The Italian wall lizard: a conservation tale of a successful invader

If I could return as an animal, I'd like to be a lizard—an Italian wall lizard, you bet! Known to scientists as Podarcis siculus, this miniature, speedy dart of green is one of the world's most thriving and adaptable lizard species, and also a remarkably successful invader. Many introduced populations are now found far beyond their native range, which largely coincides with the Italian peninsula. Their global spread is often facilitated by humans, whether intentionally as pets or accidentally as hitchhikers on cars and trains. They can also be transported as contaminants alongside goods like building stones or nursery plants, particularly olive trees. Even the movement of Italian troops during the Spanish Civil War played a role in their introduction to Spain. But, as is often the case with alien species, once established outside their native range, they can quickly become a disruptive visitor that threatens local wildlife. Not surprisingly, some introduced populations of Italian wall lizards have been receiving increasing attention in recent years. A small population in Athens, Greece, was indeed eradicated a few years ago (mostly with the help of stray cats, for once a welcome ally of conservation biologists). Similarly, a few individuals were promptly removed at an early stage of introduction in Buckinghamshire, UK, and La Rioja, Spain.

Italian wall lizard introduced in Corsica
© Photo: Riccardo Scalera

However, the most interesting project targeting Italian wall lizards is taking place in the Aeolian archipelago in Sicily, Italy. The Aeolian Islands are a fascinating, arid group of small islands and rocks that emerged from volcanic activity in a beautiful corner of the Mediterranean Sea some 500 000 years ago. Here, the endemic Aeolian lizard (Podarcis raffonei) thrived until the introduction of the Italian wall lizard. The endemic species is now confined to three small rocky islets—Strombolicchio, La Canna, and Scoglio Faraglione—and a very small stretch of land on Vulcano Island, where the progressive expansion of the Italian wall lizard has cornered the remnant population. To combat this decline, expert researchers from a number of institutions, led by Roma Tre University, have launched the project LIFE EOLIZARD, co-funded by the European Commission, with many other partners including L'Aquila University, the Rome zoo (Bioparco), CNR and Triton.

A view to the Aeolian archipelago from Lisca Bianca
© Photo: Riccardo Scalera 

This ambitious project, aimed at halting and reversing the decline of this unique lizard, is structured around three main pillars: a) removing a threat to an endangered species, b) captive breeding of the endangered species, and c) reintroducing the endangered species. The introduced populations of Italian wall lizard on the two small islets of Lisca Bianca or Bottaro will be completely removed to turn them into a sanctuary for the reintroduction of the endemic Aeolian lizard. In parallel, Aeolian lizards are being successfully reproduced at both the Rome zoo (Bioparco) and a dedicated breeding center on Salina Island, making the release of hundreds of new lizards possible for recovery purposes. In this sense, EOLIZARD is a truly unique project that integrates the removal of an alien species with the reintroduction of a captive-bred population facing imminent extinction. This combination of measures is expected to increase the global population size by up to 140%, thus offering an unparalleled opportunity for the endangered Aeolian lizard to significantly boost its chances of survival. It is also worth mentioning that, in consideration of the human dimension, the invasive alien lizards are not killed but relocated to a nearby island where genetic analysis shows a sibling population already exists: thousands of little lizards will be gently captured by trained experts luring them into safe traps with some sweet juice, then quickly transported to the verdant island of Panarea and released into suitable habitats. This humane approach is one of the project's most innovative features.

Aeolian lizard captive bred at the Rome zoo (Bioparco)
© Photo: Riccardo Scalera

In a nutshell, EOLIZARD is exceptional because it operates as a living laboratory. This allows researchers to explore the ecological and evolutionary dynamics of both species and their ecosystems, including their relationship with human activity. Furthermore, comprehensive genetic analysis and health screenings performed on all animals provide a unique opportunity to understand population origins and the emergence of diseases, including potential zoonoses. The global significance of these efforts was widely recognized at an international workshop held in early June 2025 in Malfa, Salina Island, where world experts convened to share experiences on managing alien lizards and to discuss ideas for future research and collaboration. Insights shared at the workshop, drawing from a global dataset on lizard management, highlighted a critical hurdle: the lack of comprehensive reporting on management projects. 

EOLIZARD workshop participant
© Photo courtesy of Massimo Recupito (Triton)

Globally, approximately 20 species of invasive alien lizards are currently under some form of management, as highlighted at the EOLIZARD workshop. In Europe alone, where 50-70 species have been introduced or translocated outside their natural range within the region, the primary challenge with invasive lizards often comes from its own native Podarcis species. The Italian wall lizard for example is a remarkably successful and widespread invader, with established populations across much of Europe and beyond, including in Spain, Portugal, France, Switzerland, Greece, Croatia, Albania, Montenegro, Romania, Poland, Germany, Turkey, Tunisia, Libya, Azerbaijan, and the USA. The workshop's outcome was a clear call to action: we must develop effective methods for rapidly detecting and removing invasive lizard threats and, most importantly, implement measures to protect native species. In this context, the importance of the management and research activities carried out within the EOLIZARD project cannot be overstated. Never before has such an ambitious project been designed for a small lizard, neither in terms of the target alien population's size nor the area to be cleared. However, the project isn't without its risks. The complete removal of alien lizards could be quite challenging, especially when targeting the smartest or luckiest survivors, including newborns that may have escaped initial control efforts. Nevertheless, EOLIZARD has the potential to be a model for replication in many other areas.

This is a concrete example of the European Commission's conservation efforts. The Commission's approach is twofold: it aims to facilitate overall policy for alien species while also guiding local action. It achieves this by specifically funding innovative pilot, demonstration, and best practice projects through the LIFE programme, with the goal of encouraging beneficiaries to actively replicate and scale up the results. Furthermore, these efforts align with previous initiatives, such as the detailed management note for the Italian wall lizard. This note, also made for a number of other species, serves as an example of the measures needed to address threats from species that are native to some parts of the EU but invasive in others. These resources provide practitioners with crucial information on prevention, surveillance, rapid eradication, and long-term management. While the LIFE EOLIZARD project and the European Commission's mobilized resources are vital, the workshop's outcomes were clear: we must urgently improve data sharing, foster innovation in management techniques, and collectively raise the priority of addressing the subtle yet significant threat posed by invasive alien lizards. 

In the meantime, without stricter biosecurity measures, the Italian wall lizard will inevitably continue its global expansion. The lizard not only possesses all the ecological traits of a successful invader but is also actively supported by humans from around the world who enjoy having them sunbathing in their yards. So, as a take-home message, if you love Italian wall lizards as I do, don't take them with you abroad. Instead, just enjoy a visit to the Italian peninsula. You'll see plenty of them there and bring home great memories too!

The gateway to essential resources for biological invasions

Invasive alien species (IAS) pose a major threats to global biodiversity, as recently highlighted by the IPBES assessment, nevertheless 83% of countries globally do not have a legislation specifically dedicated to address invasive alien species. A notable exception is the European Union, where the policy framework to deal with biological invasions is relatively robust, particularly thanks to Regulation (EU) No 1143/2014. At the core of this legislation is a list of IAS of Union concern, which currently includes 88 species. This legislation has been always characterised by an inclusive and evidence-based approach to policy-making, thanks to the conspicuous work regularly carried out at the science-policy interface. Advancing scientific knowledge has been fundamental to both the shaping and implementation of the EU Regulation on IAS from the start. On the other hand, its enforcement has generated a vast amount of valuable data and information, relevant across diverse fields, from wildlife management and biology conservation to social science and humanities. 

Specifically, during the ten years of implementation of this legislation the European Commission has developed extensive resources - approximately 300 documents and tools - to support Member States to take action in a coordinated and effective way. These include, among the others, risk assessments, notes on measures and costs for the management of over 100 species, manuals for the management of vertebrates (including welfare issues), identification guides for field and customs (along with posters and cards for awareness raising purposes), reports on nomenclature and taxonomical issues, manuals for surveillance systems (including case studies), guidance for the interpretation of CBD pathway categories, pathway management analyses with a focus on e.g., ants, wasps, flatworms, as well as specific reports o soil, topsoil, use of chemicals, the role of alien species in the spread of zoonosis, etc. While many of these documents focus on the 88 species of Union concern (as well as species proposed for listing and many others), many have broader relevance, extending beyond Europe. 

Navigating this incredible amount of resources made freely available online by the European Union and related agencies, can be sometime challenging and requires some familiarity with the relevant webpages and portals. Here’s a guide to key starting points:

• Invasive alien species webpage of the European Commission. A good initial entry point for general information.
• Publications Office of the European Union. Its search function with relevant keywords will help to discover a wide range of documents. 

For a more comprehensive collection of readily accessible resources, the CIRCABC represents a crucial repository, which includes two separate primary libraries:

• Invasive Alien Species. Here it is possible to explore a moltitude of documents and reports collected in several folders.
• Scientific Forum on Invasive Alien Species. Particularly valuable for risk assessments made of species currently in the Union list, but also those which did not qualify or that are proposed and are being discussed by Member States.

Information on hundreds of projects on alien species management funded by the European Commission through the LIFE programme, along with the many outputs produced by each of them, can be found by exploring the online LIFE Public Database.

Another valuable resource is the EASIN website managed by the Joint Research Centre (JRC) of the European Commission, where it is possible to directly access a fair amount of resources. Besides hosting a number of useful technical documents, EASIN hosts data management platforms (EASIN catalogue, EASIN geodatabase), capacity-building resources, stakeholder engagement platforms, and more importantly NOTSYS - the European Alien Species Information Network Notification System - an extremely powerful tool aimed at facilitating notifications about new IAS observations and management measures in real time. 

Also the European Environment Agency (EEA) hosts some repositories with basic documents and tools: 

• Invasive Alien Species portal. This portal contains information related to the reporting under the EU Regulation on IAS, organised per species, country and aggregated data viewers.
• EIONET Central Data Repository  Here it is possible to find Member States reports on their work for the EU Regulation on IAS by searching by [country] >> European Union (EU) obligations >> Invasive alien species (1143/2014/EU).
• Reference portal for reporting under the IAS regulation. Here it is possible to find the instructions for Member States reporting and other resources. 

To easily access species-specific management notes and other similar documents, it is also possible to visit the IUCN webpage of external resources for invasive alien species.  

AI generated image (Gemini 2025)

In a world of complex and interconnected environmental challenges, biological invasions demand timely and coordinated action. The EU Regulation on IAS stands as a powerful tool in mitigating anthropogenic impacts. Its effectiveness, however, hinges on the availability and analysis of accurate, up-to-date information. Data, reports, monitoring systems, and scientific studies are not just supportive, they are foundamental pillars for targeted, transparent, and responsible environmental law implementation. A data-driven approach ensures precise interventions tailored to ecological needs, preventing ineffective or harmful decisions. The resources highlighted above, while not exhaustive, demonstrate the substantial body of knowledge dedicated to invasive alien species and the significant commitment of institutions like the European Commission in coordinating, developing, and disseminating vital tools and guidance for tackling biological invasions globally. 

New study offers hope for invasive hornets control

A 2024 study by Hassal and colleagues indicates promising developments in invasive hornet management and offers valuable insights for reassessing prevailing attitudes towards the warnings of ecological disasters from biological invasions (see details here). The main focus of the study - the yellow-legged hornet (Vespa velutina nigrithorax) - is an invasive species native to Asia, introduced in Europe over 20 years ago. Like other alien hornets, is a voracious predator of honeybees and other wild pollinators. Moreover like other hornets may pose a threat to human health. The study, funded by the European Commission to IUCN, highlights the importance of early detection and rapid eradication as a best option for successful management of this species and biological invasions in general. 

The yellow-legged hornet (Vespa velutina nigrithorax)
Drawing made by Massimiliano Lipperi © European Commission

It took about 10 years since the species was first detected in 2004 in France, before a comprehensive legislation would eventually be launched to address the multifaceted threats of biological invasions, specifically the EU Regulation no. 1143/2014 on invasive alien species. In the meantime, in the absence of adequate response action, the species got established not only in France, but also Italy, Spain, Portugal,  Switzerland, Germany, Belgium, the Netherlands, Luxembourg and Jersey. Moreover, scattered records were reported from Austria, Czechia, Hungary, Ireland, Slovakia, showing that the species may soon further expand its range to other countries.

The adoption of the EU Regulation on IAS has been key to start monitoring and slowing down the spread of this alien hornet. By means of modeling scenarios Hassal and colleagues have shown that the yellow-legged hornet could have spread even further if it hadn't been for the bulwark established by this benchmark legislation. The assessement of the potential extent of invasion by the yellow-legged hornet highlighted that if rapid eradication of early detections had not taken place, the species would have spread more rapidly particularly in Germany and the Netherlands (and in the UK, where early actions have allowed to prevent the spread of the species in the country). Based on environmental suitability for the species establishment and spread, the study also demonstrates the importance of the information collected in nearly real-time through NOTSYS,  the online system where EU Member States are required to notify early detections and rapid eradication measures regarding the yellow-legged hornet, along with any other alien species of Union concern. 

The control of the yellow-legged hornet in Belgium © Photo courtesy of Tim Adriaens

The advantages of a prompt action were further demonstrated by the recent eradication occurred in the United States of the northern giant hornet (Vespa mandarinia), actually the largest hornet in the world. It took only five years to declare this species native to Asia as extinct in the United States, where it was detected in 2019 (see details here).  This was a considerable relief for pollinators, which are already facing several challenges and didn't need another threat to deal with. And it was also an encouraging news for conservation biologists.

Nevertheless, it seems that new problems always arise: another species of alien hornets appeared on the horizon in the old continent. It is the case of the southern giant hornet (Vespa soror) recorded in Spain in 2022 (see details here). This is another aggressive predator originating from Asia, similar in size to the northern giant hornet (the one just eradicated from the United States), and which may have a huge impact on native wildlife, including several groups of invertebrates and well as small vertebrates, e.g. geckos, not to consider the potential health problems to people. Scientists advocating for urgent preventative measures toward new invasions of alien species are often dismissed as modern-day alarmist Cassandra. Despite their accuracy, predictions concerning the impact of invasive alien species - usually informed by documented evidence of ecological damage elsewhere - are often neglected. Yet, the evidence to address this potential new threat to biodiversity and human health as early as possible is unequivocal.

AI generated image (Google 2025)

You may infer from the examples above, it didn't take a Cassandra to foresee the potential consequences of such introductions, and that without prompt action the rapid spread of alien hornets across the entire continent would be inevitable. The Cassandra myth reminds us that scientists warnings of impending disasters are often unpopular and subsequently ignored. Might a more modern approach, such as consulting artificial intelligence (AI), prove more effective? We are just starting to rely on AI for surveillance measures, as shown by the example of the VespAI automated early warning system. It would be interesting to explore the warnings and advices that different AI platforms would provide in reply to the question: "What would happen if the southern giant hornet (Vespa soror) invaded Europe", and "Is it still possible to eradicate the southern giant hornet (Vespa soror) in Europe". The replies are unsurpringly clear and to the point, but also offer a clear window of opportunity ...Will AI eventually be regarded as a modern-day Cassandra, dismissed and ignored as well?