We developed the DAMA (Distribution of Alien MAmmals) database, a comprehensive source reporting the global distribution of the 230 species of mammals that have established, self-sustaining and free-ranging populations outside their native range due to direct or indirect human action. Every alien range is accompanied by information on its invasion stage, pathway, method of introduction and date of introduction. We collected information from 827 different sources (scientific literature, books, risk assessments, reports, online biodiversity databases and websites), and used it to draw alien range maps for these species following the IUCN mapping framework. DAMA comprises 2726 range polygons, covering 199 Countries, 2190 level 1 administrative areas and 11 zoogeographic realms for the period 21500 BC-AD 2017. The most Accepted ArticleThis article is protected by copyright. All rights reserved represented orders among introduced mammal species are Rodentia (n=58, 25.22%), Cetartiodactyla (n=49 species, 21.30%), Carnivora (n=30 species, 13.04%), Diprotodontia (n=28, 12.17%) and Primates (n=26, 11.30%). Mammal species have been frequently introduced for hunting (n=100), pet trade (n=57), conservation (n=51) and fauna improvement (n=42). The majority of range polygons are placed on islands (n=2196, 80.56%), encompass populations that have moved beyond establishment and into the invasion stage (n=1655, 60.71%), and originated from 1500 AD to the present (n=1496, 54.88%). Despite inheriting literature biases towards more studied regions (e.g., developedCountries), DAMA is the most up-to-date picture of alien mammal global distribution and can be used to investigate their invasion ecology across different biogeographical regions. There are no copyright or proprietary restrictions; IUCN range maps were modified into a derivative work according to the IUCN's terms of service.

1. Biological invasions have emerged as one of the main drivers of biodiversity change and decline, and numbers of species classed as alien in parts of their ranges are rapidly rising. The European Union established a dedicated regulation to limit the impacts of invasive alien species (IAS), which is focused on the species on a Union List of IAS of particular concern. However, no previous study has specifically addressed the ecology of invasive alien mammals included on the Union List. 2. We performed a systematic review of published literature on these species.We retrieved 262 publications dealing with 16 species, and we complemented these with the most up-to-date information extracted from global databases on IAS. 3. We show that most of the study species reached Europe as pets and then escaped from captivity or were intentionally released. On average each year in the period 1981-2020, 1.2 species were recorded for the first time as aliens in European countries, and most species are still expanding their alien ranges by colonising neighbouring territories. France is the most invaded nation, followed by Germany, Italy, and the Russian Federation, and the muskrat Ondatra zibethicus, the American mink Neovison vison, and the raccoon dog Nyctereutes procyonoides are the most widespread species, having invaded at least 27 countries each. Invasive mammals of European Union concern are threatening native biodiversity and human well-being: worryingly, 81% of the 16 study species are implicated in the epidemiological cycle of zoonotic pathogens. 4. Containing secondary spread to further countries is of paramount importance to avoid the establishment of new populations of invasive mammals and the related impacts on native communities, ecosystem services, and human health.

While the regional distribution of non-native species is increasingly well documented for some taxa, global analyses of non-native species in local assemblages are still missing. Here, we use a worldwide collection of assemblages from five taxa - ants, birds, mammals, spiders and vascular plants - to assess whether the incidence, frequency and proportions of naturalised non-native species depend on type and intensity of land use. In plants, assemblages of primary vegetation are least invaded. In the other taxa, primary vegetation is among the least invaded land-use types, but one or several other types have equally low levels of occurrence, frequency and proportions of non-native species. High land use intensity is associated with higher non-native incidence and frequency in primary vegetation, while intensity effects are inconsistent for other land-use types. These findings highlight the potential dual role of unused primary vegetation in preserving native biodiversity and in conferring resistance against biological invasions.

Biological invasions have emerged as one of the main drivers of biodiversity change and decline, and numbers of alien species are rapidly rising. The European Union established a dedicated regulation to limit the impacts of invasive alien species (IAS), which is focused on a Union List of IAS of particular concern. However, no previous study has specifically addressed the ecology of invasive alien mammals included in the Union List.We performed a systematic review of published literature on these species. We retrieved 262 studies dealing with 16 species, and we complemented these with the most up-to-date information extracted from global databases on IAS.We show that most of the study species reached Europe as pets that escaped from captivity or were intentionally released. On average, 1.2 species’ new first records/year were documented in European countries in the period 1981-2020, and most species are still expanding their alien ranges colonising neighbouring territories. France, Germany, Italy, and The Netherlands are the most invaded nations, and the muskrat (Ondatra zibethicus), the raccoon dog (Nyctereutes procyonoides), and the American mink (Neovison vison) are the most widespread species, having invaded at least 27 countries each. Invasive mammals of European Union concern are threatening native biodiversity and human well-being: worryingly, 81.3% of the study species are implicated in the epidemiological cycle of zoonotic pathogens.Containing the secondary spread to further countries is of paramount importance to avoid the establishment of new populations of invasive mammals and the related impacts on native communities, ecosystem services, and human health.Our results offer the most updated compendium on the ecology of invasive mammals of European Union concern, that can be used to assist environmental policies, identify and subsequently fill knowledge gaps, and inform stakeholders.GRAPHICAL ABSTRACTGraphical abstract: Invasive alien mammals of European Union concern.The figure illustrates how the introduction of a species in few new areas, followed by a lag phase of adaptation and sometimes enriched by further subsequent releases, can rapidly lead to the colonisation of large parts of a continent. On the top left, a heat map with species’ richness in countries of Europe. On the top right, a word cloud with the main keywords of our literature search and some of the study species’ names. On the bottom left, four out of 16 study species: in clockwise order, the raccoon dog (Nyctereutes procyonoides), the muskrat (Ondatra zibethicus), the American mink (Neovison vison), and the raccoon (Procyon lotor). On the bottom right, the temporal distribution of the first records of the study species in the countries of Europe.

Ecological Niche Models (ENMs) are often used to project species distributions within alien ranges and in future climatic scenarios. However, ENMs depend on species-environment equilibrium, which may be absent for actively expanding species. We present a novel framework to estimate whether species have reached environmental equilibrium in their native and alien ranges. The method is based on the estimation of niche breadth with the accumulation of species occurrences. An asymptote will indicate exhaustive knowledge of the realised niches. Possible outcomes of the framework include: (1) There is enough data to quantify the native and alien realised niches, allowing us to calculate niche expansion between the native and alien ranges, also indicating that ENMs can be reliably projected to new environmental conditions. (2) The data in the native range is not adequate but an asymptote is reached in the alien realised niche, indicating low confidence in our ability to evaluate niche expansion in the alien range but high confidence in model projections to new environmental conditions within the alien range. (3) There is enough data to quantify the realised native niche, but not enough knowledge about the alien realised niche, hindering the reliability of projections beyond sampled conditions. (4) Both the native and alien ranges do not reach an asymptote, and thus few robust conclusions about the species’ niche or future projections can be made. We demonstrate the CNA framework for 26 species of mammals, amphibians, and birds. Our framework can be used to detect species’ environmental equilibrium in both the native and alien ranges, to quantify changes in the realised niche during the invasion processes, and to estimate the likely accuracy of model projections to new environmental conditions.

The Common Agricultural Policy (CAP) is the European Union's main instrument for agricultural planning, with a new reform approved for 2023-2027. The CAP intends to be aligned with the European Green Deal, a set of policy initiatives underpinning sustainable development and climate neutrality in the EU, but several flaws cast doubts about the compatibility of the objectives of these two policies. We reviewed recent literature on the potential of CAP environmental objectives for integration with the Green Deal: protection of biodiversity, climate change mitigation and adaptation, and sustainable management of natural resources. We found the CAP lacks appropriate planning measures, furthering instead the risk to biodiversity and ecosystem services driven by landscape and biotic homogenization. Funding allocation mechanisms are not tailored to mitigate agricultural emissions, decreasing the efficiency of climate mitigation actions. The legislation subsidises farms making extensive use of synthetic inputs without adequately supporting organic production, hindering the transition towards sustainable practices. We recommend proper control mechanisms to be introduced in CAP Strategic Plans from each Member State, to ensure the EU is set towards a sustainable production and consumption path. These include proportional assignment of funds to each CAP objective, quantitative targets to set goals and evidence-based interventions, and relevant indicators to facilitate effective monitoring of environmental performance. Additionally, both the CAP and the Green Deal should maintain ambitious environmental commitments in the face of crisis, to avoid further degradation of the natural resources on which our production systems stand.

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