Hundreds of monk parakeets, escapees from the pet trade, have settled beneath the city’s elevated highway. The non-native birds have become an unlikely fixture in the urban landscape of the Windy City, where large numbers of the striking green-and-gray parakeets live year-round. Chicago is on a main flyway for migratory birds, but monk parakeets have put down deep roots here. The South American members of the parrot family were brought north in the 1950s and 1960s and sold as pets, But they have long had fans in high places here. Former Chicago Mayor Harold Washington, who lived across the street...