Frigatebirds have to find ways to stay aloft because they can't land on the water. Since their feathers aren't waterproof, the birds would drown in short order. They feed by harassing other birds in flight until they regurgitate whatever fish they've eaten and the frigatebird takes it. Or they fly over a fish-feeding frenzy on the ocean surface and scoop up small fish that leap out of the water to escape larger fish.
So in between meals, apparently, frigatebirds soar ... and soar ... and soar.
In one case, for two months — continuously aloft.