What kind of bird is this?

The magnificent frigatebird spends most of its life in the air. The magnificent frigatebird hunts mainly flying fish. It lives in the open waters, islands and coasts of the Western Atlantic Ocean (from Florida and the Caribbean to southern Brazil) and the Eastern Pacific. It owes its name to a puffing throat sac, which when filled with air resembles a frigate sail stretched in the wind. It is found in the flag of Kiribati.