bird of passage
n.— «A convenient way was found to reconcile the contradiction, said Camille Guérin-Gonzales, a professor of history at the University of Wisconsin and the author of “Mexican Workers and American Dreams.” No quotas were necessary to keep Mexicans out because they were not going to stay. “Not wanting to ‘mongrelize the race,’ but needing cheap labor, Americans constructed Mexicans as ‘birds of passage’” she said, using the phrase coined to describe Italian immigrants. “The proximity of the border made that even more believable.”» —“100 Years in the Back Door, Out the Front” by Nina Bernstein New York Times May 21, 2006. (source: Double-Tongued Dictionary)