Definitely contact the Conservation Department BEFORE you start shooting. The red tailed hawk is legally protected in Canada, Mexico and the U.S. by the Migratory Bird Treaty Act of 1918. You can almost always get approval to shoot whenever your animals are threatened, but they like you to ask first.
They may even come help. We have lots of hawks, coyotes, and eagles. Has anyone had problems with eagles and Yorkies?
Watch those babies.