They are almost, but not quite, like Canadian Geese which populate many green areas in the Philadelphia suburbs. I love them, but many hate them.
A few years ago I saw the police in New Jersey try to get rid of them on their station grounds with a leaf blower. They were defiant and the police were unsuccessful. Later that day I wrote an email to them (Woodbury, NJ) stating that there really were some (Canadian) illegal aliens who could successfully defy their directives to leave the country without having either a Visa or a Green Card. - David Lyga