First record of a possibly overlooked impact by alien parrots on a bat (Nyctalus leisleri)

Although its interferences on native biodiversity are still poorly known, the rose-ringed parakeet Psittacula krameri is currently recorded as one of the 100 worst alien species. The impacts on native fauna by this parrot are mainly represented by the displacement of native birds from nesting sites, with direct lethal attacks observed only against little owls and red squirrels. To date, competition with bats for tree cavities has been hypothesized but not documented yet. We recorded a fatal attack of a parakeet towards a Leisler’s bat (Nyctalus leisleri), roosting or possibly hibernating in a trunk cavity. Although this is the only report available, the fact that both parrots and many bat species use tree cavities suggests that similar cases may be relatively frequent although sporadically observed. This observation puts emphasis on the need to supporting active monitoring and management of introduced species populations to preserve threatened native fauna.