Tweeters,

This is an abstract from the recent issue of Journal of Field
Ornithology. (Spring 1998, Vol 69, No. 2) I think it relates directly to
our discussion of the white windows in the wings of some Heerman's Gulls.
Spelling mistakes are my own.


Pied Plumage in Bald Eagles
(Pgs. 326-335)
Alan R. Harmata (Montana State University) and George J. Montopoli
(University of Wyoming)

Abstract- Nestling and adult Bald Eagles (Haliaeetus leucocephalus)
banded and observed in the Greater Yellowstone region of northwestern
Wyoming and southesastern Idaho displayed previously unrecorded plumage
and talon coloration. Atypical characteristics were noted in nine
nestlings and three adult Bald Eales associated with the Snake River
watershed between 1979 and 1989. Atypical plumage in nestlings was
characteristic of genetically based pied plumage (ie, feathers either
completely white or completly brown, not diluted, speckled or partially
albino). Pied plumage in nestlings was manifested as one or all of the
following abnormal characteristics: a wedge of white feathers on the
crown, white breast patch, white chin, abdomen, and crissum feathers,
white epaulets, and in one case, a completely white primary feather. One
parent of a brood of affected nestlings exhibited atypical
characteristics while parents of another brood were normal. Pied plumage
was expressed only in female Bald Eagles and was associated with white
(normally black) talons in both nestlings and adults and partially yellow
(normally all black) cere in nestlings. Pied plumage may be masked in a
definitive plumage of Bald Eatles or at least not obvious when viewed
from a distance. Pied plumage in nestling Bald Eagles may be unique to
Greater Yellowstone and proximity of affected eagles exhibiting pied
plumage indicated close genetic relationship among resident breeding
pairs.

Jim Rosso
Issaquah, Washington
jrosso at mediaseek.com
jlrosso at msn.com
(425) 392-8440