70 
NORTHERN THREE-TOED WOODPECKER. 
for by difference of sex, age, or locality: thus, in some specimens 
the cervix is described white, or partly whitish, instead of being 
wholly black: the back is also said to be waved with white; 
which is indeed the case, and with the cervix also, but only in 
young birds. There is a circumstance however that could not 
be explained by supposing a difference of age, for while some 
specimens are seen with no appearance of white or yellow on the 
crown, but having that part as well as the body, rich shining 
black, others with a good deal of lemon yellow on that part, are 
of a duller black, much varied with white. As in other doubtful 
and intricate cases, these obscurities are dissipated by a close 
inspection and unprejudiced observation of nature, and we feel 
much gratification in being enabled to unveil to ornithologists the 
mystery of these diversities of plumage in this species, by merely 
pointing out the sexual differences, as well as those originating 
in the gradual change from youth to maturity in both sexes; 
which when understood, will not be found more extraordinary 
than in other species. 
The adult Female has never been recognised by any author, 
nor, hitherto, even by ourselves, having been misled by others in 
taking the young for her; and this we have only discovered by 
inspecting a great many specimens. She is precisely similar to 
the male, even in the minutest particulars, excepting the absence 
of yellow on the head, this part being of a rich and glossy black. 
The young of both sexes are of a dull blackish; the setaceous 
feathers of the nostrils are grayish, somewhat tinged with rusty; 
all* the feathers of the crown are tipped with white, constituting 
thick dots on that part, to which they give a silvery appearance; 
the cheek-bands are obscure and much narrower; the cervix is 
more or less varied with white, and the feathers of the back 
being banded with white, gives to that part a waved appearance; 
the under parts are more thickly waved with black: six, instead 
