May 21 2010
Two weeks ago my anatomy lessons embarked on the subject of birds’ feet but I’m changing gears today for a special edition. We need to know about pin-feathers right now.
If you’ve been watching the peregrine nestlings on the Cathedral of Learning webcam you’ve noticed that our former balls of fluff now look kind of spiky, have brown patches among the white, and are spending a lot of time grooming. That’s because their juvenile feathers are growing in.
New feathers are called pin-feathers because they’re covered in a sheath that makes them look pin-like.
When pin-feathers are quite small they have a blood vein inside that makes them sensitive to touch. As the feather grows the blood vein recedes, the feather barbs emerge from the sheath (indicated by the red arrow) and the feather is no longer senstive to touch. The sheaths dry out and fall off, a process the bird helps along by preening.
Molting makes birds feel a little itchy so they enjoy preening and bathing while they’re losing their old feathers and growing new ones.
So that’s why the nestlings are grooming a lot, removing the lose downy feathers and preening the new ones.
And that’s why they stand out in the rain. “Ahhhh! That feels good.”
Soon they’ll be covered in brown and cream feathers. You’ll be amazed at how fast this happens.
(photo by Jack Rowley at the Pitt peregrine banding in 2003)