BIRDS' NESTS AND EGGS 369 



Again, the young birds of many species absolutely depend 

 for safety on the colour of their down. The Lapwing is 

 arrayed in tints that put us in mind of the tropics ; the sexes 

 are alike ; yet they build an open nest on the bleak common, 

 moor, or pasture, where sometimes not a shrub or heath tuft 

 affords a haven of safety. Both birds lack weapons of defence ; 

 but note how the safety of their young is ensured : their 

 sombre downy plumage effectually conceals them from view. 

 Upon the least alarm the brightly-coloured parents leave their 

 helpless young, who instantly crouch to the ground and 

 remain motionless ; their colour so closely harmonises with 

 surrounding tints as to hide them effectually from enemies. 

 The young of the Game Birds, of all the Sandpipers, and the 

 Plovers, and of many sea-birds, might also be given as instances, 

 all of which (where the parents' plumage is conspicuous and 

 dangerous to the welfare of their eggs and young, and which 

 nest in an open site) have young of protective tints. 



As we found the anomaly of white eggs in open nests, so 

 we also find that of spotted and highly-coloured eggs in 

 covered nests. We take as our first example the Jackdaw, 

 whose eggs are spotted and coloured in a remarkable manner, 

 considering they are laid in a covered nest. The Chough is 

 another instance, and the Magpie a third. I am inclined to 

 believe that these three birds have changed the position or 

 the form of their nest from an open to a covered one, and the 

 eggs are consequently gradually losing their markings. The 

 eggs of these birds are generally much paler than the eggs of the 

 Crows laying in open nests, and they seem slowly reverting to 

 a colourless type. When once any particular development 

 ceases to be of service, its tendency is gradually to die out ; 

 and this, I think, is the reason that so many birds nesting in 

 covered sites lay eggs only slightly spotted ; or, as in many 

 cases, when compared with the eggs of the family of birds to 

 which they belong, show a marked decrease of coloration.. 



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