Some(a few thousand) of the flock has made to SW Arlington (my neck of the woods) and they darken the shopping strip in the evenings. They are fascinating to watch and listen to—from a distance. But they do leave a nasty, potentially dangerous mess, and as you mentioned, drive away more desirable birds.
They should be rounded up and deported back yonder to Mexico, whence they came.
Bird seed salted with lead shot.
Some people complained.
We can't even deport the vast majority of illegal Mexicans in our country; deporting their wretched birds would be even harder. We're just going to have to shoot them - the birds, of course.