Mediterranean versus Atlantic monk parakeets Myiopsitta monachus: towards differentiated management at the European scale.

BACKGROUND: The monk parakeet Myiopsitta monachus (Boddaert), native to South America, is an invasive species in several European countries, causing crop damage and potential negative impacts on wildlife. Only Spain and Great Britain have regulations to control monk parakeets, thus fast growth and spread of populations are likely to occur on a wide scale. The aims of this research are to update information on the distribution and population size of monk parakeets in Europe, assess whether differences in population growth or spread rate exist between populations, and provide recommendations to decision-makers. RESULTS: Our study estimates that there are 23 758 monk parakeets in the wild, across 179 municipalities in eight European Union (EU) countries; 84% of these municipalities hold between 1 and 100 monk parakeets. All countries with a representative historical record are experiencing exponential growth of monk parakeets. Mediterranean countries are experiencing higher exponential growth, spread rate and faster colonization of new municipalities than Atlantic countries. CONCLUSIONS: We recommend that EU Mediterranean countries consider declaration of the monk parakeet as invasive alien species of regional concern, and develop coordinated efforts to monitor and manage the species, taking advantage of the low population sizes in most municipalities. © 2019 Society of Chemical Industry.

Horizon scanning for invasive alien species with the potential to threaten biodiversity in Great Britain.

Invasive alien species (IAS) are considered one of the greatest threats to biodiversity, particularly through their interactions with other drivers of change. Horizon scanning, the systematic examination of future potential threats and opportunities, leading to prioritization of IAS threats is seen as an essential component of IAS management. Our aim was to consider IAS that were likely to impact on native biodiversity but were not yet established in the wild in Great Britain. To achieve this, we developed an approach which coupled consensus methods (which have previously been used for collaboratively identifying priorities in other contexts) with rapid risk assessment. The process involved two distinct phases: Preliminary consultation with experts within five groups (plants, terrestrial invertebrates, freshwater invertebrates, vertebrates and marine species) to derive ranked lists of potential IAS. Consensus-building across expert groups to compile and rank the entire list of potential IAS. Five hundred and ninety-one species not native to Great Britain were considered. Ninety-three of these species were agreed to constitute at least a medium risk (based on score and consensus) with respect to them arriving, establishing and posing a threat to native biodiversity. The quagga mussel, Dreissena rostriformis bugensis, received maximum scores for risk of arrival, establishment and impact; following discussions the unanimous consensus was to rank it in the top position. A further 29 species were considered to constitute a high risk and were grouped according to their ranked risk. The remaining 63 species were considered as medium risk, and included in an unranked long list. The information collated through this novel extension of the consensus method for horizon scanning provides evidence for underpinning and prioritizing management both for the species and, perhaps more importantly, their pathways of arrival. Although our study focused on Great Britain, we suggest that the methods adopted are applicable globally.