USDA National Wildlife Research Center Symposia


Date of this Version

August 2007


Published in: Witmer, G. W., W. C. Pitt, and K. A. Fagerstone, editors. 2007. Managing vertebrate invasive species: proceedings of an international symposium. USDA/APHIS Wildlife Services, National Wildlife Research Center, Fort Collins, Colorado, USA. Also available online at


Parrots have been transported around the world since the 1400s and about 44 species have established populations outside of their native ranges. At least 70% of these introduced species were identified as potential agricultural pests, compared to only 15% of all parrot species. At least 74 exotic psittacines have been reported in the wild in the United States, but only nine species were considered established. Since 1990, 24 psittacine species have been sighted in the wild in Hawai`i, about 21 species regularly occur on the main islands and at least five appear established. Past history of successful introduction, recent status of introduced populations, and life history traits were used to identify parrots which, if introduced, appeared most likely to establish nonindigenous populations. Potential impacts related to ecology, agriculture, and health were diverse but poorly documented in the literature. Five species were the most widespread and abundant species, and were considered established. Four more species with rapidly expanding ranges and increasing populations may become naturalized. Nine species had significantly expanded ranges and increased populations. Several introduced populations remained low for 10-15 years before rapidly increasing and becoming established; similar lag periods for other psittacines have approached 30 years.