with the exception, curiously enough, of the Rock Dove, the wild progenitor of 

 our domestic birds, which places its nest in inaccessible caverns in the face of 

 cliffs. The almost total extermination of the Passenger Pigeon has been in- 

 stanced as an example of a ''mistake" of Nature in allotting to it white eggs, 

 the absurdity of which statement is apparent when we consider that the havoc 

 was wrought upon the adult birds, and by man. 



Wallace has suggested that the nests of doves are so loosely and so flimsily 

 built — being in reality mere platforms of sticks — that, looking up at them, the 

 eggs simulated the color of the sky beyond and so became inconspicuous; but 

 unfortunately that argument is so decidedly suggestive of human presence that it 

 loses much of its value when we remember that egg-hunters among the mammals 

 and birds do not stand on the ground to take observations, but either climb the 

 trees in search of nests or fly low above the branches. 



The eggs of ducks and grouse are white or very light colored, and are laid in 

 open nests upon the ground. The mother duck's plumage is the very essence 

 of the mottled light and shadows among reeds, and when she leaves her eggs 

 she backs carefully away, drawing over them at the same time a coverlet of beau- 

 tiful down, the protective coloring of which is ample to shield the eggs. Ordi- 

 narily this coverlet is rolled up at the edge of the nest. It is to such a habit that 

 the eider-down hunters owe their supply. A grouse does not pluck the down from 

 her breast, but in devotion and ability to remain close upon the eggs she has few 

 equals. It is rare indeed to find the nest of a grouse unguarded, and the mother 

 bird will all but wait until your hand is upon her before leaving her eggs exposed. 



The many species of humming-birds lay the whitest of eggs, but here it is 

 the nest which is protected — fashioned of dull-hued plant down, with beams and 

 rafters of cobwebs, covered outside in our Eastern species with lichens exactly 

 like those which are growing upon the limb to which the tiny air-castle is attached. 

 The nests of vireos, also, are much like their surroundings. 



Many of the more isolated cases of exposed white eggs are to be explained, I 

 think, by the fact that the habits of birds often change rapidly, while their 

 structural adaptation follows more slowly. For example, let us take the group of 

 owls. The majority of these birds nest in hollow trees, but even these occasionally 

 make uss of an open hollow or a very shallow one, and individual, radical depar- 

 tures from the conventional owl habitation are doubtless not uncommon. But 

 these exposed eggs are soon destroyed; for no crow, jay or squirrel could ever 

 resist the opportunity to avenge himself for the wrongs inflicted by this ancestral 

 enemy, the owl. But when, urged on by that impulse which ever tends to make 

 birds vary their habits in all directions, some owl, such as the Short-eared, finds 

 good feeding on marshes and open, treeless plains, it naturally takes to nesting on 

 the ground in nests but partly concealed by the overhanging grasses. 



At one time the sandpipers and plovers were classed as wading birds, and 

 the gulls and terns in an order placed at a remote distance in the scheme of classi- 

 fication from the former birds ; no one suspecting that the two groups were in any 



671 



