Guidelines for Eradication of Terrestrial Vertebrates:
a European Contribution
to the Invasive Alien Species Issue
Document established by
Mr Piero Genovesi, Ph.D.
IUCN/SSC Invasive Species Specialist Group
National Wildlife Institute Italy Guidelines for Eradication of Terrestrial Vertebrates:
a European Contribution
to the Invasive Alien Species Issue Compiled by:
Piero Genovesi, Ph.D.
Co-ordinator European Section
IUCN/SSC Invasive Species Specialist Group
National Wildlife Institute – Italy
The European level: activities carried out under the Bern Convention 4
Scope of the present report 5
Coherence with other international guidelines 6
GUIDING PRINCIPLES FOR A EUROPEAN STRATEGY TO ADDRESS INVASIVE ALIEN SPECIES 7
Management of introduced alien species 9
International communication and co-operation 11
PLANNING AN ERADICATION 11
Selection of target species 11
Defining desired outcomes 12
Assessing feasibility 13
CONCLUSIONS AND RECOMMENDATIONS 20
Guiding Principles for a European Strategy to Address Invasive Alien Species 20
Guidelines for eradications of terrestrial vertebrates 21
CITED LITERATURE 23
BOX 1: The Global Invasive Species Programme 25
BOX 2: Threat from the Ruddy Duck in Europe 25
BOX 3: Eradication of the Grey Squirrel in Italy: Failure of the Programme and Future Scenarios 27
BOX 4: Eradication of alien micromammal species from island ecosystems 28
BOX 5: Mink eradication projects in northern Europe 31
The preparation of the present report was made possible by the co-operation of several governments, institutions, and experts. I thank the Minstry of the Waloon Region (Belgium) and the government of Switzerland for having contributed to the financing of this activity within the framework of Bern Convention. Mick Clout, chair of the IUCN/SSC Invasive Species Specialist Group, strongly supported the work. Dick Veitch had a fundamental role in permitting communication among experts through the aliens list he runs. Ana Isabel Queiroz provided invaluable support. Rüdiger Wittenberg supplied information on the results of the GISP programme. Giovanni Amori, Alessandro Andreotti, Nicola Baccetti, Simon Baker, Sandro Bertolino, Bruce Coblentz, Maj De Poorter, Palli Hertsteinsson, Baz Hughes, Fred Kraus, Tiit Maran, Marion Massam, Petri Nummi, Michael Pascal, Paulo Jorge Oliveira, Jorge Fernandez Orueta, Antonio Preziosa, Rod Randal, Wendy Strahm, and Paula Warren provided information and comments on the very different aspects related to the general issue of biotic invasions and the planning of eradication projects. Sandro Bertolino, Maj De Poorter, Petri Nummi, Ana Isabel Queiroz, Dick Veitch, Paula Warren and Rüdiger Wittenberg provided useful comments on a previous draft of the report. I apologise if I forgot to include any person who helped me in this work.
Invasive alien species (IAS) are now acknowledged as one of the major threats to biodiversity, together with habitat loss and fragmentation. Furthermore, it is predicted that biotic invasions will become the major engines of ecological disintegration in the future; this is because of the increased spread of alien species, due to the greater mobility of the human population, rapidly growing transport technology, expanding tourism and travel activities, and world-wide free trade (Cox 1999, Ruesink et al. 1995).
In addition to the threats to biodiversity, the direct costs of IAS are immense. It is difficult to estimate precisely the economic losses caused by biotic invasions, including the impact of weeds on crop production, the increased costs of control, the decreased water supply, the management costs of reducing the alterations of protected areas, the impact of introduced pathogens affecting wildlife and public health, and the impact of marine organisms transported by ballast waters. However, the costs likely exceed tens of billions of Euros annually (GISP 2000).Therefore, the planning of more effective strategies to deal with biotic invasions is a conservation priority on a global scale. For this purpose, the implementation of new actions at a national, trans-border and international level are required, based on a proactive rather than reactive approach.
The need to prevent and control introductions and the severe threats posed by biotic invasions have been repeatedly addressed at an international and regional level (see Shine et al. 2000 for a review).
In the last decade, the World Conservation Union (IUCN) also made invasive species a primary focus for its global action; the Species Survival Commission, supported by the Invasive Species Specialist Group, recently produced the “Guidelines for the Prevention of Biodiversity Loss caused by Alien Invasive Species” (IUCN 2000). Furthermore, the IUCN is a major partner of the Global Invasive Species Project (GISP), a coalition of scientists, economists, lawyers, social scientists, conservation and resource managers working together since 1997 to develop a new comprehensive strategy, that will lay the groundwork for new tools in science, education and policy through collaborative international actions. According to decision V.8 of the last COP of the Convention of Biological Diversity (CBD), the GISP will assist the Executive Secretary in the implementation of art. 8(h) (see Box 1).
The general concern of conservationists about the threats posed by biological invasions, and the general acknowledgement of the need and urgency to define and implement actions to reduce these threats, are faced with several obstacles. The major difficulty concerns the complex scientific, technical and political aspects involved, which include the sources of invasions, the pathways and modes of entry, the economic and emotional aims of intentional introductions, the methods to detect new invasions, the control techniques and their public acceptability, etc. In order to deal with biotic invasions, it is fundamental to address very different aspects, including international trade regulations, control during transport, border controls and quarantine, detection of new propagules, and public perception of the control methods. Furthermore, the generally very limited awareness of this threat by the public and decision-makers leads to inadequate participation and political commitment. IAS are a cross-cutting issue, which requires the co-ordination and commitment of several different sectors, as well as close co-operation between ministries with different responsibilities.
In synthesis, the key words for dealing with biotic invasions are: prevention, awareness and control. The purpose of the present report is to address the latter aspect, defining tools for eradicating invasive alien species once they are introduced into a new ecosystem. Nevertheless, it must be clear that control can only be effective if included in a coherent and comprehensive strategy. Biotic invasions represent the major challenge for conservation in the new millennium, requiring a holistic approach based on the efforts of governments, politicians, scientists and managers.
The European level: activities carried out under the Bern Convention
The Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention, 1979), with its 44 Contracting Parties in Europe, represents a powerful means to promote co-operation at the European level and in general to seek solutions to the threats posed by biotic invasions. Article 11 Paragraph 2.b of the convention refers to alien species: each Contracting Party has to undertake to strictly control the introduction of non-native species. The convention also includes other related provisions: Article 6, paragraph e, prohibits the internal trade of animals listed in Appendix II to the Convention; Article 7, paragraph 3, sub-paragraph c, deals with the regulation of transport of wild animals; Article 9, paragraph 1, fourth indent, refers to derogations permitted for purposes of re-population and re-introduction. Furthermore, the Standing Committee, which is responsible for overseeing the application of the Bern Convention, approved several recommendations suggesting procedures to reduce threats posed by invasive species, including:
No. 18, adopted in 1989, on the protection of indigenous crayfish in Europe;
No. 45, adopted in 1995, on controlling proliferation of Caulerpa taxifolia in the Mediterranean;
No. 57, adopted on 5 December 1997, on the introduction of organisms belonging to non-native species into the environment, requested Contracting Parties to prohibit such introductions;
No. 61, on the conservation of the white-headed duck (Oxyura leucocephala), noting the main threat to the long-term survival of the white-headed duck caused by the risk of hybridisation with the North American ruddy duck (O. jamaicensis), requested Contracting Parties and observer states to develop and implement without further delay national control programmes, which could involve eradication of the ruddy duck from all countries in the Western Palaearctic.
No. 77, adopted on 2 December 1999, on the eradication of non-native terrestrial vertebrates;
No. 78, adopted on 2 December 1999, on the conservation of the Red Squirrel (Sciurus vulgaris) in Italy, urged Italy to eradicate the invasive American Grey Squirrel (S. carolinensis).Since 1991, the Council of Europe, operating the secretariat of the Bern Convention, has made several efforts to support member states in the implementation of Article 11, Paragraph 2.b. In particular:
In 1992 a Group of Experts on legal aspects of the introduction and re-introduction of wildlife species was set up. This Group met on three occasions to review the legislation of Contracting Parties concerning this issue; a first report on Legal Aspects of the Introduction and Re-introduction of Wildlife species in Europe was published in 1992 (Isabelle Trinquelle T-PVS (92) 7). A second study on “Introductions of non-native organisms into the natural environment” was published 1996 (Cyrille de Klemm. Nature and Environment Series 73); the purpose of this study was to review the state of international law and of the national legislation of European countries concerning introductions, re-introductions and restocking and to present proposals aimed at strengthening national control mechanisms and enhancing the role of the Standing Committee.
In 1997 a report on “Introduction of non-native plant species into the Natural environment” by Jacques Lambinon, was published in Nature and Environment series No 87
In March 1998, the Bern Convention commissioned a report on “Methods to Control and Eradicate Non-Native Terrestrial Vertebrate Species”, compiled by Orueta and Ramos, which thoroughly analysed the methods for controlling and eradicating non-native terrestrial vertebrates, discussing their reliability, efficiency, selectivity and humanness in respect to the different taxonomic groups.
In 1999, the Bern Convention organised a workshop on the eradication of terrestrial vertebrates (Malta, June 3-9), where the experiences gained in Europe on such eradications were synthesised, circulated and discussed.
In relation to recommendation no. 61, the Bern Convention in 1999 promoted a study on “The Status of the Ruddy Duck (Oxyura jamaicensis) in the Western Palaearctic and an action plan for eradication, 1999-2002” (T-PVS/Birds (99) 9).
Scope of the present report
Despite the remarkable efforts to provide instruments for best management of invasive alien species, at present the implementation of eradication campaigns remains inhomogeneous at the European level. In some cases, the reasons for the gap between the available instruments and their concrete application include the deficiency of national strategies in some countries, limited public acceptance, and the often unclear decision lines.
The aim of the present paper is to help reducing these obstacles. In view of the need to integrate eradication campaigns into global and regional strategies on IAS, the report is organised in two parts. In the first part, the guiding principles for dealing with biotic invasions are reviewed, especially with respect to the planning of eradications. In the second part, guidelines for planning an effective eradication campaign are defined. With respect to the very comprehensive report by Orueta and Ramos (1998), which contains an up-to-date review of the available control methods, the present report will focus on the different aspects of the correct and effective planning of a control campaign, including biosecurity policies, repartition of roles and responsibilities, monitoring needs, and recovery of native species after eradication.
Patterns of arrival, establishment and spread of alien species, as well as methods for detecting new propagules and for controlling them, differ greatly among the main functional biological groups; in this regard, it was decided to focus the present report on terrestrial vertebrates which, although numerically negligible with respect to weeds and invertebrates, represent a major threat to several ecosystems.
Examples of such a threat are also reported in the annex to the recommendation no. 77 of the Bern Convention, where several cases of terrestrial vertebrates threatening European biodiversity are listed. They include: the risk of extinction of the white-headed duck, threatened by the introduced ruddy duck through hybridisation, the risk of extinction of the red squirrel (Sciurus vulgaris) through competition with the introduced American grey squirrel (S. carolinensis), the severe impact of the American mink (Mustela vison) through predation on both ground nesting birds and the water vole (Arvicola terrestris), and through competition with the endangered European mink (Mustela lutreola); the alteration of many vulnerable wetland ecosystems caused by the coypu (Myocastor coypus).
Furthermore, many European island ecosystems are particularly vulnerable to IAS, as confirmed by the impact of predation on nesting birds by introduced rats in many Mediterranean islands or by overgrazing by feral goats and rabbits. Rat, goat, rabbit and mink control programs carried out on several islands have proved to be extremely successful means to restore native biodiversity (see Boxes 4 and 5); priority should be given to the promotion of similar programs in the future.
The limited scope of the present report should not be interpreted as an under-evaluation of the impacts caused by non-vertebrate IAS. Invaders are present in all taxa, and definition of specific management tools to address invasions by all animal and plant groups is needed and should represent a follow up of the present work.
Coherence with other international guidelines
In view of the need for unequivocal terminology, coherent policies and co-operation among parties, particular attention has been paid to other guidelines developed at an international level. In particular, the terminology has been partly derived from the IUCN “Guidelines for the Prevention of Biodiversity Loss caused by Alien Invasive Species”.
The general principles have also been defined on the basis of the IUCN guidelines and of the GISP strategy, as synthesised in the Global Strategy for Addressing the Problem Of Invasive Alien Species, presented at the GISP synthesis meeting in Cape Town, 17-23 September 2000.
Finally, in the discussion of the technical aspects, the indications provided by the Toolkit of Best Prevention and Management Practices, prepared by Wittenberg and Cock within the framework of the GISP, have been thoroughly considered.
In the present report the following definitions of terms will be adopted:
“Invasive Alien Species” (IAS) means an alien species, subspecies or lower taxon which becomes established in natural or semi-natural ecosystems or habitats, is an agent of change, and threatens native biological diversity.
“Alien species” (non-native, non-indigenous, foreign, exotic) (AS) means a species, subspecies or lower taxon occurring outside of its natural range (past or present) and dispersal potential (i.e. outside the range it occupies naturally or could not occupy without direct or indirect introduction or care by humans) and includes any part, gametes or propagule of such species that might survive and subsequently reproduce (IUCN 2000).
“Biosecurity threats” means those matters or activities which, individually or collectively, may constitute a biological risk to the ecological welfare or to the well-being of humans, animals or plants of a country (IUCN 2000).
“Intentional introduction” means an introduction made deliberately by humans, involving the purposeful movement of a species outside of its natural range and dispersal potential. (Such introductions may be authorised or unauthorised.) (IUCN 2000).
“Introduction” means the movement, by human agency, of a species, subspecies or lower taxon (including any part, gametes or propagule that might survive and subsequently reproduce) outside its natural range (past or present). This movement can be either within a country or between countries (IUCN 2000).
“Native species” (indigenous) means a species, subspecies or lower taxon, occurring within its natural range (past or present) and dispersal potential (i.e. within the range it occupies naturally or could occupy without direct or indirect introduction or care by humans.) (IUCN 2000).
“Natural ecosystem” means an ecosystem not perceptibly altered by humans (IUCN 2000).
“Unintentional introduction” means an unintended introduction made as a result of a species utilising humans or human delivery systems as vectors for dispersal outside its natural range (IUCN 2000).
“Eradication” complete and permanent removal of all wild populations of a species from a defined area by means of a time-limited campaign (Bomford and O’Brien 1995, modified).
“Control” reduction of population density and abundance, in order to keep damage at an acceptable level.
“Containment” limiting the spread of a species by containing its presence within defined geographical boundaries (Bomford and O’Brien 1995).