A Continental-scale modelling approach for the Eurasian beaver expansion: biogeographic perspectives and management issues

The Eurasian beaver (Castor fiber), is a keystone species and an ecosystem engineer at landscape scale, which was close to extinction until the 19th century. Legal protection and reintroduction programs let the species recover and recolonize much of its past range, except for some countries.

We model its potential distribution for both current and futures scenario at European scale. We produce fine-tuned species distribution models at rivers and sub-basins level, using climate change scenarios, and predicted changes in river flow, also including topographic, habitat-related, and human disturbance variables. We further assess habitat suitability within Italian and Portuguese protected areas, in order to support possible reintroductions in these countries, once inhabited by the species.

We find that the Eurasian beaver’s current suitability is comparable to its known distribution. Although, we note that some potentially suitable patches occur in Italy (where the Eurasian beaver occurs in two areas), while the Iberian Peninsula and the Balkan countries host scattered suitable spots. Future scenarios show a general decrease in environmental suitability in large areas of central and northern Europe due to projected changes in climate and river flows, with the 2070 scenario worse than 2050. While Portuguese protected areas generally host territories with low suitability, the Italian protected areas have various levels of suitability based on the biogeographical sector considered.

Our results may support the large-scale management of the beaver, providing insight into the areas where the beaver may further expand in the future, both for countries already hosting this species and those interested in reintroductions programs. Moreover, the framework utilized may be useful for studies on other species, and for different research areas, from biogeography to conservation.