Non native species reported in the mountain range of the Pyrenees.

This checklist is the result of the compilation of non-native species reported in the Pyrenees according to the following inclusion criteria:

- Status. We included terrestrial and freshwater species considered non-native according to national checklists or regional atlases (FloraPyr, FaunaPyr). Species native to continental France or Spain were excluded to avoid confusion. This may underestimate species native to other parts of the country but introduced into the Pyrenees. However, it ensures the database is homogeneous and relevant for management. One exception was made for fish species native to continental Spain and/or France, but deliberately introduced into high-altitude Pyrenean lakes, where they are non-native and have strong ecological impacts.

- Taxonomic scope. All taxonomic groups were included except pathogens and microorganisms whose native range is often difficult to determine. The taxonomic level of the database is species. Subspecies were included at the species level only when the entire species can be considered non-native.

- Spatial information. We only included species with georeferenced records in the Pyrenees. Species without any information of presence were excluded.

- Naturalisation in the wild. We included species that are naturalised in the wild, excluding those clearly associated with cultivated fields and indoor environments with no evidence of escape potential (e.g. home pets, greenhouse species).

Given the difficulty of discerning established from casual records and their persistence over time, we followed the precautionary approach and kept all NNS meeting our inclusion criteria. This choice may overestimate the number and distribution of NNS but avoids underreporting.