In the United States military, a full-bird colonel is in charge of brigades. A full-bird colonel is one rank below a one-star general, or brigadier general, and one rank above a lieutenant colonel. Someone can achieve this rank as early as their mid-40s.
The full-bird colonel holds the pay grade of O-6; in the U.S. Air Force, they are the 22nd rank. They are typically responsible for 1,000 to 3,000 airmen that are of a lower rank than them. Once someone reaches full-bird colonel status, they receive a silver eagle insignia that they are to wear on their left side.