Dennis,

I like your idea. I should emphasize that I never thought that feathers
lost and replaced outside of normal molt periods grow back white as a
general rule! There is certainly evidence that that is not the case, as
you mentioned. My thought was that sometimes white feathers grow in at
the site of an injury. The poster who mentioned older female ducks with
white feathers on the nape presented some support for that idea, in that
during multiple matings over a few years, female ducks are likely
occasionally to lose more than just a couple feathers. Male ducks can be
pretty rough during mating. The specific example I originally mentioned,
involving male passerine head injuries resulting in white replacement
feathers, also could involve more than just feather loss. I was thinking
at the time of a male song sparrow at Discovery Park who is recognizable
by some white head feathers - I forget if the observer mentioned a
previous injury or if I just made that up. Anyway, I can't very well
advocate intentional mutilation of captured birds ;) so the feather
plucking experiment seems a harmless experiment that might turn up
something.

Stranger things do happen than replacement feathers growing in white on
the site of an injury - consider the white-tailed deer: an injury in
the right side of the body (leg, for example) often results in the deer
growing a deformed *left* horn in subsequent years.

On Mon, 20 Mar 1995, Dennis Paulson wrote:

> Well, an experimental technique has made itself clear. Bird banders, if
> you are catching birds that are resident in your yard (i.e., you see them
> regularly), why don't you pluck a single feather from each of several
> places on the bird and see if they grow in white? On a moderately dark
> bird, this should be quite obvious. Enough of such experiments would
> answer a lot of the questions posed here. I'm entirely serious, although I
> hope I'm not being politically (or environmentally) incorrect.
>