agriculture, forestry, and hunting. For instance, California quail (Callipepla californica), introduced as a game bird in 1864, were deplored by the 1870s for damaging crops, and the house sparrow (Passer domesticus), introduced in the 1860s, was condemned by the 1870s for eating grain and fruit, with ‘sparrow clubs’ established to promote killing them (McDowall 1994). The 1870s also saw rapidly growing disenchantment with previously introduced European rabbits (Oryctolagus cuniculus) because they were devastating sheep pastures (Young 2004); unfortunately, the response was to introduce mustelids (McDowall 1994; Young 2004; King 2017). European hares (Lepus europaeus), introduced for hunting from the 1850s through the 1870s, were by the late 1870s recognised as pests of agriculture and silviculture (McDowall 1994).

However, the late 19^th century also saw increasing recognition of how invasions devastated native species, leading to the books listed above. A lay 1872 writer lamented in particular the threat to native birds (cited by McDowall 1994). Ornithologist Buller (1870) warned of the danger Norway rats (Rattus norvegicus) posed to native birds and crayfish, later sounding an alarm about the potential impact of ferrets (Mustela furo) on native birds (Buller 1877, 1894). Māori author Te Wehi (1874), lamenting forest destruction, indicted introduced cats, rats, and honeybees (Apis mellifera) for the decline of native bird populations. By 1892, Walsh recognised red deer (Cervus elaphus) introduced for hunting as a threat to native forests, additionally indicting mustelids introduced to control rabbits for devastating native birds. In 1894 Buller similarly cited mustelids as causing massive declines of native birds. A sad irony is that both scientists and lay critics had warned of exactly this consequence of mustelid introductions, but the government, influenced by farmers, nevertheless proceeded to import and liberate them (Wells 2006).

It is worth noting that many of the explorer-naturalists of the late 18^th and the 19^th centuries who established the biogeography of the earth noted the presence of non-native species in various places, but very few of them considered such invasions in an ecological light. Perhaps this is unsurprising, as the science of ecology did not exist until the late 19^th century. Darwin and Wallace stood out for their recognition of the ecological threat invasions pose, both citing New Zealand biota as among those threatened by non-native species. In 1890, Wallace (1890) described impacts of English watercress (probably Apium nodiflorum) and the Old World housefly (Musca domestica) on native New Zealand species and ecosystems, as well as damage by boar and pigs (Sus scrofa) to agriculture. In ‘The origin of species by means of natural selection,’ Darwin (1859) even used New Zealand as a prime example in pointing to impacts of non-native species to exemplify the ‘struggle for life’ driving natural selection. For instance, he argued that ‘if all the animals and plants of Great Britain were set free in New Zealand, a multitude of British forms would in the course of time become thoroughly naturalized there, and would exterminate many of the natives’ (p. 337), and he extended this argument to suggest that northern hemisphere species are generally stronger competitors than those of the southern hemisphere: ‘hardly a single inhabitant of the southern hemisphere has become wild in any part of Europe … the productions of Great Britain stand much higher in scale than those of New Zealand’ (p. 337).

In short, by the time biological invasions began to receive more ecological attention in the 20^th century, it is unsurprising that New Zealand should be seen as a main example, perhaps as an object lesson, in the scope of the problem. Most attention was focussed on animals, especially mammals, but Guthrie-Smith (1921) described the rapid spread of many non-native plants in New Zealand, and Cockayne (1911, 1928) exhaustively tabulated the non-native plants in various New Zealand habitats. Allan (1936), a protegé of Cockayne, explored the details of the impact of some invasive plants on native plants. Clark (1949), a geographer, depicted with a broad brush many of the introduced plants and animals spreading over the South Island, cited several of the examples Allan (1936) had detailed, such as gorse (Ulex europaeus), and introduced the New Zealand invasion phenomenon to a broad readership beyond biologists. Allan’s paper is of particular interest. Previously, descriptions or predictions about invasion impacts, even when advanced by scientists, were essentially conjectures based on scattered observations, assumptions, and analogies. Allan dissected the phenomenon for the entire introduced flora of New Zealand and explored in detail the reasons why some species persisted and spread, others spread and then declined, and still others remained restricted to well-tended gardens. In the process, he anticipated, as had Cockayne (1928), the thesis in modern invasion biology that many plant invaders are passengers rather than drivers of environmental change (MacDougall and Turkington 2005).

Elton (1958) cited New Zealand and Hawaii invasions extensively in his discussion of the impacts invasions wreak on islands, and his book was widely read, particularly as modern invasion biology arose in the 1980s (Simberloff 2011). Bates (1956), a nearly contemporaneous predecessor to Elton, similarly cited New Zealand and Hawaii as the paradigmatic extreme examples of the impact of invasions. I have previously called attention to the puzzling lack of New Zealand participation in the SCOPE project that initiated the explosive growth of invasion biology in the 1980s (Simberloff 2011, p. 21) and suggested this matter as a promising area of historical research, a suggestion that has not, to my knowledge, induced any study. Particularly given the enormous influence of New Zealand scientists from the outset of the modern field on its rapid growth (see, e.g. Veitch and Clout 2002; Townsend 2003; Allen and Lee 2006; Fukami et al. 2006; Towns et al. 2011; Veitch et al. 2011, 2019; Russell and Blackburn 2017; Lester 2018), the absence of participation in the SCOPE project is mysterious.

Terrestrial invasion management

Although New Zealand is widely known for the environmental destruction wrought by invasions, it is also famous for efforts to redress the damage and especially for technological advances in managing and eradicating invaders. A simple statistic makes this point. The Database of Island Invasive Species Eradications (DIISE) tracks attempted eradications of vertebrate invaders on islands (DIISE Partners 2014). My scan of DIISE in 2016 showed a total of 1,376 attempted eradications, of which 424 were conducted by New Zealand, more than twice as many as the nation next most active in this regard (Australia) and more than five times as many as the United States.

The University of Auckland hosted two large conferences (2001 and 2010), the proceedings of which (Veitch and Clout 2002; Veitch et al. 2011) are the major documents in the literature on eradication of invasive species (both animals and plants, but primarily the former), reporting successes, failures, and a host of new or improved technologies. Some statistics from these large conferences are instructive about both the growth of eradication and management as parts of invasion biology and the key role of New Zealand in that growth. In addition to many abstracts in both proceedings, there were 52 papers in the 2001 conference (of which 17 focussed on New Zealand projects) and 93 papers in the 2010 conference (of which 20 focussed on New Zealand projects). A close examination of the papers in the 2010 conference, attended by 240 delegates from at least 20 nations, gives a sense of both progress in eradication in New Zealand and globally and also of the influence of New Zealand on progress in the field. New techniques were featured in 22 papers, of which nine reported on New Zealand projects. Of the other 13 presentations on new techniques, six relied substantially on previous developments in New Zealand. Of 21 overviews and proposals, 14 related to New Zealand. Twenty-four papers reported results or outcomes; six of these were of New Zealand projects. Finally, 25 papers were on ‘People, Policy, and Prevention’, a major recent and ongoing thrust of invasion science that came with the increasing recognition that progress on the ground involves more than just biology and entails sociological, political, and economic aspects. Of these 25 papers, 11 reported on New Zealand projects, while another three involved foreign projects conducted wholly or partly by New Zealand researchers.

Reflected in the papers is another development signalling New Zealand’s global importance in progress on managing and eradicating invaders: commercial New Zealand enterprises specialising in technologies and products for use in both New Zealand and overseas. Such products include traps targeting particular invaders while excluding non-target organisms and fences to exclude entire suites of non-native species. These enterprises are in addition to environmental management companies who contract to conduct eradications throughout the world. New Zealand is so well known for this sort of service that Boyle (2011), in the best novel to date incorporating issues of biological invasions and management, has as a lead character Frazier Carter, a stereotypical Kiwi and founder of Island Healers, a New Zealand firm contracted by the United States National Park Service to eradicate introduced pigs on Santa Cruz Island in the California Channel Islands. Frazier and his Kiwi crew are famed for having eradicated invasive mammals from other islands and are depicted heroically and successfully tracking pigs with their dogs through dense brush on steep mountains.

The third international conference on eradicating species was held in 2017, this time not in New Zealand but in Dundee, Scotland (Veitch et al. 2019). This was an even larger conference than the two in Auckland, but despite its location 17,848 km from Auckland, New Zealand scientists continued to be extremely well represented, particularly but not solely in the section on rodent eradication. Of 107 published papers, 13 were on New Zealand projects and another 25 included New Zealand scientists as parts of teams working in other areas distributed worldwide, exemplifying the growing export of technology developed in New Zealand and the continuing global engagement of New Zealand invasion scientists and managers. Noteworthy is the collaboration of New Zealand scientists with those of Australia and the United States in GBIRd, the leading project to use gene drives to control or eradicate invasive species, a dramatic new technology that, if successful, promises major progress in solving hitherto intractable problems (Campbell et al. 2019). As in the two Auckland conferences (Simberloff et al. 2018), contributions on managing invasive plants were few, only two on eradication plus three on mapping and survey. However, the most impressive was the account by West and Havell (2019) on the 45-year project to eradicate invasive plants from Raoul Island. So far, 11 species have been eradicated and nine transformer species are currently targeted.

New Zealand has also been a leader in the management technique of biological control from the inception of the field in the mid-19^th century through the present. Biological control explicitly aims not to eradicate invasive species, but rather to achieve an ongoing homeostatic relationship between the biocontrol agents and the target pest characterised by low populations of both. In New Zealand as elsewhere, the great majority of targeted pests are non-native (‘classical biological control’), but native species have also been targeted in campaigns in which non-native predators, parasites, or diseases have been introduced in an attempt to control native species. In fact, in New Zealand the greatest number of deliberate introductions targeting a single pest (36) were made against the endemic scarab beetle Costelytra zealandica, or grass grub, a pest of pasture grasses, horticultural crops, and vines, many of which are themselves introduced (Cameron et al. 1989). Despite this effort, the main management tool against the grass grub today is prophylactic use of synthetic pyrethroids (González-Chang 2016). This case exemplifies two aspects of biological control in New Zealand and worldwide. First, most effort has been expended against pests of agriculture or silviculture rather than against species causing conservation concern, although an increasing number of projects now have the latter goal both internationally and in New Zealand (Van Driesche et al. 2016). Second, most biological control introductions either do not succeed in controlling the target pest or exert only partial control, and other techniques (e.g., pesticides or herbicides) are still used.

Of course New Zealand was the site of one of the world’s worst biological control misfires, in terms of non-target impacts, with the 19^th century introduction of mustelids to control rabbits (King 1984, 2017). New Zealand dodged a likely even worse bullet in the 19^th century when mongooses (Herpestes sp.) imported for rabbit control failed to establish populations (McDowall 1994; King 2019); mongooses introduced for rat and snake control have devastated native avifauna, mammals, reptiles, and amphibians on many islands worldwide (Hays 2011). Introduced mammalian predators such as mongooses and mustelids are now widely recognised as inappropriate biological control agents (Van Driesche and Simberloff 2016), partly because of the hecatomb occasioned by mustelids in New Zealand. Most biological projects in the 20^th and 21^st centuries have involved insects introduced to control introduced pest insects and plants. A quaint early example targeting a native species was the introduction by early English settlers in New Zealand of English houseflies in the hope that they would outcompete a native flesh-fly (sarcophagid), a feat Kirk (1895) believed they accomplished. He did not provide evidence or discuss other impacts of the housefly.

More in the mainstream of the early history of biological control was the shipment in 1874 of predators of aphids from England to New Zealand, resulting in the first establishment of a predator (the ladybeetle Coccinella undecimpunctata) transported overseas, though in this case without notable effect on the target (DeBach and Rosen 1991). More consequentially, the source of the Australian vedalia beetle (Rodolia cardinalis) introduced to California in 1889 to control the cottony cushion scale (Icerya purchasi; a pest particularly of citrus in California) was Napier, New Zealand, not Australia as widely cited in the biocontrol literature (Cameron et al. 1989; DeBach and Rosen 1991). This project is one of the most heralded lasting successes of early biological control. The collector, Albert Koebele, had stopped in Auckland en route back to California from Australia and learned that the scale had inadvertently arrived in New Zealand several years earlier, devastated vegetation in the Auckland area, but had been almost eliminated after the accidental introduction of the vedalia beetle. He found few scales and no beetles in Auckland but many of both species in Napier; these were the source of the California beetle introductions. Fortuitous inadvertent introduction such as this of insects that later turn out to attack previously introduced pests is not uncommon. Another New Zealand example is the parasitic wasp Aphytis chilensis, which attacks a number of minor pest insects (DeBach and Rosen 1991). Both the 1874 aphid project and the 1889 cottony cushion scale project exemplify a hallmark of New Zealand biological control: intense, continuing interaction with similar programmes in other nations especially Australia, the United States, South Africa, and the United Kingdom. Such cooperation accelerates New Zealand projects and lowers costs not only by aiding collection and shipment of proposed natural enemies but by allowing New Zealand scientists to rely to an extent on tests performed in similar systems elsewhere (Fowler et al. 2000).

Several other introductions of predators and parasitoids of non-native pest insects have largely succeeded in minimising damage in New Zealand. By 1989, 225 species of natural enemies had been introduced targeting 70 pest species (most of them introduced). Of these 225, 70 species established populations and 24 achieved at least partial control of the target species (Cameron et al. 1989). For instance, the southern green stink bug (Nezara viridula), native to Africa and/or the Mediterranean region and a pest of many vegetable, fruit, and nut crops, was discovered in New Zealand in 1944; a wasp that parasitises its eggs was introduced in 1949 and quickly achieved substantial control (DeBach and Rosen 1991), while a parasitic wasp of its nymphs arrived by unknown means by 2010 and may further contribute to control (Martin 2016). An interesting recent New Zealand success is unusual for biological control because, in combination with other means (especially use of insecticides), it led to total eradication of a target introduced pest, the great white butterfly, Pieris brassicae (Klein 2016; Brown et al. 2019). Although insecticides were the main tool, a wasp was introduced that parasitised pupae of the butterfly, which were unaffected by the insecticide. Because the butterfly was a threat to native plants as well as agriculture, this eradication project was mounted jointly by the Department of Conservation, Horticulture New Zealand, and AgResearch.

A more recent development is major attempts to control plants that are either largely or partially environmental pests and not agricultural weeds (Fowler et al. 2000). A successful example is the control of North American mist flower (Ageratina riparia), a weed of many North Island habitats including wetlands and forest margins, by introduction of a smut fungus in 1998 and a gall fly in 2001 (Fowler 2016). A persistent concern with biological control in general is the extent of non-target impacts (Van Driesche and Simberloff 2016). Fowler et al. (2000) argue that these are minimal for biological control of plants in New Zealand, in line with more general dismissals of such concerns (e.g., Van Driesche and Hoddle 2017).

I believe these authors are overly defensive and thus unconvincing. Fowler et al. (2000, p. 557) assert that ‘Damage that is sufficiently severe to suppress populations of a non-target plant significantly will be obvious in a country like New Zealand’, citing the ‘vigilance of New Zealand observers.’ I am not so sure. For instance, the European gorse seed weevil (Exapion ulicis), introduced in 1931 to control gorse, one of New Zealand’s worst agricultural and environmental weeds, became one of the commonest insects in New Zealand (Fowler et al. 2000). Since then four other insect species and one mite species have been introduced and established populations (Hill et al. 2000, 2008), yet this entire complex has yet to control gorse (Hill et al. 2000). There has not been substantial research on what the six surviving species are doing in New Zealand, except that they are not adequately controlling gorse. Although I am greatly impressed by the pride in and attention accorded to native biota by New Zealanders, both Māori and Pākehā (see below), I am far from certain that even important impacts of these arthropods on all of 2,300 indigenous plants would be noticed and recognised as caused by one or more of these arthropods.

New Zealand is seen as the nation with the most comprehensive and fair system for permitting proposed introductions, including biological control introductions, and has introduced substantial oversight to ensure the safety of such introductions and to allay concerns of stakeholders (Barratt et al. 2018). New Zealand is the only country in which classical biological control proposals undergo a review that can be termed open, informed, and democratic (Blossey 2016). The Hazardous Substances and New Organisms (HSNO) Act of 1996 created an Environmental Risk Management Authority (ERMA; now EPA-NZ) to regulate all novel organisms (including planned introduced species) and hazardous substances (Warner 2016). EPA-NZ requires petitioners seeking to introduce species to provide evidence of risk, benefits, and public consultation. The risks and benefits are mandated to be based on a transparent risk/cost-benefit analysis (Barratt 2011), and all applications and decisions are posted on the internet. Importantly for biological control, scientists conducting research on agents for potential release are not petitioners; rather, a land management agency or organisation is, removing scientists from potential conflicts of interest. Further, concerned citizens may speak directly to EPA-NZ. Almost all of these features contrast strongly with permitting and public notice aspects of biological control in the United States (Warner 2016). Importantly, host-specificity of proposed biological control agents, although not a requirement, quickly became a standard for permit approval.

Interestingly, biological control practitioners globally complain of being needlessly subjected to increasing regulation, largely in the name of environmental protection, and argue that this trend is already decreasing the size and scope of biological control programmes in general and particularly in the service of conservation (Blossey 2016; Barratt et al. 2018). Barratt et al. (2018) produce data showing the discipline in decline (notably except in New Zealand and South Africa) and suggest that risk aversion, especially of harmful non-target impacts, long delays posed by empirical tests of non-target impact, and failure to account adequately for benefits are the bases of the decline. The fact that New Zealand has a thriving biological control community despite the imposition of a widely admired yet stringent regulatory process causes me to doubt that appropriate regulation needlessly impinges on biological control. New Zealand alone has a maximum statutory period (100 working days from receipt of the application) for a decision to be made, but presumably the need to demonstrate low likelihood of non-target impacts causes petitioners to have done substantial testing before submitting a petition.

New Zealand also leads in another technology for managing non-native species: setting aside areas on the main islands, surrounding them with a more or less elaborate fence that excludes invaders (see above), clearing them of invaders, then maintaining and possibly enlarging the fence to produce reserves for native species that would otherwise be threatened (Burns et al. 2012; Innes et al. 2019). The technology builds on the previously initiated strategy of unfenced ‘mainland islands’ in which predator removal and other intensive operations would aim to control but not necessarily eradicate invasive species as part of full-scale ecological restoration (Saunders and Norton 2001). The largest of the more recent fencing projects is Maungatautari, a mountain and surrounding area of 3,400 ha in New Zealand from which 14 introduced mammals have been removed and excluded by a 47 km-long fence, leaving only the house mouse (Mus musculus; Innes and Saunders 2011). Several species threatened by the excluded mammals, such as the takahe (Porphyrio hochstetteri), have been introduced to the site. In addition to other New Zealand mainland islands and peninsula-fenced sanctuaries (Innes et al. 2019), a similar project is now underway in the Hawaiian Islands to exclude feral pigs (T. Menard, pers. comm. 2017).

I will close this section on managing invasions by pointing to the globally inspiring Predator-Free 2050 project announced in 2016. The fact that it united the public, NGOs, philanthropists, and the government in a vision that eliminating non-native mammalian pests can actually be achieved and is a desirable goal signals the vision and leadership of New Zealand in confronting the issue of invasions. Several papers in the Dundee conference (Veitch et al. 2019) address aspects of Predator-Free 2050, as is befitting for a conference with the subtitle ‘Scaling up to meet the challenge.’ Predator-Free 2050 is the most explicit, well-formed plan to achieve scaling up. Activities to develop the necessary tools to accomplish this job are well underway (Murphy et al. 2019). Further, the attention and controversies (cf. Bioethics Panel 2019; Peltzer et al. 2019) attending the announcement of this inspirational project have sharpened focus on the fact that it will entail more than simply scaling up technologies previously successful on smaller (and often uninhabited) islands and in particular will require close coordination of biological researchers and managers on the one hand and various stakeholders among the public (Peltzer et al. 2019). This type of coordination is a growing concern internationally as invasive species management, including eradication, addresses larger and more complex cases (Beever et al. 2019).

Extinction and the Lazarus effect

New Zealand is known for the staggering number of species that have disappeared since human colonisation. The several species of moa rank with the dodo (Raphus cucullatus), the solitaire (Pezophaps solitaria), the passenger pigeon (Ectopistes migratorius), and Steller’s sea cow (Hydrodamalis gigas) as famous species anthropogenically extinguished so recently that conservationists shudder at the loss and even dream of de-extinction through manipulation of ancient DNA. However, New Zealand is also recognised for having resurrected species from the threshold of extinction. The great majority of these basket-cases were threatened by introduced predators, often in combination with hunting and/or habitat destruction. Possibly the most famous example globally was the Chatham Island black robin (Petroica traversi), whose rescue was chronicled by Butler and Merton (1992). The rescues of the takahe and the kakapo (Strigops habroptilus; Young 2004), although not publicised as widely as that of the black robin, are certainly known globally to bird-lovers and many conservationists. An accessible account of the rescue of the kakapo is now also available (Ballance 2010). The tuatara (Sphenodon punctatus), because of its evolutionary significance, is well-known by many biologists and conservationists and even some of the ordinary public, so the struggle to save the tuatara by captive propagation, rat eradication, and translocation has garnered much attention. Although public interest in insect conservation is notoriously lower than interest in conservation of charismatic vertebrates (or even not-so-charismatic ones, like the black robin), weta species, because of their evolutionary significance and sheer size, are of wide concern at least to conservationists, so the extraordinary measures to protect various weta species from introduced predators are among the globally best known insect conservation projects.

Similar conservation rescues have occurred elsewhere and are still being undertaken. In the United States, for instance, the general public knows about the near-extinction, rescue, and continuing efforts to ensure long-term survival of the California condor (Gymnogyps californianus) and the whooping crane (Grus americana). Uniquely among nations, the United States also has an Endangered Species Act 1973 (ESA) that is intended to prevent populations from declining to the threshold of extinction and, if they nevertheless reach that state, mandates extraordinary measures to recover them (Schwartz 2008; Roman 2011). Although Republican Congresses and Presidents have tried for three decades to weaken its provisions, carve out exemptions, or hinder implementation, the ESA has largely survived intact and is credited with having saved many species from extinction, though no legendary case as dire as that of the black robin is among them. However, many listings and proposed recovery plans are contested, generally on economic grounds, including the claim that enforcing them will limit some sort of resource usage, and this is the aegis for the ongoing attempts to weaken the act. It is striking that the descriptions of New Zealand conservation ‘losers’ (Hare et al. 2019) occasionally list economic cost of needed measures as an impediment to success, but they do not include the vitriolic objections to recovery based on economic self-interest that are frequent in the United States. Perhaps if New Zealand had a single law analogous to the ESA under which all imperilled species management were conducted, the law itself and particular implementations would elicit this sort of response, but it may simply be the case that the public in New Zealand, having recognised the vast species loss described by Young (2004), is on the whole more supportive of conservation than in the United States.

Marine conservation and restoration

Towns and Ballantine (1993) pointed to the substantial global lag in marine conservation technology and research support relative to terrestrial analogs, and the disparity between marine and terrestrial conservation has, if anything, increased in the quarter century since their observation. In particular, if we consider ameliorating the impact of invasive species, New Zealand provides an excellent example of this disparity. New Zealand has variously recorded 61, 130, 152, and 179 established marine invasive species (Hayward 1997; Craig et al. 2000; Forrest et al. 2006; Hayden et al. 2009, respectively; the increase is likely partly attributable simply to the continuing arrival of invaders). Impacts of most of these invaders are unknown, but at least several (e.g., Crassostrea gigas; Hayward 1997) are likely substantial and ecologically harmful. Against the impressive and growing number of examples of eradication of terrestrial invaders depicted above, the paucity of marine eradications is striking. For instance, of the 95 papers and 45 abstracts in the 2011 eradication conference in Auckland (Veitch et al. 2011), not a single one dealt with a marine organism. In the 2017 conference in Dundee (Veitch et al. 2019) there is but one. This is not to say there have been no eradications of marine invaders, but in New Zealand and globally these are rare and usually restricted to narrowly distributed nearshore populations, often recently established. An inspirational partial exception is the eradication of the mussel Perna perna from a deep soft-sediment site in central New Zealand (Hopkins et al. 2011), and a few other noteworthy cases exist globally (e.g., the eradication of the Caribbean black-striped mussel Mytilopsis sallei in Australia [Bax et al. 2001] and the ‘killer alga’ Caulerpa taxifolia in California [Muñoz 2016]). The general impediments to such eradications are difficulty delimiting the target population and lack of adequate technology to attack it, but the three examples just cited suggest that acting quickly even in the absence of tested technology is crucial to success.

Neither has classical biological control, another technology for which New Zealand has historically played a leading role (see above), produced successful management of marine invaders. Both Lafferty and Kuris (1996) and Secord (2003) have pointed to characteristic differences between marine and terrestrial invasions and potential biocontrol agents, and they urge great caution in proposed marine biocontrol introductions. One concern, as with terrestrial biocontrol, is the potential effect on non-targets if the agent is not host-specific. Interestingly, one of the most heralded marine invasions, that of the Atlantic ctenophore Mnemiopsis leidyi in the Black Sea, has largely been controlled by another ctenophore, Beroe ovata, which was introduced by unknown means while under discussion as a potential biocontrol agent (Shiganova et al. 2004). Beroe ovata is certainly not host-specific, which counted as a strike against it during these discussions, but I have noted no objections since it has proven so effective against M. leidyi. A promising first attempt to use augmentative biological control (augmenting the population of a native enemy of an introduced species) in a marine setting targeted the Asian kelp Undaria pinnatifida at a site in Fiordland, New Zealand. It entails collecting native sea urchins (Evechinus chloroticus) and manually placing them in sites dominated by kelp and control sites lacking kelp (Atalah et al. 2013).

In the absence of technologies to eradicate or substantially control marine invaders, efforts in New Zealand and elsewhere on marine invasions have focussed on preventing invasion in the first place and identifying which species are most likely to invade, by what routes, and on what impact they might have (e.g., Forrest et al. 2006; Hayden et al. 2009), and suggesting that rapid-responses should be planned for high-risk invaders, but without actually developing the responses (e.g., Wotton and Hewitt 2004; Forrest et al. 2006).

Rather, the major New Zealand approach to marine conservation has not focussed on invasions at all. Instead, it has consisted of trying to minimise harvest and other activities that damage marine ecosystems. An effort led by Bill Ballantine has made New Zealand, with Australia and the United States, one of the global leaders in establishing marine reserves, especially ‘no-take’ reserves that exclude both recreational and commercial fishing as well as activities like dredging (Ballantine 1995, 2014; Ballantine and Langlois 2005, 2008). The Marine Reserves Act was passed in 1971. In the face of substantial opposition to virtually every addition to the system, the first New Zealand marine reserve (one of the world’s first) was established in 1975, and the network currently contains 35 no-take reserves and a variety of other reserves with various degrees of protection for particular groups of marine species (<https://www.wwf.org.nz/what_we_do/marine/marine_protected_areas2/>, accessed 2/5/19). Research and other data gathered from these protected areas and other sites show a great variety of beneficial conservation effects of the no-take reserves (Ballantine 2014) but several shortcomings of the current network (Ballantine and Langlois 2008; Ballantine 2014) – inadequate total area, insufficient representation of certain marine habitats, and insufficient replication of reserves in certain regions and habitats. Ballantine (2014) details responses to the various objections raised as the current network was established.

The government is currently considering replacing the Marine Reserves Act with a ‘Marine Protected Areas Act’ that would ‘aim to achieve an appropriate balance between protecting our marine environment and maximising commercial, recreational and cultural opportunities now and into the future’ (<http://www.mfe.govt.nz/marine/reforms/marine-protected-areas>, accessed 2/5/19). The goal of simultaneously maximising commercial, recreational, and cultural opportunities is of course impossible, and many of the objections to the existing impressive network were based on perceived limits on commercial and recreational opportunities in favour of environmental protection. So it is concerning that the necessary strengthening of the system outlined by Ballantine and Langlois (2008) and Ballantine (2014) is now subject to the same kinds of criticism, and the government appears responsive to it. There is particular concern that the proposed act will not adequately protect deep-sea sites.

Ecological restoration beyond removing invasive species

Restoration ecology is a relatively new science, until recently a rather disparate collection of ad hoc, site-specific projects lacking a conceptual framework (Suding 2011). A series of publications in the 1990s and especially the first decade of this millennium aimed to establish such a framework, and New Zealander David Norton coauthored perhaps the most cited article on conceptual foundations of the field as a subdiscipline of ecology (Hobbs and Norton 1996). Ecological restoration is now defined as the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed (SER 2002; Clewell and Aronson 2007), so it is explicitly focussed at the ecosystem level, with recovery of various ecosystem features and processes, especially resilience, the criterion for success (Suding 2011). Although removing or managing invasive species is often a key part of ecological restoration (Towns et al. 1990), it is not, in and of itself, ecological restoration, but rather a frequent prerequisite for other processes and phenomena (e.g., reintroduction of extirpated native species, recreation of native vegetation, reestablishment of certain ecosystem functions) that may not ensue without further active human intervention. Certainly a leader in the management of invasive species in the service of restoration, New Zealand is an active but not leading participant in the larger explosive growth of restoration ecology and its associated technologies.

One particular focus, unsurprising in such a heavily agricultural nation, has been agricultural ecosystems. Norton et al. (2013) identified and related the myriad threats posed by agriculture at the ecosystem level, and various particular technologies to counter those threats beyond simply removing invasive species have been improvised and tested – for example, leaf litter additions through enhanced riparian cover in agricultural catchments (O'Brien et al. 2017). Another New Zealand restoration focus has been restoring badly damaged urban ecosystems, a well-known long-term project led by Bruce Clarkson (Clarkson and Kirby 2016; Wallace and Clarkson 2019). An additional focus has been restoration of New Zealand’s wetlands and peatlands, an enterprise headed by Beverley Clarkson (e.g., Clarkson et al. 2017). Interestingly, in the wake of the inspirational Predator-Free New Zealand 2050 project discussed above, Norton et al. (2016) consider what restoration of New Zealand’s biological heritage by 2050 would entail beyond invader removal. They detail several increasingly standard restoration techniques (e.g., plantings of formerly extirpated or reduced plant species) and generally advocate aiming for ecosystem resilience. Particularly stressed is the need for engagement of Māori principles, values, and customs, in accord with recommendations by Lyver et al. (2019) discussed below.

The entire field of restoration ecology has recently been riven by a suggestion that, in many sites, ecological damage has been so great that restoration to a semblance of some original ‘native’ state is impossible and that a practical and laudable goal is instead creation of ‘novel ecosystems’, self-sustaining new collections of species that provide various ecosystem services to humans (Hobbs et al. 2013). This proposal has elicited vigorous disagreement (e.g., Murcia et al. 2014). It is striking that, beyond the presence of David Norton as one of 18 coauthors in an early manifesto (Hobbs et al. 2006) heralding the ‘new world order’ organised around novel ecosystems, New Zealanders have not been notable participants in this debate, although the discussion of appropriate goals for restoring New Zealand’s biological heritage by 2050 (Norton et al. 2016) points at times in this direction, focussing on the magnitude and frequent probable irreversibility in changes wrought on the New Zealand landscape.

Global impact of the legal framework

With amusement I noted Towns et al. (2019) repeat the assertion of Young (2004) that the world was ‘astonished’ at the passage of New Zealand’s Resource Management Act (RMA) in 1991. Some conservationists and environmentalists as well as experts in resource economics and law certainly noticed the RMA, and interest in it was aided by the fact that it stressed the concept of ‘sustainable management’, a bandwagon that had begun a few years previously with the Brundtland Report (World Commission on Environment and Development 1987) and that came, in the form of ‘sustainable development’, to dominate much environmental (but not conservation) thinking. However, it is difficult to believe that the RMA astonished the public or influenced or inspired legislation in other nations. As Craig et al. (2000) observe, the RMA can be viewed as countering the preservationist spirit of the Conservation Act of 1987, and they laud its emphasis on sustainability and the mandate to advance economic goals through use and development in addition to conservation. In fact, Craig et al. (2000) go so far as to anticipate the controversial advocacy of ‘novel ecosystems’, discussed above, as a suitable target for restoration.

Two New Zealand parliamentary acts did, however, strike a responsive chord internationally and continue to be seen as important steps towards a comprehensive legislative framework for conservation. Perhaps unsurprisingly, given the dominance of invasive species issues in conservation activities in New Zealand, these are the Biosecurity Act of 1993 and the Hazardous Substances and New Organisms (HSNO) Act of 1996, referred to above with regard to biological control. The Biosecurity Act was, to my knowledge, the first comprehensive legislation in any nation treating unintentionally introduced non-native species and, as such, attracted much attention internationally from the burgeoning invasion biology community as well as parts of the conservation community. The fact that it mandated a national pest management plan for species that contrived to enter New Zealand despite the exclusionary procedures laid out in the plan inspired similar ideas in U.S. President Clinton’s Executive Order 13112 1999 (Invasive Species), which called for an Invasive Species National Management Plan (Section 5) for federal agencies dealing with invasive species. Executive Order 13112 also established a National Invasive Species Council comprised of representatives of the major federal agencies dealing with invasive species, much as the Biosecurity Act sought to coordinate interactions among the various government agencies with responsibility for non-native species. The Hazardous Substances and New Organisms Act deals with planned introductions of non-native species – thus its relevance to biological control introductions discussed above. Because the same sorts of permitting issues were arising in other nations (not least the United States) as in New Zealand, the HSNO Act was also of great interest internationally, and not only to the biological control community. For instance, Naylor et al. (2001) called for it to be the global model for legislation governing aquaculture.

In the United States, Executive Order 13112 was superseded in the closing days of the Obama administration by Executive Order 13751 2016 (Safeguarding the Nation from the Impacts of Invasive Species), basically an attempt to remedy perceived weaknesses in Executive Order 13112. However, Executive Order 13751 still does not offer the same safeguards as the combination of the Biosecurity Act and the HSNO Act.

Finally, I have long admired the fact that New Zealand has a Parliamentary Commissioner for the Environment (PCE). I believe no other nation has a true analog to this office, a government entity whose duty and raison d’être is to be an independent watchdog over any other government entities and any matters relating to the environment. Certainly this is a more expansive role than the U.S. Environmental Protection Agency, which, contrary to its name, takes as its mission not being proactive and protecting the environment against anything perceived as threatening its well-being but rather enforcement of specific congressional acts, such as the Clean Water Act (1972) and the Toxic Substances Control Act (1976). I was particularly struck by the massive report ‘New Zealand under siege: a review of the management of biosecurity risks to the environment’ (PCE 2000a), which, i.a., outlined shortcomings of the Biosecurity Act and suggested improvements. The United States Congress formerly had an entity, the Office of Technology Assessment (OTA), that not only could undertake such a study but actually did, producing the influential report ‘Harmful non-indigenous species in the United States’ (OTA 1993). However, the OTA could undertake research only if commissioned by Congress to do so and was not an independent entity charged with determining what needs to examined and then doing the required research. In any event, Congress abolished the OTA in 1995, although congressional calls for its re-establishment are persistent (Tully-McManus 2019). Another PCE report that caught my attention was the timely study ‘Caught in the headlights: New Zealanders’ reflections on possums, control options and genetic engineering’ (PCE 2000b), which foreshadowed an enormous rise in concerns with sociological aspects of invasion management and the possible use of genetic engineering in management. Dearden et al. (2018) highlight both of these concerns specifically in a New Zealand context. Though the PCE is well known at least in global conservation circles, I am unaware that any other nation has been inspired to construct a similar government position.

Role of Māori in conservation

The intense interaction with and attachment of Māori to the local landscape constitutes what is known as a bioculture (Rozzi 2012), and globally biocultures are severely threatened by homogenisation, generated by the many facets of globalisation and aided by accelerating rates of biological invasions (Rozzi et al. 2019). Influenced by my reading of Young (2004), I had long thought of the Māori as successfully bucking this trend, as their views on the environment and conservation were specifically to be accommodated under the Treaty of Waitangi. Although Young describes early 20^th century friction between Māori and the government over restricting Māori customary use in newly designated reserves, he depicts conservation and resource legislation as increasingly accounting for Māori interests. Lyver et al. (2019) paint a considerably less sanguine picture, asserting that, in many ways, the relevant aspects of the treaty have largely not been implemented. As I am not a lawyer, I cannot assess whether their proposed partial solution of legal pluralism is feasible, and particularly how disagreements driven by differing worldviews, customs, and interests will be adjudicated or resolved.

It is striking that some of the same sorts of disagreements, especially over customary use by Native Americans of imperilled species, have arisen in the United States. In Florida, traditional Seminole rites incorporating hunts for the Florida panther (Puma concolor coryi), listed as endangered under the ESA, led to a famous lawsuit by the U.S. Justice Department targeting a Seminole chief, who claimed that both treaties and the U.S. Constitution allowed at least limited hunting of a listed species and that the Seminoles also wished to preserve the population (Shabecoff 1987); in the event, he was acquitted by a jury. There have been no further tests of the ESA listing of panthers by Florida tribes. Customary hunting of federally listed gray whales (Eschrichtius robustus) by the Makah Tribe in the State of Washington has generated a persistent, widely publicised controversy (Stevens 2017). The 1855 Treaty of Neah Bay gives the tribe the right to hunt the whale ‘in its usual and accustomed grounds and station.’ However, such hunts ceased voluntarily in the 1920s in the face of declining whale populations. The species was classified as threatened under the ESA in 1994, and in 1999 the tribe legally killed one. Since then, they have been denied permission to hunt them (although one was illegally killed in 2007), at least partly on the grounds that, since annual hunting stopped voluntarily in the 1920s, the hunt was no longer customary. In 2017 a federal circuit appeals court denied their 2015 application for a permit, a bitterly resented decision.

Native Hawaiians have traditionally hunted introduced pigs, but as non-native species, pigs were to be removed from Hawaiian national parks under a clearly enunciated 1968 policy of the U.S. National Park Service. However, local park directors long temporised at implementing the policy, acceding only in the late 20^th century (Simberloff 2017). Finally, in Canada’s Haida Gwaii (Queen Charlotte Islands), the Native American Haida tribe deplores black-tailed deer (Odocoileus hemionus), introduced in 1911 for sport hunting by the British Columbia Game Commission (Golumbia et al. 2008), especially because the deer devastate traditionally used groundcover plants (Engelstoft 2002). However, the possibility of eradicating the deer has only recently been entertained (Bellis et al. 2019), because the Anglo-Canadian hunters resident in the islands prize the deer as game.

It is striking that in the United States and Canada indigenous customary uses appear to rank distinctly second in importance to laws and concerns of the wider community. Although Māori customary use and general environmental views have not carried much force against both conservation and development initiatives in the past, it is evident that at least there is widespread current recognition of a need for a more equitable interaction between the Māori and Pākehā. Notably, the panel convened to address social, cultural, and ethical challenges generated by Predator-Free New Zealand included Māori panelists and emphasized the importance of Māori engagement throughout the implementation of the project (Bioethics Panel 2019).

Conclusion

I have long been impressed by the leading role in invasion science, management, and policy played by a nation of only 4.7 million citizens and questioned what drives this national concern with both invasions and conservation in general. Surely the strong Māori association with the landscape and native species must have something to do with it, combined with the fact that the Māori have more successfully commanded respect from the colonial invaders and their successors than have other indigenous peoples.

Young (2004) points to another possible driver – New Zealand nature as an aspect of national pride that developed as a reaction to an English sense of superiority in the late 19^th century. Certainly this was the period during which widespread concern with environmental destruction, native species loss, and invasions by non-natives species arose. Young notes as a symbol of this growing pride the replacement in 1901 on penny postage stamps of Queen Victoria by depictions of Mount Cook and Lake Taupo.

Finally, I have observed (Simberloff 2006) that biological invasions as an important phenomenon to be countered were first widely recognised in Australia, New Zealand, South Africa, and the United States. Europe in general joined the explosion of interest in combating invasions about a decade after the above-mentioned countries, except for the United Kingdom, which joined the fray early (in fact, much of the activity of Elton’s Bureau of Animal Population at Oxford University consisted of studying and attempting to manage animal invasions of the United Kingdom). Thus there is perhaps something about an anglophone/English background conducing to development of concern with invasions, and with conservation generally, and the New Zealand history is at least partly an example of this English influence. Surely embedded in this conjecture is a subject worthy of a doctoral dissertation.

Acknowledgments

I thank David Towns, Charles Daugherty, and James Aronson for discussion of aspects of this manuscript. I am particularly indebted to David Young, who graciously handed me a copy of his highly informative book soon after publication, at a meeting on conservation in New Zealand.

Disclosure statement

No potential conflict of interest was reported by the author.