Worldwide impact of alien parrots (Aves Psittaciformes) on native biodiversity and environment: a review

More than 16% of parrot species (Aves Psittaciformes) of the world have currently established at least one breeding population outside their natural distribution ranges. Though including the most introduced bird species all over the world, their interactions with native biodiversity and environments are still poorly known. In this paper, we summarize current knowledge about impacts of introduced Psittaciformes and we identify possible gaps to be filled with future research. Breeding site requirements of alien parrots, e.g. trunk cavities, indicate potential routes of direct and indirect competition with native hole-nesting bird species. Interactions with arboreal rodents, bats and insects are poorly documented, but appear to be limited. Psittaciformes potentially affect economy and human wellness, being responsible for damage to crops and to electrical infrastructures. Association with noise pollution has also been suggested, as many alien populations breed in urban parks or close to human settlements. Psittaciformes are potential reservoirs of Chlamydophila psittaci, the etiological agent of human psittacosis, and other diseases transmittable to humans and wildlife. Less is known about impact on native flora as well as on ecosystem functions. Predictive research and information on ecosystem recovery after parrot removal are scarce too, as eradication programs are often hampered by the emotional affiliation linked to these birds.