While we may think that the ability to fly makes birds unique among all animals, but there are bats that also fly. So while flight is remarkable and birds have perfected it, it is really feathers that set birds aside from all other animals. There are a lot of different anatomical features that aid flight, but the most important are the feathers! I am thinking about them today because sadly we had an Ovenbird fly into a window and die. As I carried it into the forest to its final resting place I marveled at the perfection of its newly molted feathers – so fresh and silky smooth, with perfect edges – not ragged and worn as they would have been a month ago.
I have also been fortunate to be able to band birds, which means I’ve held hundreds in my hands over the years and I have been able to observe all the final and beautiful details of their feathers – a rare gift.
Every inch of a bird’s body are covered by feathers, except for their beak, part of their legs and feet, and for some (vultures) their heads. (Some owls do have feathers covering their legs and feet.) The size of the bird ultimately determines how many feathers cover the body. There is somewhere around 1000 on a Ruby-throated Hummingbird and 25,000 on a Tundra Swan.
Feathers are made of keratin, a strong protein that is also in our hair and fingernails. While they are growing feathers are being supplied with blood through the hollow shaft (calamus). If a bird breaks a feather at this time, it will bleed. Eventually the feather is fully grown, the blood supply stops and the feather is then inert.
Not all feathers on a bird’s body are the same, because they perform different functions. Those right next to the body are down and semi-plumes, there are contour feathers on the head and breast, primary and secondary feathers on
the wings known as flight feathers and tail feathers (rectrices) that help the bird maneuver through the air. Flight, contour and semiplumes all have a central rachis, which we call the quill. From this come over 1000 small structures known as barbs. This where you often find the most color. Coming off the barbs are more than 1000 barbules that lock the barbs together. Finally at the end of the barbules are barbicels which keep everything interlocked or ‘zipped’ together, thereby creating a ‘vane’.
If you find a feather on the ground, hold it up and run your fingers down from the top. This will cause the feather to ‘unzip’ or look rough and in disarray. Then run your fingers back up the feather to the top, causing the barbicels to reconnect and bring the feather back to its original shape. This is one of the things birds are doing when you see them preening their feathers. They are using their beaks to make sure all their feathers are in perfect condition for flight.
Non-migratory birds only molt (replace old feathers with new ones) once a year, after the breeding season has
passed. Migratory species go through two complete feather molts; once before breeding season and again afterwards. All feathers suffer wear and tear through the activities of everyday life and molting takes tremendous energy from the bird’s body to accomplish. When chickens molt (once a year) they stop producing eggs. Since keratin is 90% protein, it important to offer high-protein bird food at the end of the nesting season when the migratory birds are preparing for their southern journey. Good choices include nyjer seed and raw peanuts.
By Kate Crowley