Japan Reveals Hummingbird Wing Secret

Footage shot with high-speed cameras has revealed how hummingbirds' tiny wings bend and flex to keep them in the air. Masateru Maeda, a PhD student at Chiba University in Japan, captured the footage as part of a study that eventually aims to build hummingbird-inspired artificial wings. The researchers found that the birds' primary feathers - the main flight feathers along the outer edges of their wings - slide as they flap. This changes the shape and size of the wing, precisely controlling the lift that the wings produce.

The research was presented at the Society for Experimental Biology's annual meeting in Valencia, Spain. Hummingbird Hummingbirds are birds that comprise the family Trochilidae. They are among the smallest of birds, most species measuring in the 7.5–13 cm (3–5 in) range. Indeed, the smallest extant bird species is a hummingbird, the 5-cm Bee Hummingbird. They hover in mid-air by rapidly flapping their wings 12–80 times per second (depending on the species ).

They are known as hummingbirds because of the humming sound created by their beating wings, which sometimes sounds like bees or other insects. To conserve energy while they sleep or when food is scarce, they have the ability to go into a hibernation-like state (torpor) where their metabolic rate is slowed to 1/15th of its normal rate. When the nights get colder, their body temperature can drop significantly and thus slow down their heart and breathing rate, thus burning much less energy overnight. As the day heats back up, the hummingbirds' body temperature will come back up and they resume their normal activity.

They can fly at speeds exceeding 15 m/s (54 km/h; 34 mph ); they are also the only group of birds with the ability to fly backwards. Individuals from some species of hummingbirds weigh less than a penny. Aerodynamics Of Flight Hummingbird flight has been studied intensively from an aerodynamic perspective using wind tunnels and high-speed video cameras. Writing in Nature, the biomechanist Douglas Warrick and coworkers studied the Rufous Hummingbird, Selasphorus rufus, in a wind tunnel using particle image velocimetry techniques and investigated the lift generated on the bird's upstroke and downstroke.

They concluded that their subjects produced 75% of their weight support during the downstroke and 25% during the upstroke. Many earlier studies had assumed (implicitly or explicitly) that lift was generated equally during the two phases of the wingbeat cycle, as is the case of insects of a similar size. This finding shows that hummingbirds' hovering is similar to, but distinct from, that of hovering insects such as the hawk moths.

The Giant Hummingbird's wings beat is as low as 12 beats per second, the wings of medium-sized hummingbirds beat about 20 to 30 beats per second and the smallest can reach 100 beats per second during courtship displays. A slow-motion video has shown how the hummingbirds deal with water when they are flying. To remove the water from their heads, they shake their heads and body, similar to a dog shaking to shed water.

Wing Structure and Colors Many of the hummingbird species have bright plumage with exotic coloration. In many species, the coloring does not come from pigmentation in the feather structure, but instead from prism-like cells within the top layers of the feathers. When light hits these cells, it is split into wavelengths that reflect to the observer in varying degrees of intensity. The Hummingbird feather structure acts as a diffraction grating. The result is that, merely by shifting position, a muted-looking bird will suddenly become fiery red or vivid green.

However, not all hummingbird colors are due to the prism feather structure. The rusty browns of Allen's and Rufous Hummingbirds come from pigmentation. Iridescent hummingbird colors actually result from a combination of refraction and pigmentation, since the diffraction structures themselves are made of melanin, a pigment.