Two large feathers fell to the ground in Carson’s mew this week, marking the beginning of her annual molt. Over the next few weeks she will drop all of her feathers to grow a new set. This most recent molted pair of feathers mirrored each other: one curved to the right, one curved to the left. The shape tells me the feathers came from her wings: one from the right wing, one from the left wing.
The asymmetrical shape is most pronounced in the primary flight feathers, those farthest out on the wing where her fingers would be. If we take a look at “P10,” the outermost primary feather, we can clearly see the center shaft running closer to one edge of the feather vane:
As the bird flies, this is the first feather to cut through the air and the narrower vane (the top side in this photo) will be the leading edge. (So we know this feather came from the right wing.) The asymmetrical shaft assists with aerodynamics and feather stability in flight. One of the next primaries has a slightly different shape:
The shaft is still asymmetrically placed, but both leading and trailing edges have notches that make the tip of the feather more narrow. When the wing is spread, these outer feather tips separate like individual fingers to reduce drag. It seems amazing that these feathers are so well designed to optimize efficiency in flight.
Find out more about identifying feathers at The Feather Atlas website.