Anatomy: Pin-Feathers

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)

8 thoughts on “Anatomy: Pin-Feathers

  1. Thanks for the update on the feathers. Now I will await your update on the feet. They seem to be too big for the little ones and I noticed that they spend a lot of time looking at them–maybe like a baby who just discovers his feet (^+^). I will miss them when we can no longer monitor them.

  2. Great description and photo. I was having trouble picturing what the sheathed feather looked like, but the arrow on the photo made it clear. Thanks again, Kate.

  3. Lucie, an old name for peregrines was “Big footed Falcon.” They all have big feet. 😉

  4. They certainly do change quickly. Last Friday there was just a dark line along the edge of the tail and the wings where the juvenile feathers were coming in. Monday the thin line was replaced by a very wide line and you could see the individual feathers.

  5. Hi Kate: Thanks for all you do. Question: Do you still think the COL chick will fledge the Memorial Day weekend? They are not even ledge walking yet… Just wondering if I should plan on being out to watch that weekend.

  6. I think they are more likely to fledge the first few days of June but they will be ledge-walking and (hopefully) visible on the building on May 28. Also, if we catch it at the right time (always tricky) the parents will be giving flying demonstrations and bringing food.

  7. I plan to be there Sat. 5/29 bright & early. See you unless something untoward happens. Love that tulip tree.

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