The Black Vulture above shows off the feathers that allow it to soar the skies. The feathers of the wings and tail are major reasons a bird can generate lift and thrust and also maneuver in shifting air currents. You can count the feathers- about 70- that make up the flight feathers.
And yet, according to Feathers by Thor Hanson, hummingbirds have around 1,000 feathers and swans have up to 25,000 (apparently mostly in the neck) (2011). Most birds have less than 10,000 feathers, with smaller birds having in the lower thousands (Wetmore 1936). Even if the Black Vulture above had only 1,000 feathers, its feathers primarily dedicated to flight represent less than 10% of the total. Although all feathers contribute to flight by streamlining the bird and reducing its weight relative to other substances, they do so much more.
|Down feathers on a baby Chipping Sparrow.|
|A feathered dinosaur on exhibit at the American Museum of Natural History.|
Although there is still much unknown, according to Hanson, it is generally
accepted by most scientists that birds evolved from theropod dinosaurs.
Additionally, fossil evidence points to feathers evolving earlier than
any known birds, which means that birds were not the only organisms
to have them (some non-avian theropod dinosaurs had them too).