The frigate bird is a powerful and aggressive seabird, with a deserved reputation as the pirate of the high seas. One of world’s fastest birds, he swoops and soars up to 100 miles an hour, spending up to 12 days at a time on the wing, even sleeping in the air. He ekes out a tenuous existence from the resource-poor surface of the tropical ocean, in a environment with little nesting land. To achieve this, the frigate has jettisoned anything not essential to life in the air. His tiny feet and legs do not allow him to sit or walk, and its seven-foot wingspan skeleton weighs only 4 ounces: less than his feathers. What can this exquisitely evolved aerial acrobat teach us about flight? Find out in today’s entry of The Biomimicry Manual.
Remarkably light for his size, the frigate has the highest ratio of wing area to weight, and the lowest wing loading of any bird. His bones are hollow, and fully half of his total weight is feathers and flight muscles. Like tissue paper attached to a huge sail, he spreads his wings and effortlessly floats on tropical marine thermals. His flight skills are enviable by any NASA or Air Force standards. He is by far the biggest bird that can hover in one spot, and his bowed wings give him exceptional twisting and turning capabilities. His rudder-like forked tail, one of the longest functioning tails among birds, lets him to turn on a dime, while his fused pectoral girdle, the only one in the bird world, stabilizes his high-speed twists.
Strangely, for a seabird, frigates are not waterproof. They have abandoned oil-producing glands, and if they land in the sea or get wet, they cannot take off and will drown. Unlike pelicans and cormorants, to which they are related, they can’t plunge into the water after prey, nor even float on the water. Instead, they catch flying fish on the wing, following schools of tuna or pods of dolphins as they drive schooling fish to the surface.
They have another trick for getting a free lunch. They bully and harass other birds, pulling on their tail feathers, biting their legs, and dragging them by their wings. They will go so far as to stick their bills down another bird’s gullet to steal their fish. Birds that resist suffer broken wings, exhaustion, and death. Often the victim will regurgitate food to ditch its tormentor. The bully dives to catch it before it hits the water.
Could NASA or the Air Force learn something about flight from this exquisite aerial predator? There could be no finer teacher than these tenuous pirates. He is the master of hovering, twisting, turning, and high-efficiency soaring, while focusing on his victims. A pirate’s life for me!
An evolutionary biologist, writer, sustainability expert, and passionate biomimicry professional in the Biomimicry 3.8 BPro certification program, Dr. Tamsin Woolley-Barker blogs at BioInspired Ink and serves as Content Developer for the California Association of Museums‘ Green Museums Initiative. She is working on a book about organizational transformation inspired by nature.
All images via Wiki Commons