INTRODUCTION. xi 
in colour, and that of the female dull and sombre, and which nidifi- 
cate in open sites.—The merest tyro in ornithology is aware that the 
plumage of the female bird is in a great many cases far more sombre than 
that of the male. Until comparatively recently the cause of this pheno- 
menon was never dreamed of. It is an ascertained fact that the colour of 
many female birds is connected in no small degree with their mode of 
nidification, and that the sitting bird is protected by the harmony which 
exists between its own sober plumage and the colour of the surroundings 
of its nesting-site. Let us glance over the nesting-habits of some of our 
best-known birds, and learn the working of this law. The males of many 
of our common birds possess extreme brilliancy of plumage, whilst their 
females are of such dull and inconspicuous colours that an inexperienced 
person would suppose them to belong to different species. The gorgeous 
Pheasant (Phasianus colchicus), for instance, has a mate whose garb is dingy 
and subdued in the extreme. Her sober plumage, however, is of the greatest 
importance ; for on this cirenmstance in part depends the very existence of 
her species. She builds her slight nest on the ground, and her plumage 
harmonizes with the dead bracken and dry herbage around, and most 
effectually conceals her from her enemies. A still more striking instance 
is to be found in the Black Grouse (Tetrao tetrix). The male bird is 
dressed in a rich garb of purplish black, but his mate does not resemble 
him in the least degree ; indeed, so widely does she differ in the colour of 
her plumage as to defy even the most expert ornithologist unacquainted 
with the matter, so far as outward appearances go, to class her as the same 
species as her mate, her plumage being mottled brown of various shades. 
But this diversity of plumage between the sexes serves the great purpose 
of shielding the female during the season of nidification on the brown 
heathery wastes where she rears her young. Take another instance. The 
Mallard, or Wild Duck (Anas boschas), exhibits such brilliant tints as to 
render him one of the showiest of our native birds; but his mate is of dull 
and inconspicuous colours, which harmonize closely with the tints of her 
nesting-site, which is an open and exposed one. Again, the male Teal 
(Anas crecca) is richly adorned, but his mate is so dull in plumage as to 
suggest the idea of their being distinct species. By this great differ- 
ence in the sexes the same end is served; for the female Teal builds 
an open nest, and the safety of that nest and its eggs depends on her dull 
and sober plumage. Amongst our smaller birds we have many instances : 
the Blackbird (Merula merula) mated to a dull brown spouse, who sits in 
an open nest, and the Ring-Ouzel (M. torquata) may be cited. The male of 
the latter species is showy, rich black and grey, with a snow-white band 
across the breast; the female is brown, and the band across the breast is 
dull—a plumage in harmony with the brown tints of the moorland, where 
she sits upon her open nest comparatively safe. The male Chaffinch 
62 
