European Starlings look like (actually 940, with a few Brown-headed Cowbirds mixed in). Between 1890 and 1891 the American Acclimatization Society released 160 of these non-native birds into Central Park. It is unclear how many of these releases failed, but the first breeding pair was eventually found nesting under the eaves of the American Museum of Natural History. Love them or hate them, they appear to be here to stay. Check out this interesting piece by May Thacher Cooke from 1928 on starling's spread through North America.