The ecological impacts of introduced parrots

Introduced and invasive species are negatively influencing native species at an alarming and increasing rate. Invasive species may alter the structure and the function of ecosystems by ways of hybridization, competition, predation, parasitism and disease. Over 60 parrot species have established at least one breeding population outside their natural extent of occurrence, thus being the most introduced bird species throughout the world. Impacts by introduced parrots are mostly known for the two most widespread species, the rose-ringed parakeet (Psittacula krameri) and monk parakeet (Myiopsitta monachus). Impacts may change across different study sites and population densities. Hybridization occurs only in tropical areas, where similar species are naturally present, as well as in introduction areas between two introduced species. Behavioural interference has been reported with a number of native species (birds, mammals and insects) sharing the same breeding or feeding areas of introduced parrots. Other kinds of impacts by introduced parakeets include economic effects (e.g. agriculture and electrical infrastructures) and human well being. In this chapter, we summarize the ecological impacts of introduced parrots, updating and improving the review by Menchetti and Mori (2014), attempting to draw conclusions from a worldwide perspective.