Reintroductions offer a powerful tool to reverse adverse anthropogenic impacts on biodiversity by restoring extirpated populations within the indigenous range of species. Reintroductions have become popular and have been increasingly used over the last decades. However, this species-centered conservation approach has been criticized for being taxonomically biased and for focusing on large and charismatic species. Studies investigating taxonomic biases in the allocation of reintroduction efforts at a large scale generally consider taxonomic bias within and among higher taxa (e.g. vertebrates, plants), by comparing the number of reintroduced species within a taxon to its prevalence in nature. Here, we show that the bias is even more striking when accounting for the differences in the number of implemented programs among reintroduced species. We conducted a comprehensive search of the peer-reviewed and grey literature to inventory reintroduction programs of European terrestrial mammals. We identified 28 species that have been reintroduced at least one time. For each reintroduced mammal, we extensively searched two literature search engines and found 414 relevant publications, which described 375 distinguishable reintroduction programs implemented in Europe from the early 20th century to 2013. We used the number of implemented programs and the number of associated publications to investigate the distribution of reintroduction efforts among species. Our results show substantial heterogeneity in the allocation of reintroduction efforts, with 68% of implemented reintroductions in Europe involving only three species: the beaver (Castor fiber), the Alpine ibex (Capra ibex), and the European bison (Bison bonasus).
