BROOD-CARE IN BIRDS 155 



birds almost every kind of egg, white, evenly tinted with some 

 bright colour, spotted or blotched, is to be found, and he would be 

 ingenious indeed who could arrange them in a system coherent 

 with their environment. 



The explanation of the whiteness of white eggs as an adaptation 

 to the kind of places in which such eggs are laid requires a great deal 

 of bolstering up and stretching to make it fit the facts. So also the 

 theories of similar adaptations in the case of coloured eggs require 

 still more special pleading. Certainly many of the blotched eggs 

 which are laid on rocky ground or left uncovered amidst low herbage 

 fit their surroundings extremely well, and may be protected by 

 their invisibility. But there are other spotted and blotched 

 eggs which are laid in holes or on inaccessible ledges, or in covered 

 nests, and the explanation of protective resemblance is far from 

 complete. It seems almost impossible to imagine that there is 

 any protective advantage in the brilliantly coloured eggs, those 

 with purple or green or light blue or burnished red hues, and to 

 add to the difficulty these are laid in all sorts of situations, on the 

 ground, in holes, or in covered or uncovered nests. The ingenious 

 suggestion has been made that the original egg-eaters from snakes 

 to monkeys became accustomed first to white eggs, as primitive 

 eggs were all white, and that later on the bright colours puzzled 

 them, and made them fail to recognise that such gaudy objects were 

 edible. Hungry animals, however, are so experimental, so disposed 

 to try the taste of every strange object that comes before them, that 

 I do not think this suggestion carries us very far. If it were the 

 case that brightly coloured eggs were often addled, or had nasty 

 tastes, as happens with many brightly coloured insects, one might 

 believe that egg-eaters after a few experiments would give them up. 

 But as any daring animal that refused to be put off by colour, or 

 any animal with no natural appreciation of colour, would at once 

 discover that the colour was only shell-deep and that the contents 

 were excellent, protection would soon come to an end. 



We have to remember, however, that the existing colours and 

 patterns of eggs and of animals may be survivals from circumstances 

 in which they were useful. Animals, even in recent times, have 

 spread from one country to another, have been driven or have 

 migrated from the hills to the plains, from the jungle and forest to 

 barren, open country. They have changed their habits from choice 

 or from necessity. Birds of the same species often nest under 

 different circumstances in very different places, sometimes in holes. 



