Modelling the potential spread of the Red-billed Leiothrix Leiothrix lutea in Italy

Capsule: The introduced Red-billed Leiothrix Leiothrix lutea can greatly expand its range in Italy, with many regions being at high risk of invasion due to their high habitat suitability.

Aims: To assess the environmental variables affecting the distribution of the Red-billed Leiothrix during the invasion process, and to predict the potential distribution of the species in Italy.

Methods: We retrieved data on 548 occurrences from Liguria (northern Italy), Tuscany, and Latium (Central Italy) using the Ornitho.it portal, a citizen science-based resource. We used species distribution models to assess the most important climatic and landscape variables for the presence of the species and to generate a countrywide habitat suitability map.

Results: Red-billed Leiothrix distribution was jointly affected by climatic and landscape variables, being related to precipitation seasonality, percentage cover of agricultural areas, and annual precipitation. Habitat suitability for the species was highest at intermediate levels of precipitation seasonality, decreased with the amount of agricultural areas, and increased with annual precipitation. The results of species distribution models were highly consistent across regions. The areas with the highest suitability for the species occurred in a strip spanning the northern and western sides of Italy, particularly in regions with a Mediterranean climate.

Conclusion: Broad areas of Italy have a high risk of invasion by the Red-billed Leiothrix. We provide fine-grained information on the magnitude of habitat suitability over the Italian peninsula.