The White-winged and Yellow-chevroned parakeets, natives of South America, were formerly considered subspecies of the Canary-winged Parakeet (see Systematics). Their popularity as pets led to their importation and the subsequent establishment of feral populations in California and Florida. More than 230,000 White-winged Parakeets were imported from 1968 to 1972, and large numbers of these birds apparently escaped, leading to the rapid appearance of this species in the metropolitan areas of Miami, Los Angeles, and San Francisco. In the early 1970s the Miami population of White-winged Parakeets was estimated at 2,000, and the birds occurred on both coasts of Florida. However, after 1972, the importation of White-winged Parakeets dropped to near zero.
Population dynamics of this species is difficult to interpret because of the irregular coverage of exotics on Christmas Bird Counts and the tendency of U.S. observers to report both White-winged and Yellow-chevroned parakeets as the “Canary-winged Parakeet.” But the White-winged Parakeet appears to have declined slowly since the early 1970s and contracted its range as imports stopped providing a source of fresh escapees. Today, it is unclear how many individuals remain in California, and in Miami, it appears their population numbers have dropped by approximately 99% in the past 5 years ( Aagaard and Lockwood 2016 ).
In the United States, White-winged Parakeets feed on a variety of fruits, seeds, buds, and flowers, relying heavily on exotic plantings of figs and other tropical species. When nesting in the U.S., the species excavates nest cavities in palm trees, whereas in their native range, nests are built in tree cavities and the arboreal nests of termites (Isoptera).
The White-winged Parakeet is a social species that feeds, roosts, and travels in groups, while pairs remain together almost continuously. At one time, roosting assemblages in Miami contained 700 or more individuals, and in South America groups of more than 1,000 have been reported. Despite their social nature, these parakeets are extremely aggressive. Studies of these parakeets have documented a well-developed array of threat displays, and suggest that even duetting by pairs is a way to improve success in agonistic interactions.
Historically, most information about this species in its native range has come from travelers’ anecdotal observations and what little is known about this species comes from general reviews of exotic species, anecdotal accounts, personal observations, and data gathered for this account. Over the past 15 years, very little research has been conducted on this species, especially in North America, with most of what is known about their basic biology is based on research from the 1970s ( Schroads 1974 ) and early 1980s ( Arrowood 1981 ). Most of the new knowledge about their basic is being generated by a handful of studies in their native range, with most research conducted on North American populations largely limited to analyzing population trend data, as opposed to field observations. Because of this, there is little known about their basic biology, including habitat preferences, detailed diet information, and nesting information. Moreover, it remains unknown if White-winged Parakeets impact native avifauna. Though, if their population continues to decline as it has, any future studies on this species in North America may only serve to help understand local extinction processes.