Because authorities have found a live alligator swimming in the Chicago river. He's a little guy only about 2-3 feet long but he can no doubt feast on all those Asian carp we keep hearing about in Chicago.
Nice video: http://www.bbc.co.uk/news/world-us-canada-11089018
Nice video: http://www.bbc.co.uk/news/world-us-canada-11089018
Comment