November 29, 2016

The aliens’ way of life and the secret of (invasion) success

What do mynas, cane toads, guppies, Pacific lionfish, ants and signal crayfish have in common? As it emerges from the new book published by the Cambridge University Press, Biological Invasions and Animal Behaviour, they share the “perfect” behavioural traits that make them successful invaders. They are only a selection of the many species used as examples and case studies of this volume edited by Judith S. Weis and Daniel Sol, which gathers together several contributions from scientists across the world, covering a broad range of disciplines. The purpose is to provide a comprehensive  overview of the benefits of adding behavioural perspectives in biological invasions, for example for understanding why some species are more likely than others to succeed in a new environment, and also to foresee and analyse the relevant impacts.


The role of animal behaviour in facilitating the invasion process has probably been overlooked in the past, according to the editors. But in recent years scientists have been looking at the behaviour of alien species with growing interest.  As highlighted in the very inspiring volume edited by Weis and Sol, more emphasis is now put on the role of behavioural flexibility as a mechanism for succeeding across the various stages of invasion, i.e. from transport to impact. The study of animal behaviour, and how the cognitive process facilitates the invasion success, is key to understanding the factors which are supposedly influencing the likelihood that introduced species will establish and spread. For example, amateur aquarists know very well that it is almost impossible not to breed guppies. As pointed out by Andrea S. Griffin and colleagues, this is due to the very adaptable mating strategy of this tropical fish, also in novel environments. Guppies are very popular aquarium fish and are often released in the wild as unwanted pet release, or introduced intentionally for mosquito control, but opportunity alone would not be sufficient to explain their invasion success. Behavioural flexibility and remarkable plasticity in mating behaviour allow immediate adjustments in response to novel circumstances, thus it is not surprising to know that this species native to South America is now established in over 70 countries outside its native range.



Red swamp crayfish (Procambarus clarkii) © Photo: Riccardo Scalera

The recurring behavioural traits which favour the successful invasion of a number of alien species are discussed in detail throughout the 18 chapters of the book. Invasive alien crayfish are another example. As Elena Tricarico and Laura Aquiloni describe in their exhaustive review, many species belonging to this group are highly flexible and adaptable, able to display new and different behaviours in new habitats. They actively and widely disperse, and can avoid predation, even from new predators, thanks to their ability to respond adaptively to a wide range of predation risk cues. They are also characterised by flexible feeding habits (as they are usually omnivorous and voracious), aggressive behaviour, some hybridisation potential, and are highly prolific and able to identify mates also in challenging conditions (e.g. despite long distances and turbid waters).  Additionally, likewise many other groups of alien species, may even display personality traits that further enhance invasion abilities.


The book also emphasises the value to pay attention to how indigenous species are learning to live with the threat posed by invasive species. For example, a chapter by Ignasi Bartomeus and colleagues provides some useful insights on the role of behaviour flexibility and cognitive capabilities of pollinators in the process of adapting to novel environments dominated by alien plants.  Another fundamental contribution is the chapter by Martina Carrete and José L. Tella, who stress how the prevalence of some group of species over others in international trade (i.e. parakeets), suggests that the possession of particular traits may contribute to increase the likelihood of a species being traded. Here the point is the “attractiveness” (for people), although most species would not know much about etiquette and good manners (the perceived behaviour of most alien species would hardly fall into the category of socially acceptable and respectful).


However, this confirms the importance of human behaviour as a key driver of the movement of species outside their natural range, which explains the strong focus of the current nature conservation policies on the identification, prioritisation and management of alien species pathways. But, as already pointed out, this cannot explain why certain species or group of species are more successful than others in establishing self sustaining populations into new environments. Under a mere management perspective this evidence may have fundamental implications. As a matter of fact, while we may change our (human) attitude towards the problem, e.g. by introducing strong social norms to prevent further introductions, we need scientifically sound and reliable insights on alien species behaviour to define key management recommendations and direct future research on invasion biology. In this sense the book is a clear invitation to increase effort to focus future research activities on animal behaviour, and sheds new lights on the role of ethologists as key allies of conservation biologists.

November 14, 2016

Managing alien species pathways and vectors

Shipping and recreational boating, the movement of live bait and fire wood, cargo transport and wildlife trade, are only some of the pathways and vectors through which alien species are moved outside their natural range by humans. Transport, trade, travel and tourism provide vectors and pathways for live animals, plants, and other biological material to overcome those biogeographical barriers that would usually block their movement and spread. Given the multitude of such pathways and the variable impact they have, it is necessary to prioritize those pathways with the greatest impact on biodiversity and possibly manage them appropriately to enhance the prevention of biological invasions. 

Canada goose in "flight" © Photo: Riccardo Scalera

The importance of the threat of invasive alien species (IAS) pathways is reflected in a range of international, regional and national laws and agreements. For example, Target 9 of the Strategic Plan for Biodiversity 2011-2020 - adopted by the Convention on Biological Diversity (CBD) at the 10th COP - states: “By 2020, invasive alien species and pathways are identified and prioritized, priority species are controlled or eradicated, and measures are in place to manage pathways to prevent their introduction and establishment”. At the European level, the same goal is reported within target 5 of the Biodiversity Strategy to 2020 of the European Union (EU). As a result, all EU Member States, following the recent adoption of the EU Regulation on IAS, are required to develop action plans for the management of pathways: a significant improvement in the coordination, implementation, and consistency of pathway management across the region.

Also the Council of Europe provided significant support in this context. Since the development of the European Strategy on IAS in 2003, the Group of experts on Invasive Alien Species established by the Standing Committee to the Bern Convention in 1992,  has focussed its work on the identification and prioritisation of pathways, and started preparing targeted codes of conduct to address these. So far the Standing Committee has endorsed codes of conduct on IAS and activities such as horticulture, zoos and aquaria, botanic gardens, hunting, pets or recreational fishing (all codes are available here under documents/publications). Other codes are under development, including on plantation forestry and recreational boating. More recently, as reported by Recommendation N°179 (2015), the Bern Convention identified a number of activities to be carried out in coordination with the European Commission (EC), among which the possibility to draft a Guidance document on action plans for the management of IAS pathways.


The guidance document on IAS pathways action plans

The result is a document including three sections, namely an introduction (with an overview of the available information on identification, prioritisation and management of IAS pathways, along with preliminary results and future challenges on assessing priority pathways), a section describing the most relevant policy and legislation, and a core body including the actual guidelines on how to draft an action plan for dealing with IAS pathways. The following key sections of an ideal acton plan are described in the detail in the document of the Council of Europe:
  • Description of the target pathway
  • Policy and legal background
  • Aims and strategies
  • Identification of key stakeholders
  • Foreseen measures (Specific measures depending on the IAS  pathway targeted, Common measures for all management/action plans for IAS pathways)
  • Time schedule
  • Financial planning
Besides the elements of an ideal plan, the guidance document describes further elements to take into account for facilitating the management of the planning process, stressing the importance of a sound pre-planning phase.

Although the need of such guidance was inspired by the provisions of the EU regulation on IAS, the interest of this work is not to be considered limited to the EU Member States. This fits well with the Bern Convention role to further outside the EU the innovation of the EU Regulation on IAS, and represents another step in the process led by the Council of Europe in drafting key IAS related documents over the years, by stressing the added value of ensuring a harmonised approach in the region.

January 14, 2015

Protecting animal migration routes from biological invasions

Habitat destruction, climate change, unsustainable hunting and fishing practices, and barriers such as roads, power lines, dams, and wind farms, are some of the main factors affecting the conservation and sustainable use of migratory animals and their habitats. The Convention on the Conservation of Migratory Species of Wild Animals (CMS) is a framework treaty specialized in the conservation of migratory species, their habitats and migration routes, through a number of global and regional agreements focusing on specific topics and implemented throughout the migratory range of the target species (those that need or would significantly benefit from international co-operation). Invasive alien species (IAS) are another major threat to migratory species, and it is expected that following the adoption - at the 11th Meeting of the Conference of the Parties (held in Quito, on 4-9 November 2014) - of Resolution 11.28 on “Future CMS Activities related to Invasive Alien Species” they will be receiving greater attention from the CMS. The resolution is based on the results of a technical report commissioned by the UNEP/CMS titled “Review of the Impact of Invasive Alien Species on Species protected under the Convention on Migratory Species (CMS)” undertaken by the IUCN/SSC Invasive Species Specialist Group (ISSG), whose key findings are briefly presented below (a former version of the report is available here).

Free-flying colony of sacred ibis in a zoo in Northern Italy © Photo: Riccardo Scalera

According to the study over one third of species included within the CMS appendixes are under some level of threat from IAS, with seabird and marine turtle populations in their breeding/nesting grounds on island ecosystems being most under the threat of IAS. In total, 78 IAS have been recorded as having some measure of impact on CMS listed species, e.g. through predation, competition and genetic changes caused by hybridization, as well as through the transmission of diseases, impairment of breeding and by causing loss of habitat and resources crucial for migratory species. The top ten IAS include introduced mammal predators - such as cats, rats, dogs, pigs, and house mouse - and introduced herbivores - such as European rabbits, goats and domestic livestock. The spread of invasive alien plants, such as grasses and macrophytes, are another cause of habitat alteration and loss, as they may alter habitats of bird species through competition and displacement of native plants. An example is the intentional introduction of ornamental and “useful” plants such as the ironwood (planted for erosion control and as wind breaks along coastland), which is also known for its impacts on dune ecosystems, on native dune plants and nesting grounds of turtles. The spread of alien pathogens is also a serious threat to migratory species. For example migratory bird species especially waterfowl, shorebirds and gulls are both victims and vectors of the highly pathogenic avian influenza. Interspecific hybridisation is a concern among sturgeon populations.

The sacred ibis: a conservation paradox © Photo: Riccardo Scalera

The risk of migratory species to become invasive themselves if translocated and/or introduced outside their natural range, can help understand the complexities which characterize the interactions between IAS and threatened migratory species. For example, the sacred ibis, a native to Sub-Saharan Africa and the Middle East, is a kind of “conservation paradox” for although it is protected by the CMS, outside its native range is considered a threat to other species, including those protected by the CMS itself. In Europe, where breeding populations of this intra-African migrant are known in Spain (including the Canary Islands), France and Italy, the sacred ibis has been recorded as predating eggs and affecting seabird colonies of sandwich terns, common terns and black terns, all CMS appendix II species. There are other CMS listed species introduced outside their native range, which could represent a threat for the native biodiversity. Examples are the beluga whale and the grey seal, introduced outside their native range in the Black Sea (which are CMS Appendix II species, see previous post here), although no specific impacts have been recorded as yet.

An analysis undertaken to identify gaps and synergies of current policy initiatives in relation to IAS, showed that the inadequate action related to the management of IAS is not a result of gaps in international policy but rather it is caused by inadequate enforcement at national level. A more systematic cooperation between different global conventions and multilateral environmental agreements would definitely provide greater and more effective opportunities to address biodiversity issues, including those measures to prevent the introduction and spread of the most harmful species. In this context, key recommendations of CMS Resolution 11.28 include the improvement of understanding of interactions between IAS and threatened migratory species; the development of priorities for intervention; the improvement in international cooperation and the development of adaptable management strategies (including prevention, control, eradication, etc.) when discussing topics for which IAS might be relevant. Other fundamental provisions focus on the need to avoid policies and initiatives that limit the use of effective measures to eradicate or control IAS (or facilitate their introduction and further spread); the importance to take into account the risk of facilitating the introduction or spread of IAS while implementing any climate change mitigation or adaptation measures; the identification of potential strategic partners and relevant stakeholders for developing information campaigns and other outreach activities; and of course the mobilization of appropriate resources for the implementation of the measures directed at dealing with IAS issues in relation to migratory species.

December 15, 2014

The "birds" may have the right but the cat has the claws

The tale of Stephens Island wrens, driven to extinction by a single cat owned by the local lighthouse keeper, has become a very popular legend among conservationists. The true facts behind this legend are not very different, as this unique nocturnal, flightless bird which lived nowhere else on the planet, was apparently exterminated by feral cats, although more than a single one. In fact, in Stephens Island cats became established in 1894, and after increasing in numbers dramatically affected several species. Stephens Island provides the classic example of the effect that predation by feral cats can have on an island land bird fauna. But this is a problem of global concern. In New Zealand, like in several other countries worldwide, islands experienced a rapid demise of the native land bird fauna due to cat predation. With just a little more care, and a thorough knowledge and understanding of the problem, many islands may have remained a safe haven for many species now disappeared. In this context, a new book published by Wiley "Free-ranging cats. Behavior, ecology, management" (by Stephen Spotte) provides a comprehensive and objective insight on the key topics related to the management of feral cats, addressing some fundamental issues for a correct analysis of the problem, including a review of the available information on the species' behavioral, biological and ecological features. The message is clear: we should stop further irreversible biodiversity losses due to cat predation, and we have the proper knowledge to deal with it. The book represents an optimal guidance tool for all those who are interested in a sound understanding of the issue, whether the focus be on cats or the wide range of little animals they prey upon, or both.




Cats are generalist predators that once introduced to the wild (or simply allowed to roam outdoor), can prey on a variety of native species, which may suffer severe population declines and even face extinction. On this regard, it makes no difference whether the cats are owned (in which case their impact might be even more subtle, because often unnoticed), stray or feral: as stated by George F. Will (American journalist, and author) The phrase "domestic cat" is an oxymoron. The result is that at the global level, cats are considered responsible for at least 14% of bird, mammal and reptile extinctions and are the principal threat to almost 8% of critically endangered birds, mammals and reptiles. The figures are impressive. In continental Australia and its offshore islands there are some 15-23 million feral cats which are estimated to eat about 75 million native mammals, reptiles, birds and even insects a night, more than 20 billion every year (see here for details). These astonishing figures are very similar to the results of a study made in the US. Also in Britain, estimates derived from scaling up local studies to the national level show that cats kill 25–29 million birds per year. It is easy to imagine how detrimental this species can be, considering that cats have been introduced to about 179,000 islands worldwide. According to another recent study, the impacts of feral cats is known from at least 120 different islands on at least 175 different species of vertebrates (25 reptiles, 123 birds, and 27 mammals), many of which are listed on the IUCN Red List. For example, in the Canary Islands, four species (one endemic bird — the Fuerteventura stonechat — and three endemic giant lizards) out of a total of 68 species (including invertebrates) identified as preys are considered threatened (for a review on the impact of cats and other invasive alien species, see the EEA technical report No 16/2012 discussed here). 


Stray cat in Rome © Photo: Riccardo Scalera

Cats are predators and are not to be blamed for this, but people and particularly cat owners could do more to prevent all this to happen. Prevention would be the most effective and easy option to ensure a reduced predation of cats on small mammals and birds (not to consider reptiles and amphibians, and a number of invertebrates) and raising awareness  should be a fundamental step in any nature conservation campaign. Otherwise, there is no doubt that the more effective way to prevent exacting such a heavy toll on native wildlife would be the implementation of policies to prevent the establishment of feral cats and their colonies in (semi)natural environments (see for example the Australian 2008 threat abatement plan predation by feral cats). This could save millions, if not billions, of birds and other animals, yet for many people might inevitably sound inconceivable. For those pet lovers who consider cats as family members, it may be difficult to believe that their companion pets may turn into such harmful threat to biodiversity. In fact, cat owners should make a special effort to acknowledge the problem and ensure keeping their pets indoors. Whenever this is not feasible, an alternative partial solution would be to fit cats with quick-release collars equipped with a bell or other deterrents (like bibs), which may significantly reduce predation rates on small mammals and birds (although cats can learn to silently stalk their prey anyway). 

The implementation of effective control measures on feral cats can be a challenging task. First of all, to maintain the necessary political/public support and funding, it is pivotal to consider humane, socially acceptable options, including ways to avoid or minimize methods that cause animal suffering or affect domestic cats, particularly for the inherent problems associated with the opposition of citizens and animal welfare groups. Disregarding the importance of these aspects might lead to the failure of the operations. In addition, some drawbacks have been reported in situations where cats have been removed without taking into proper account the presence of other introduced species (such as rabbits, rats or mice). The risk is that some problems linked to hyperpredation and predator release effect may create trophic cascades leading to rapid, landscape-wide ecosystem changes. It was the case of the removal of cats on the sub-Antarctic Macquarie Island, which resulted in a significant increase in rabbit abundance (formerly reduced by cat predation), which in turn led to substantial local- and landscape-scale changes in vegetation. Although this trophic cascade was predictable given the history of rabbit impacts via grazing on both this and other islands and was not entirely unexpected, its extent was not fully anticipated. This episode (see here for details) shows the importance of carefully assessing the risks of management interventions and planning for their indirect effects.

June 18, 2014

LIFE confirms financial support to alien species policy in Europe

On 18 June 2014 a new LIFE call has been launched, and invasive alien species (IAS) continue to be a priority issue for funding within the European Union (see previous post on the 2013 call here). The new LIFE Regulation, which establishes the EU financial Programme for the Environment and Climate Action, with a total budget set at 3.4 billion euro for the funding period 2014–2020, has been throughly revised. For example, the programme is now subdivided in the two sub-programmes Environment and Climate Action. Besides, to ensures both the necessary flexibility to achieve the LIFE Programme targets and objectives and the necessary stability for potential applicants to plan, prepare and submit proposals, a Multiannual Work Programme for 2014-17 has been adopted. 

LIFE aims at contributing to the achievement of the objectives and targets of the Europe 2020 Strategy, the 7th Union Environmental Action Programme and other relevant EU environment and climate strategies and plans. In this context, and as reported more in detail below, IAS are explicitly mentioned in the list of project topics implementing the environmental policy priorities under the three priority areas covered within the new "Environment" strand: environment and resource efficiency; nature and biodiversity; and environmental governance and information.  It is also worth remarking that now the newly revised programme – which is open to the participation of third countries and activities outside the EU - consists of a number of new categories of projects, including preparatory projects, integrated projects, technical assistance projects, capacity building projects. The project topics set in the multi-annual work programme refer to "traditional" projects in the Environment sub-programme. "Traditional" projects are indeed very similar to the old LIFE+ Nature, Biodiversity, Environment and Information projects, e.g. focusing on best practice, demonstration, pilot, and information projects. 

More in detail, within the  priority area “Nature and Biodiversity” the project topics which are given priority to contribute to Target 1 of the Biodiversity Strategy to 2020 to fully implement the Birds and Habitats Directives, thus under the Thematic priorities for Nature, include:
Projects targeting invasive alien species, where these are likely to deteriorate the conservation status of species (including birds) or habitat types of Community Interest in support of the Natura 2000 network 
Priority is also given to project topics focus on the implementation of Targets 2, 3, 4 and 5 of the Biodiversity Strategy to 2020, thus under the Thematic priorities for Biodiversity, such as:
Projects implementing actions targeting Invasive Alien Species (under Target 5 of the Biodiversity Strategy or in view of contributing to reaching the level of protection set out in descriptor 2 — Non-indigenous species of the Marine Strategy Framework Directive (1)) through actions testing and applying approaches aimed at:(a) preventing the introduction of invasive alien species, in particular by tackling pathways of unintentional introduction,(b) establishing an early warning and rapid response system, and(c) eradicating or controlling established invasive alien species on an appropriate spatial scale.
These projects shall address with their actions the three steps (prevention; early warning and rapid response; eradication/control) in a comprehensive framework, or, where one of the steps has already been addressed, their actions shall at least be clearly situated in a broader framework that links all three steps. They should be set up to improve existing — or introduce new — technical, administrative or legal frameworks on the relevant level; they should aim at preventing the broader establishment of IAS within the EU.
Finally, the project topics listed under the priority area "Environmental Governance and Information", include:
National and transnational awareness raising campaigns on invasive alien species (IAS) targeting the general public and key stakeholders including policy makers, businesses, and local, regional or national authorities.
LIFE projects focusing on IAS across the years (source: EEA report no.15/2012)

The experience of the last 20 years has shown that LIFE has been crucial to ensure the successful implementation of several activities focusing on IAS management and prevention, including new ways to address the wider IAS challenge (see "LIFE and alien species" report here). In fact, as shown in a recent report on biodiversity indicators (EEA report no.15/2012), both the number of LIFE projects funded and the relevant cost estimates have been markedly positive across the years. The relevant data have been used for the development of a set of response indicators, whose role should be primarily to track the measures being implemented to mitigate pressures and improve the state of biodiversity.  This trend has been interpreted as reflecting an increasing awareness of the IAS problem among EU institutions, wildlife managers, scientific institutions, and citizens, but could also indicate that within the EU, the problem with IAS is increasing.  

Thus, in the light of the recent developments regarding the EU regulation on the prevention and management of the introduction and spread of IAS, the new call and the overall novelties introduced within the new LIFE Regulation, are very welcome. In fact the new EU regulation on IAS seeks to address the problem in a comprehensive manner so as to protect native biodiversity and ecosystem services, as well as to minimize and mitigate the human health or economic impacts that these species can have. The IAS legislation now needs only to be formally approved by the Council of Ministers (see details here), and there is a clear need of dedicated financial resources for the implementation of the foreseen types of provision focusing on prevention, early warning and rapid response, and management.

For the 2014 call 132,8 million euro out of a total budget of 404,6 million euro are for nature and biodiversity only, including related governance and information. The deadline for submitting proposals is 16 October 2014. You can find further information, application forms and all official guidance documents here.

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