Having the largest wing-area-to-body-weight ratio of any bird, frigate birds are essentially aerial. This allows them to soar continuously and only rarely flap their wings. One great frigate bird, being tracked by satellite in the Indian Ocean, stayed aloft for two months. They can fly higher than 4,000 meters in freezing conditions. Like swifts they are able to spend the night on the wing, but they will also return to an island to roost on trees or cliffs. Field observations in the Mozambique Channel found that great frigate birds could remain on the wing for up to 12 days while foraging. Highly adept, they use their forked tails for steering during flight and make strong deep wing-beats, though not suited to flying by sustained flapping.
Frigate birds bathe and clean themselves in flight by flying low and splashing at the water surface before preening and scratching afterwards. Conversely, frigate birds do not swim, and with their short legs cannot walk well, and they do not take off from the sea easily. The average life span is unknown but in common with seabirds such as the wandering albatross and Leach’s storm petrel, frigate birds are long-lived. In 2002, 35 ringed great frigate birds were recovered on Tern Island in the Hawaiian Islands.
Of these ten were older than 37 years and one was at least 44 years of age.
Despite having dark plumage in a tropical climate, frigate birds have found ways not to overheat—particularly as they are exposed to full sunlight when on the nest. They ruffle feathers to lift them away from the skin and improve air circulation, and can extend and upturn their wings to expose the hot undersurface to the air and lose heat by evaporation and convection. Frigate birds also place their heads in the shade of their wings, and males frequently flutter their gular pouches.
In a spectacular courtship display, male Magnificent Frigate birds sit in varying size groups, throat sacs inflated, clattering their bills, waving their heads back and forth, quivering their wings, and calling to females flying overhead. Frigate birds are skillful hunters. They snatch food from the surface of water while flying past, and chase other birds to force them to disgorge food, which is caught in flight before it hits the water.